Sunday, November 6, 2016

Neighborhood Mushroom Watch (Someone’s Got To Do It): Part III – Spore Release and Dispersal

“For the rain had ceased at last, and a sickly autumn sun shone upon a land,
which was soaked and sodden with water. Wet and rotten leaves 
reeked and festered under the foul haze which rose from the woods. 
The fields were spotted with monstrous fungi of a size and color
never matched before - scarlet and mauve and liver and black. 
It was as though the sick earth had burst into foul pustules; 
mildew and lichen mottled the walls, and with that filthy crop 
Death sprang also from the water-soaked earth.”

From Sir Nigel by Sir Arthur Conon Doyle, creator of Sherlock Holmes

The summer of 2016 in southern New England was mired in the most severe drought in nearly a decade. While everyone reveled in the near "perfect" weather, wells began to dry up, lakes became historically low and waterways withered into ponds and long stretches of exposed beds. Watering restrictions and bans were issued as some towns purchased water from the state's back-up reservoirs. Farmers lost millions in production, and officials declared many regions a natural disaster area.

Welcomed rains triumphantly arrived in late August, but it was too little, too late for stunted crops - but not so for fungi. As if waiting for the appropriate conditions, they responded with astounding speed to the call of wet weather by fruiting on forest floors, suburban lawns, tree bark, rotting stumps, decomposing leaves, wood mulch, compost and manure. The myco-celebration was brief, but it generated and released countless gazillions of spores throughout the night and before dawn. It's fungi's sole mission - species perpetuation assisted by gravity, wind, water, insects, mammals and ejection ballisitics.

With a Foul Stench, the Erotic and Vile, Rude and Provocative,
Shameless Mutinus Elegans Demands Your Fervant Attention

This is my third post on the fungi of New England in which I investigate various modes and mechanisms of spore release and dispersal. Part I (here) discusses fungal basics and their otherworldly lifestyles, while on a quest to study local members of Kingdom Fungi. Part II (here) is a "Summer Sampler" of some remarkable specimens that fruited overnight in my neighborhood.

Emerging mysteriously overnight after three days of soaking rain, over two dozen M. elegans magically sprang up in gregarious clusters from a bed of decomposing wood mulch and leaf litter in my yard. Its genus name, Mutinus, refers to the Roman phallic deity, and its order name is Phallales, as one might expect. For obvious reasons, it’s commonly called the Dog Stinkhorn, Headless Stinkhorn and the Devil's Dipstick. A related and frequently mistaken species, Mutinus caninus, is more reddish in color and smaller. 

They're both edible but hardly tempting, although they've been used in potions and ointments for gout, epilepsy and gangrenous ulcers and fed to cattle in parts of Europe as aphrodisiacs (no surprise). Not uncommon among fungi (Penecillium is the best example), the stinkhorn possesses antibiotic (anitbacterial and antifungal) properties.

And plants at whose name the verse feels loath,
Filled the place with a monstrous undergrowth.
Prickly, and pulpous, and blistering, and blue,
Livid and starred with a lurid dew.

From "The Sensitive Plant" by Percy Bysshe Shelley, 1820.
The poet is "loathe" to include the name stinkhorn in verse.

The somatic phase of growth begins with the stalk's (stipe) emergence from a partially-submerged, creamy-white, two to three centimeter, egg-shaped volva that is attached to the soil by a thick mycelial cord. Within hours, the capless mushroom acquired almost five centimeters of height. The jaw-dropping spectacle is accomplished so quickly since the stinkhorn is fully-formed in a compressed state within the "egg" - its appearance related more to expansion than cellular growth. The stinkhorn's slightly curved and erect body is hollow internally with an orange peel-like, spongy external surface that is punctuated with minute interconnecting chambers. 

During the reproductive phase of growth, which quickly follows, the apex of the stalk becomes smeared with an olive-brown, fecal-smelling, mucilaginous slime (gleba). The malodorous goo is enriched with spores produced within the volva and passively exudes from a small opening at the tip during its erection. The lively color of the stinkhorn is visually enticing to insects as is the gleba, which is an offensive olfactory mix of skunk-smelling methylmercaptan and rotten egg-infamous hydrogen sulfide. The gelatinous mass of spores irresistibly attracts mycophagous (fungi-eating) insects such as the metallic-colored Bluebottle fly that traipse through and ingest it.

Rather than relying on wind and gravity to disperse the spores, the two commonest dispersal modalities for all fungal spores, the appendages and bodies of insects serve as vectors of dissemination. Called entomophilus dispersal, the cache of spores are unknowingly removed during its grooming elsewhere. Spore ingestion may also contribute to dispersal, since they're acid resistant and can germinate elsewhere following defecation.

In a day or two with its reproductive obligation fulfilled, the fruiting body has begun to wither, becoming limp and flaccid with little remaining gleba, yet a lone fly is still attracted by the fetid scent. Off to the left, also promoted to germinate by the wet weather, a bevy of tiny cup-shaped Bird's Nest fungi are awaiting the next rain to facilitate spore release via a uniquely different mode and dispersal mechanism.

Sprinkled around the stinkhorns and easy-to-miss by virtue of their tiny 3/8th inch-diameter, Bird's Nest fungi easily can catch the eye by their grouping into tight clusters on rotting wood mulch. Its fluted fruiting body resembles a miniature bird's nest replete with eggs, which are lens-shaped periodoles - packets of millions of spores and the specialized cells that form them. The "nest" (peridium) is a cup-shaped structure that quickly loses its membranous, lid-like cover structure (epiphragm) upon germination. 

Cyathus Striatus - A Master at Spore Dispersal
Initially, Bird's Nest fungi have immature fruiting bodies that are spheroidal with a hairy projections on the exterior and contain lens-shaped periodoles that contain spores. a striated interior.  When mature, the mushrooms rupture exposing the striated namesake-interior and appear like tiny eggs with spores enclosed within the protective sac of the periodole "eggs." They fruited in concert with the stinkhorns and like them, are saprophytic - enzymatically feeding on decomposing organic remains.

As do plants, fungi utilize two modes to extend their range: growth into a neighboring area, which is a slow process (fairy rings are an example) or the dispersal of spores utilizing various vectors. Compared to seeds, spores are microscopic (~2-5 μm), lighter, less dense and more aerodynamically-designed and can travel considerable distances via the wind - the dispersal vector to which most spores subscribe. 

The Mushroom is the Elf of Plants-
At Evening, it is not-
At Morning, in a Truffled Hut
It stop upon a Spot

From "The Mushroom is the Elf of Plants" by Emily Dickinson

A region of micro-still air surrounds the spore-producing gills of mushrooms, which spores that rely on the wind for dispersal must first clear. In addition, most fungi are below the thin, non-turbulent "boundary layer" of air at ground level. When air flows over a surface, such as the ground, friction reduces current flow and creates a transition zone of calm air between the two stable systems. In order to become airborne, many fungi have developed highly creative mechanisms for assisting spores to penetrate through the layer in order to utilize the wind for dispersal.

A Cluster of Bird's Nest Peridia Filled with Lens-Shaped Periodoles Awaiting the Next Rain
The Bird's Nest mature fruitbodies are cone-shaped and covered externally with shaggy, dark brown hairs, whereas, the inside wall is smooth, striated and gray and filled with lens-shaped periodoles. The fungus typically fruits on beds of decomposing woody mulch.

C. striatus has adapted to the problem of both discharge and dispersal beyond the boundary layer via ballistospory, by literally catapulting spores into the air. The Bird's Nest's "splash-cup" mechanism is accomplished when one-eighth inch raindrops travelling at 13 to 26 fps strike the cup and eject periodoles a foot or two from the "nest." Each periodole is attached to the cup's inner wall by a cord-like funiculus, which tears from the cup and serves as an attachment mechanism by entangling a sticky holdfast called a hapteron to a nearby plant. Once above the boundary layer, wind currents disseminate the spores. Voila!

The Innovative "Splash-Cup" Mechanism for Releasing and Dispersing Spores
 (A), Forceful raindrops strike the peridium; (B), Periodoles are ballistically ejected through the boundary layer; (C), The holdfast attachment snares onto anything in its trajectory; (D), Spore release and dispersion follows. 

Modified Images and Courtesy of Nicholas Money, Professor of Botany, Miami University.

Both M. elegans and C. striatus are members of phylum Basidiomycota. Along with larger, sister-phylum Ascomycota ("sac fungi"), they are members of the "higher fungi" sub-kingdom Dikarya, which is contained within Kingdom Fungi. Basidiomycetes (a non-taxonomic, obsolete class but convenient and informal term) produce most of the large fruiting bodies found in nature - the specialized reproductive structures that house basidia such as mushrooms, puffballs, bracket fungi, yeasts and so on. 

Its members largely reproduce sexually via specialized cavate (club-shaped), microscopic spore-producing and spore-bearing cells called basidia that typically blanket the gills located outside the fruiting body such as found on the underside of mushrooms. In the case of the Dog stinkhorn's volva and Bird's Nest's periodoles, spores mature inside the fruiting body instead of discharging them directly into the air. The internal production of spores accounts for the number of creative ways they are released in order to "get them outside." The gasteroid fungi were originally classified as gasteromycetes or "stomach fungi", another obsolete term of reference since many members are unrelated.

Cross-section of a Mushroom
Modified from 

Fungi are constructed of a thread-like network of mycelia (pl.). It's the whitish, fuzzy cobweb-like growth found on the forest floor beneath an overturned log. The mycelium permeates throughout the body of the fungus. On a microscopic level, it's comprised of an interconnecting and branching mass of tubular cells called hyphae (2-10 μm in diameter) that are responsible for the growth of the fungus and its nutrition. The hyphae and mycelium channel nutrients to form fast-growing fruiting bodies. 

SEM of Fungal Mycelium and Basidia with Spores
(Left), Mycelial mass of interconnecting and branching hyphae. It's role is to penetrate
(Right), Scanning Electron Micrograph of basidia and associated basidiospores. Basidiospores have a single haploid nucleus. 

Mutinus elegans typically appears on decomposing woody substrates, which makes it saprobicobtaining nutrition from a dead or dying host. In contrast, plants are autotrophic, capable of providing and creating their own "food" (glucose) by converting carbon dioxide and water in the presence of sunlight (photosynthesis). Fungi and animals are heterotrophs, obtaining nutrition from their surroundings by secreting enzymes that break down (decompose) complex molecules into smaller, more absorbable compounds. Fungi digest foods externally via "chemoheterotrophic extracellular digestion" and then absorb it versus animals that ingest foods and digest it internally. Fungi are often parasiticderiving nutrition from an unhealthy substrate such as a tree, and can continue as saprobic, after the host succumbs (or contribute to its demise). 

Along with soil bacteria, fungi are the great decomposers and recyclers of our terrestrial ecosystem. The disassembling of large organic molecules into simpler forms is a vital process that nourishes other life forms by re-entering the food chain. Without rot and decay there would be no life.

Fungi's Essential Role in the Ecosystem
The complex organic molecules of detritus (dead plant material, animal remains and fecal material) are broken down by decomposers such as fungi, bacteria and earthworms into inorganic derivatives such as carbon dioxide, water and minerals (such as nitrogen and phosphorus). Fungi decompose organic matter by releasing enzymes, after which they absorb nutrients made available within the decaying material while returning (recycling) carbon and nutrients to the ecosystem for other living organisms such as vascular plants for growth and replenishing carbon dioxide to the atmosphere.
Modified from

The study and classification of fungi - mycology - was initially a naked-eye endeavor based on morphology and reproductive structures. It was originally a branch of botany, although fungi were always recognized as different from plants. The science became more exacting with the invention of the light microscope in the 16th century and far more precise with the advent of SEM (Scanning Electron Microscopy) and molecular genetics in the 20th century. It led to the placement of all fungi within Kingdom Fungi of which taxonomists have classified perhaps 140,000 types, but the numbers suggest that only 10% are known.

Fungi were originally included within Kingdom Plantae based on anatomical and lifestyle similarities such as vegetative growth (the period between germination and reproductive stages), nonmotility (rendered via firm attachment to a substrate), rigidity (although fungal cell walls contain the rigidity-conferring, carbohydrate-polymer chitin occurring in arthropod exoskeletons, whereas plant cell walls are made of cellulose and animals lack a cell wall) and seed-like spores (superficially similar to plant seeds but fungal spores are immensely different and of course animal seeds are gametes and totally different). Remember that superficial resemblances are not a reflection of phylogeny, only convergent evolution

Many Aspects of Fungal Growth are Plant-like
The striated and gilled mushrooms of Mycena leaiana are visible with the naked eye, and are thus classified as macrofungi, which are largely found in subdivisions Basidiomycota and Ascomycota, although many are capless. Growing laterally from the forest floor in clusters, Mycena, like many mushrooms, orient themselves via negative gravitropism (plants orient to the sun called phototropism), so that the spores fall directly downward but above the boundary layer. It also protects the developing spores from rain. Fungi are also capable of plagiotropism, in which the apical portion of the stem bends upward towards vertical and not just at the base.

Unlike plants, fungi lack true roots, stems and leaves, lack vascular tissue as do plants, and don't possess chlorophyll, and therefore can’t manufacture food via photosynthesis as do plants. And unlike seeds, spores are microscopic, unicellular, produced in far greater numbers and don't contain miniature plant embryos and food stores. Seeds and spores share haploidy and diploidy conditions (half and normal chromosomal numbers), but there are major differences regarding the ultimate goals of sporogenesis - mass production of spores versus fewer spores but with genetic variability (explained in post Part I here).

Fungi and the Phylogenetic Tree of Life
The three-domain system of life (Carl Woese, 1990), which uses ribosomal RNA protein sequences, adds a level of classification "above" kingdoms and divides life forms into Bacteria, Archaea and Eukarya. All life is theorized to have evolved from a "universal common ancestor." First classified as plants, fungi (red arrow) are thought to have diverged from plants and animals but are more closely related to the latter. Fungus-like slime and water molds, although structurally similar to fungi, belong to Kingdom Protista (Protoctista). Unlike single-celled bacteria and archaea that are prokaryotic (lack membrane-bound cellular organelles) and are classified within separate domains, fungi, like plants and animals, are eukaryotic (contain membrane-bound organelles, especially a nucleus).
Modified from Biology of Plants, Seventh Edition, W.H. Freeman and Company, 2005

Most of the scientific community believes that dinosaurs and birds are phylogenetically related, as are mammals and reptiles, apes and humans, and so on. They all belong to Kingdom Animalia and, along with plants, are eukaryotes (organisms with cells that contain membrane-bound organelles, especially a nucleus). So, how are plants, animals and fungi related being in separate kingdoms? Is there a common ancestor?

Although relationships are unresolved, molecular analyses suggest a three-way split between between fungi, plants and animals estimated at 1,576 +/- 88 Ma and that fungi and animals were derived from a common ancestor that existed ~1 billion years ago. Subsequent to that, terrestrial colonization of land by fungi remains somewhat speculative and obscure (see Prototaxites below). No ancient fossils exist, since fungi don't biomineralize (produce preservable minerals within biological tissues). 

Plants and fungi exist in symbiotic relationships that are thought to have developed long ago. Co-operative interactions with fungi may have helped early plants adapt to the stresses of the terrestrial realm. Thus, it's likely that fungi were on land with plants in the Devonian, although molecular clock estimates indicate fungi gained ground earlier in the Cambrian. 

Fungal Columns of Prototaxites Dominate a Speculative Landscape
Although alternative older views suggest it was a large vascular plant, it is currently thought that, in the Late Silurian to the Late Devonian, Prototaxites formed large trunk-like structures up to 1 meter wide and 26 feet high, the largest organism of the period. It possessed a tubular structure identified in fossils most like fungi of phylum Glomeromycota and must have had an extensive mycelium to have obtained sufficient organic carbon to accumulate the necessary biomass for the giant fungus.
Used with permission from scientist F. Hueber (who redescribed Prototaxites as a fungus in 2001 after 20 years of research). Painting by M. Parrish with permission and courtesy of the Smithsonian Institution.

Commonly referred to as the Jack-O-Lantern mushroom, for obvious reasons, and the fact that it fruits in the fall, Omphalotus illudens is saprobic, in this case deriving nourishment from the roots of an unhealthy acacia tree. It's typically found in large clumps on decaying wood, buried roots or at the base of hardwood trees in eastern North America. Its agaric (mushroom-shaped fruiting body) is bright-orange with decurrent (descending on the stalk) gills (thin plates beneath the mushroom cap that contain spore-producing basidia). Don't be enticed by the seductive, culinary beauty of the mushrooms. They are extremely poisonous when ingested!

Omphalotus spores are gravity-released from the undersurface of the fruiting body, which allows wind currents to disperse them called anemophilous dispersal. The large number of mushrooms in clusters (many of which reach six inches in width) and the massive numbers of spores that are generated (a large mushroom can shed 40 million spores per hour) better the odds that at least a few spores will germinate somewhere downwind if the conditions are right. How do the spores get off the gills and away from the mushroom cap?

All members of phylum Basidiomycota, such as the Dog Stinkhorn, Bird's Nest and Jack O'Lantern fungi, possess spore-producing basidia cells. As mentioned, they line the gills on the undersurface of mushrooms or equivalent reproductive structures. Each spore secretes a small amount of sugar that absorbs moisture from the humid air around the gills, which condenses on the spore's surface in a thin film. Condensed water also forms a tiny Buller's drop at the base of the spore at the sterigma, a tiny extension of each basidium (sing.) As the drop gradually increases in size, it suddenly contacts the film and quickly collapses as it "feeds" additional moisture to the spore's surface. 

The micro-event shifts enormous mass to the spore providing sufficient momentum to accelerate the "ballistospore" 25,000 times the force of gravity and discharge it through the micro-thin boundary layer of air around the gills to the wind. By comparison, the NASA Space Shuttle possesses a maximum acceleration of only a few times the force of gravity. The mechanism of ballistospory is utilized in many unrelated mushroom groups and is the result of parallel co-evolution.

(Top), Time-Lapse Photos of Micromechanical Forcible Discharge of a Spore Using a Buller's Drop
The transfer of energy from the drop to the spore releases the spore from its supporting structure. During the early phase of coelscence process, the sterigma provides the external force that prevents the spore from moving toward the drop. In the late phase of the coalescence process, the sterigma is now put under tension and should fracture easily to prevent dissipation of the spore energy. The kinetic energy of the spore after ejection ejects it through the boundary layer. 
From Xavier Noblin et al, 2009.
(Bottom), High-Speed Video Imaging Demonstrating Ballistospore Discharge
From YouTube

There is no known analog in nature of this unique, musculature-less, micro-mechanical process in animals, plants or bacteria. The production of many trillions of spores ensures that some will survive once dispersed by the wind. Some basidiomycetes lack forcible discharge such as the stinkhorns that use insect vectors, which is considered an evolutionary loss ancestral to all basidiomycetes.

Subsequent to genetic investigation, many coprinoid fungi - all members of Basidimycota - have been reclassified, many with a name change. In fact, binomial scientific names of all fungi often change with the advent of more refined genetic analyses. This is true especially of "gill" fungi. 

With Parasola plicatilis, the group acquired the coprinus genus name, because they frequently "live on dung", while plicatilis in Latin means "folded" or "wrinkled". Although this sole, delicate beauty fruited one morning on wood chips, they are also purported to live in grassy areas and forest litter. With a delicate, long stalk, cover of tiny hairs and a gracefully unfurled parasol, P. plicatilis doesn't remain too long in the heat of the day. There's a reason, and it's related to spore release and dispersal. 

As the mushroom matures, the stem begins to rapidly elongate followed by liquefaction of the cap and gills within hours via the mushroom's autolytic enzymes. "Self-digestion" allows the mushroom's black spores to release to the wind, facilitated by the elongate stalk well above the boundary layer. The blackish goo that forms following lysis provides the group's more common name "inky caps", which actually can be used for writing. 

This common perennial, semicircular-shaped, large fungus protrudes in a shelf-like manner from its host, a rotting stump. G. australe's spores are produced inside tiny, rigid tubes rather than gills that line the underside of the fruitbody. They open to the exterior and lend a perforated appearance to the fungus, hence the species common name polypore and bracket fungus due to its shelf-like growth on the sides of trees and stumps. Unlike mushrooms that morph into a putrefying mass in days following the reproductive phase, bracket fungi can last months, through winter and some years owing to their woody consistency.

Various Spore-bearing Surfaces Under Caps
Modified from

It's parasitic in early stages (fungal tree pathogens produce biodelignification or white heart rot in oak, birch, beech, chestnut and a few others) and becomes saprobic as the host dies (which can have enormous economic and environmental impact). They're commonly called "conks", because the fungal "wood" is corky in texture with a tough, leathery and shiny surface (ganoderma means "shining skin"). Not surprisingly, they're inedible, although some members of the genus have been used to make tea and for medicinal purposes in China and Japan for thousands of years. 

With a drab, brownish uppersurface, the brilliant white, rounded collar and undersurface are an indication that brown spores are ready to be released by basida that line the tubuli. Succumbing to gravity, they have colored the fruiting body, adjacent bark and underlying soil with a fine, brown dust upon their release. You can even ascertain the direction of the prevailing wind to the east from the color of the adjacent bark.

The Shelf or Bracket Fungus Ganoderma Australe
Growing on trees that are naturally elevated from the ground, a stalk is unnecessary to elevate the fruiting body above the boundary layer's still air. Success of germination is ensured by the enormous number of spores that are generated over the many years that the fungus can live, which often can be calculated by counting the growth zones or furrows on the cap as the cap extends outward and downward. 

In contrast to mushrooms and like the aforementioned stinkhorns and bird's nest fungi, S. citrinum produces spores inside the fruit body. It's often confused with puffballs, which are soft and spongy when ripe, Scleroderma ("hard skin") citrinum is an earthball fungus. Superficially, the two are similar but are unrelated. Also known as Common Earthball or Pigskin Poison Puffball, it's typically found found solitary or in groups in the woods on rotten wood and leafy, twiggy ground. 

Because they are often partially buried, they have been mistaken as truffles, a non-farmable ascomycete fungus that is highly prized for its culinary attributes. That would an unfortunate mistake for the forager, since earthballs have an unpleasant flavor and are mildly poisonous causing GI disturbances, chills and sweats. It would be financially beneficial to recognize the difference in the field, since this year a 4.16 pound white truffle sold at a Sotheby's auction for $61,250. And yet, it was a bargain, since abundant rainfall in Italy has produced a bumper crop that brought prices down.

S. citrinum is yellow-brown in color and covered with a scaly raised and ornamental mosaic of attractive brownish geometrics on its tough, rind-like peridium (skin). It typically has an ellipsoid or globose (round) to pear-shaped fruit body that contains trillions of spores that develop within locules (small cavities or glebal chambers). Unlike puffballs that are saprotrophs, earthballs are mycorrhizal ("fungus-root"), entering into a symbiotic relationship with vascular plants. 

In fact, over 90 percent of all plant families are known to partner with mycorrhizal fungi. By doing so, the fungus provides increased water and nutrient absorption while deriving carbohydrates formed from photosynthesis. It often explains why crops fail and why a newly planted sapling doesn't "take." Gardeners recognize this from their active use of compost.
Typical Fine-Branching Mycorhizzal NetworkContrary to one's common perception, the white fungal network of hyphael cells in intimate contact (ectomycorhizzal, outside of root cells and penetrating within, endomycorrhizal) with the roots of vascular plants and trees is responsible for the uptake of nutrients, not the plant roots.
From and illustrated by Michael Rothman

S. citrinum's is a member of Basidiomycota, but unlike mushrooms it's spore-producing basidia cells line and mature within the puffball's enclosed, globular interior. It's 
considered to be a gasteroid ("stomach") fungus for obvious reasons. Puffballs, when provoked by rain, implode and release trillions of spores to the wind in a powdery, smoke-like puff through a small aperture on the the superior surface of the fruiting body. On the other hand, earthballs, which also rely on a massive release of spores, develop fissures when ripe in order to release their bounty.

Instead of parasitizing or scavenging other organisms, some 13,500 fungi to date have discovered farming by being intimately involved in a symbiotic relationship. It's a mutualistic and intimate partnership with dissimilar organism(s). The affiliation allows the lichen to endure extremes of temperature, nutrient availability, solar radiation and aridity, seemingly everything adversely environmental with the exception air pollution. As a result, lichens are typically not found in big cities ("lichen deserts") and industrial regions due to high levels of sulfur dioxide.

There is a low mist in the woods—
It is a good day to study lichens.

From A Year in Thoreau's Journal by Henry David Thoreau, 1851.

The interdependent partnership is between a mycobiont, a lichenized fungus (the major partner and usually a member of Ascomycota), and a photobiont, a green alga or cyanobacteria (formerly called blue-green algae) or both. The mycobiont derives organic molecules (generally simple carbohydrates such as glucose) from photosynthesis carried out by the photobiont, while the alga is protected against desiccation and excessive solar radiation, and receives mineral nutrition from the mycobiont's atmospheric and substrate surfaces. Cyanobacterial partners provide nitrogen to its fungal partner.

Schematic Cross-Section of a Typical Foliose Lichen
Arranged in a layered sheet-like manner, a foliose lichen's thallus consists of: 1.) A colorful upper cortex of interwoven, highly-compacted, physically-protective ultraviolet light-filtering pigment of fungal hyphae); 2.) A green or blue-green algal photosynthesizing photobiont surrounded by the strands of the mycobiont; 3.) A spongy, middle medulla of loosely-packed, thread-like hyphae; 4.) A lower cortex of; 5.) Anchoring hyphae on the substrate (rhizines) without vascular capabilities like plants. The thallus of a lichen is the vegetative, non-reproductive "body" of the lichen. Other lichens possess a somewhat different morphology such as a missing lower cortex.
Modified from Wikipedia, artist JDurant and

Very common in deciduous woods and forests of New England, foliose Punctelia appalachensis is accompanied by various tiny crustose lichens was growing on a rotting log in my back lot (below). The lichen has a greenish, mineral-gray thallus (vegetative body) with divided lobes and non-ciliated ("hairy") margins. Notice the green photosynthetically-active center section. That classifies it as a chlorolichen, whereas a lichen with a cyanobacterial partner is a cyanolichen

A Large Foliose Lichen Shares a Decomposing Log with Numerous Diminutive Squamulose Forms
This Punctelia appalachensis is covered with spores. Lichens are found in many growth forms: foliose (leaf-like lobes that are easily removed from the substrate), fruticose (shrubby or pendant), crustose (most common, crust- or coral-like and firmly-anchored by root-like rhizines), leprose (powdery) and squamulose (scale-like lobes).

Lichen reproduction is not a straightforward event, since lichens consist of two or even three distinct organisms that each participate in the process. Lichens reproduce asexually utilizing openings on the thallus called soralia that contain dust-like granular particles (soredia) and that contain fungal and algal cells from the parent lichen and grow into a new thallus. Alternately, tiny, cylindrical projections (isidia) on the surface that incorporate both mycobiont and photobiont can easily break off (fragmentation) and grow elsewhere on a suitable substrate.

Sexual reproduction occurs when lichens produce miniature-appearing, cup-shaped fungal fruiting bodies (apothecia) that contain spores and require the appropriate photosynthetic partner to lichenize. Our Punctelia specimen, being a member of Ascomycota (the other higher "true fungus" along with Basidiomycota and the most common mycobiont), asexually produces ascospores that take to the wind for dispersal. 

By the way, symbiosis exists between many other life forms. Jellyfish contain an alga (zooxanthellae) within their tissues as do reef-building coral, neither of which can survive on their own. It explains why jellyfish frequently swim inverted or dwell in shallow sunlit waters within the photic zone. Lichen's fungal members can't live and grow without their communal partner and are never found in nature without it, whereas, the photobionts, whether algal or cyanobacterial, can survive independently in nature. 

This post is dedicated to botanist, geologist, naturalist and fellow blogger Hollis Marriott, who always seems to like it when I post on something that grows. Please visit her blog par excellence "In the Company of Plants and Rocks" (here).

• Kingdom Fungi by Steven L. Stephenson 
• Macrolichens of New England by James W. and Patricia L. Hinds
• Mushroom by Nicholas P. Money 
• Mushrooms Demystified by David Arora
• Mushrooms of Northeast North America by George Barron 
• Mushrooms, Simon and Schuster’s Guide by Gary H. Lincoff

•  A Higher-Level Phylogenetic Classification of the Fungi by David S. Hibbett et al, Mycological Research III, 2007 (here).
•  Field Guide to Common Macrofungi in Eastern Forests and Their Ecosystem Functions by Michael E. Ostry et al, U.S. Forest Service, 2010 (here).
•  Mycelium Running by Paul Stamets, Ten Speed Press, 2005 (here).
•  Towards a Natural System of Organisms: Proposal for the Domains Archaea, Bacteria, and Eucarya by C.R. Woese et al, Proc. Natl. Aca. Sci., June 1990 (here).
•  Weathering of Rocks Induced by Lichen Colonization — A Review by Jie Chen et al, Elsevier, Catena 39,2000 (here).
•  Surface Tension Propulsion of Fungal Spores by Xavier Noblin et al, The Journal of Experimental Biology 212, 2009 (here).

Sunday, September 4, 2016

Death Valley Geology Calling: Part I - Where Is It? What Is It? What Isn't It?

"Death Valley is the Grand Canyon put into a juicer and minced!" 
Geologist, Author and Guide Wayne Ranney, 2016

Over the course of almost two billion years, the Death Valley region has experienced a long and varied series of geologic events with each progressively adding complexity to the former. They include the fragmentation of two supercontinents - Rodinia in the Late Proterozoic and Pangaea in the Mesozoic - at least four episodes of major volcanism, three or more intervals of marine deposition - one in the Late Proterozoic, another during the Paleozoic and a third during the early Mesozoic - at least four prolonged periods of large-scale tectonic deformation and two or more low-latitude, global glaciations in the Late Proterozoic. 

Beginning in the late Mesozoic, tectonic compression led to severe and widespread crustal extension in the late Cenozoic across western North America's Basin and Range province including Death Valley. Extension is thought, in part, to have operated synchronously under the influence of two superimposed stress fields, one tectonically-controlled and the other gravity-induced. 

Iconic and Photogenic Zabriskie Point Badlands Overlooking Death Valley
Beginning ~14 million years ago, before the lowering of adjoining Death Valley, Furnace Creek basin developed in response to right-lateral displacement along the Furnace Creek fault and detachment faulting along the northern part of the Black Mountains. The rhombochasm downdropped during middle Miocene to Pliocene time between the uplifting Funeral Mountains to the north and the Greenwater and Black Mountains to the south. As the northwest-elongated half-graben opened parallel to the Funerals front, the depocenter received Artists Drive, Furnace Creek and Funeral Formations in succession. On display at Zabriskie Point are colorful layered mudstones, siltstones, alluvia and ash of the Furnace Creek Formation that, upon exposure and uplift, have eroded into rills, gullies and extension-tilted badlands. The sentinel peak of Manly Beacon (right) overlooks Death Valley's Badwater Basin (center) and the Panamint Range (background). In the early 20th century, Christian Brevoort Zabriskie was the VP and GM of the Pacific Coast Borax Company. This photo was post-processed with tone mapping. Go there (36°25'12.49"N, 116°48'44.03"N).

Death Valley's landscape lies in contrast to the Grand Canyon in nearby northern Arizona. Their crystalline basements and sedimentary successions formed under closely related orogenic, rift-to-drift and Cordilleran miogeoclinal circumstances, but the Grand Canyon's rocks have remained uplifted, untilted and largely undeformed. If it wasn’t for the fortuitous erosive action of the Colorado River system, they would not have been exposed. 

Death Valley, on the other hand, possesses a diverse, complicated and beguiling terrain with a distribution of rocks that are variably faulted, folded, deformed, mangled, chaotic and nothing less than a challenge to interpret. In addition to being relatively uneroded, unobstructed by vegetation and unmarred by glaciation, extension has provided a landscape that is well exposed and highly accessible.

Tortured South Wall of Titus Canyon in the Grapevine Mountains of Northeastern Death Valley
With the exception of aptly-named Amargosa Chaos of southern Death Valley, perhaps nowhere else in the region better demonstrates the cumulative complexity of geological events experienced by the landscape than on a drive on Titus Canyon Road through east-west trending Titus Canyon in the Grapevines along northern Death Valley’s northeast border. Late Proterozoic through Quaternary strata are exposed in the range with lowermost representing siliciclastic rift strata acquired during the fragmentation of the supercontinent of Rodinia and overlying carbonates, sandstones and shales deposited on the early developing Laurentian passive margin sequence. Factor in compression related to the development of the Cordilleran fold and thrust belt in late Paleozoic and Mesozoic time and Basin and Range extension in late Cenozoic time. The result can be seen in folded shale and limestone beds of the widely-distributed Middle Cambrian Bonanza King Formation that form the south wall of Titus Canyon in the vicinity of the Leadfield Mine. Yet, the wall is even more tortured than it looks. The rocks are completely upside-down, so the oldest rock in the fold is in the core --which makes it an anticline. You can't tell that from the photo, but you can tell it by following the stratigraphy down the canyon. Therefore, it’s a synformal anticline. Think of it as an anticline (where the rock layers get younger away from the axial surface of the fold) that has been inverted, but it has the shape of a synform (with a trough-like shape). Multifolded stratigraphic layers such as this are typical of collisional environments. From the air, the upturned, upfolded (anticlinally), downfolded (synclinally) and recumbant folds (turned back on itself) of Titus Canyon make more sense. Visit Marli Miller (here) for a great perspective. Thanks for the help with the clarification, Marli!

In mid-winter 2016, our intrepid party of four, under the guidance of geologist and author Wayne Ranney (here), explored Death Valley from its heights to its depths. Our plan was to investigate the geology, experience the region's otherworldly aura, beat the heat and precede the throngs that arrive to see the colorful wildflowers that typically appear in spring. We succeeded on all accounts and, to our delight, arrived in the midst of a once-in-a-decade spectacular "super-bloom" spawned by El Niño rains in October. 

Helen is Regaled in the Midst of a Wildflower Superbloom
In the shadow of Copper Canyon Turtleback along the Black Mountains front on Death Valley's east side, the gently sloping, spring-fed apron of an alluvial fan provides fertile ground for a new carpet of Desert Gold wildflowers. To withstand the dry blistering heat, they blossom for only a short time and go to seed after just a few weeks. Lying dormant for years, they patiently await the appropriate conditions to germinate. The average annual rainfall in Death Valley is barely two inches, but October 2015 El Niño storms brought a deluge that exceeded that in one day. In February, over 20 species of spectacular wildflowers joyously appeared to celebrate the event. Go there (36°04'45.85"N, 116°45'50.63"W).

This is my first post of three on the geology of Death Valley. It begins with a compilation of some of the region's most vexing questions, many of which remain unanswered and hotly debated. It is followed by a discussion of the region's geographic and physiographic location in western North America. Part II presents a synopsis of Death Valley's geological evolution beginning with the acquisition its basement rocks in the Early Proterozoic. Part III offers a few examples of profound biologic resilience when confronted by Death Valley's environmental extremes and of the diverse human and mining history scattered about the region. Global co-ordinates have been added to each post that, when copied into a mapping program such as Google Earth, will allow you to "Go there."

Our Party of Four (Minus Me) at Ubehebe - Wayne, Helen and Dee
Late afternoon sun casts long shadows into erosion-gullied "big basket in the rock", named by the regional Timbisha Shoshone Native Americans. Ubehebe Crater is one of a dozen or so shallow maars in northern Death Valley volcanic field that erupted phreatomagmatically - a violent explosion of tephra and steam when magma contacts ground or surface water. Uppermost 50 or more beds of unconsolidated ash and fragmented bedrock overlie beds of tilted and faulted, iron oxide-stained, lower Miocene-age alluvium derived from the Grapevine Mountains. Passive volcanism in graben structures such as Death Valley is common and is related to a thinned lithosphere with alkaline magmas sourced from the partial melting of lithospheric mantle. Isotopic analyses of trace elements in the primary magma reveal a Precambrian mantle source in the Mojavia subcontinental lithosphere, suggesting the terrane genesis that formed the Death Valley region (see post Part II). Dating methods indicate a Holocene age of 2,000 to 7,000 years (one recent study found 300 years), recent enough to be considered active and potentially hazardous. It's a reminder that Death Valley's climate was once wetter, when pluvial lakes attained their peak size, and that the calm and motionlessness of the landscape was intensely interrupted in the recent past. Go there (37°00'35.12"N, 117°27'03.14"W).

When conversing with individuals unfamiliar with its location - with the exception of geologists, residents of the Southwest and baby-boomers who watched Death Valley Days on television when they were kids - the most common questions are "Where is it?" and "Isn't it a desert?" The uninformed are gratified to learn that it is a desert but are surprised to discover that barely 10% of its surface is covered with sand. But, deserts are defined by lack of rainfall, not surface composition or elevation. And they're not all hot. In fact, the two largest deserts on Earth are located at each of the poles - sandless and frigid. In addition, they are astounded to hear that Death Valley is flanked by spectacular mountain ranges, some snow-capped and some that tower almost two miles above the desert floor, which is below sea level. Lets investigate the geography.

And where is it? Simply stated, Death Valley is the geological centerpiece of Death Valley National Park in southeastern California along the southwest Nevada state line. The north-south basin of Death Valley is divided into three contiguous subbasins that vary somewhat in structure and timing of formation while sharing a commonality of extensional tectonics, from north to south: Cottonball, Middle and Badwater. They lie between the lofty Panamint Range on the west and the Amargosa Mountain Range on the east. The range-basin-range triad possesses a roughly N-S trend, in keeping with the alternating landforms of the Basin and Range physiographic province in which it resides.

The 110 mile-long Amargosa Range consists of three sub-ranges, from north to south: the Grapevine, Funeral and Black Mountains with the Ibex Hills in the south. Northeast of the Blacks, across Grand View Valley, stretches the smaller Greenwater Range that, along with the Funeral Mountains, defines intervening Furnace Creek Wash, a small basin that preceded the formation of Death Valley proper. State Route 190 follows the wash down into the valley from Death Valley Junction and Las Vegas further east.

Google Earth Image of the Death Valley Domain
Death Valley is bordered by the Panamint and Amargosa Ranges. The relationship of roughly north-south trending mountains and valleys - basins and ranges - that repeat across the landscape is characteristic and namesake of the Basin and Range province, while the endorheic hydrology, with waters that essentially are confined to each basin and never reach the open sea, is a characteristic of the Great Basin subprovince (see my post Part I for detailed explanations). Major roads in and out of the valley are labelled.

On Death Valley's west side are the Last Chance Mountains and the 100 mile-long Panamint Range. The latter consists of two sub-ranges: the Cottonwood and Panamint Mountains. The Owlshead Mountains are to the south. Beyond the Panamint Range to the west is Panamint Valley, and beyond that is Owens Valley - the westernmost valley in the Basin and Range province - and then the Sierra Nevada - the granitic mountainous spine of eastern California. On Death Valley's east side, beyond the Amargosa Range, lies the Amargosa Desert-Valley, and beyond that is Las Vegas Valley beyond the Spring Mountains.

Satellite Image of Death Valley
Flanked by mountain ranges on the east and west that embrace the desert floor, Death Valley extends from north to south for some 140 miles. Computer-enhanced, dark greens are forests of juniper and pine on high peaks that are still ascending, while the valley floor is filled with sediment, blanketed by alluvial fans that splay outward from the mountain fronts, scorchingly hot, dry as a bone and below the level of the sea - and still dropping! Various shades of brown and beige indicate bare ground resulting from varying mineral compositions in the surface. Appearing like limpid pools of water, bright blue-green patches are salt pans that hold little moisture on the surface. Below ground is a massive aquifer related to the region's hydrology and hint at a long-gone lake that once filled the valley in wetter times. Bright green circles off to the east are irrigation systems in Amargosa Valley. The south-flowing river in the lower right is the ephemeral Amargosa. It can be seen heading around the southern Black Mountains and then turning north into Death Valley where it terminates, typical of rivers in the region that never reach the open sea.
From NASA Earth Observatory and Landsat 7

Death Valley's Early Proterozoic crystalline foundation formed during the assembly of the supercontinent of Rodinia on which are deposited Middle and Late Proterozoic shallow-marine, intracratonic basinal carbonate sequences of the Pahrump Group and latest Proterozoic to Early Cambrian sedimentary sequences on the newly-established passive margin of Laurentia. The Precambrian-Cambrian succession was acquired during Rodinia's dissassembly and is one of the best exposed in the world. It was deposited at a time of dramatic change in the biosphere that included putative "snowball earth" glaciations, fluctuating oceanographic and atmospheric chemistries, long-lived mantle convection patterns, and large-scale plate reconfigurations that led to eukaryote diversification prior to the Cambrian Explosion of animals.

•  What is the theorized association between Rodinia's fragmentation, global climate deterioration and biological evolution? 
•  The Pahrump Group contains intervals of carbonate rock directly over suspected glaciogenic deposits. These "cap" carbonates are found globally during the late Proterozoic. The unusual and abrupt facies registers strong negative (depleted) carbon isotopic signatures often associated with extinction events. Most assign them an oceanographic origin with flooding of continental shelves and platforms as low-latitudinal ice sheets melted. Do glaciogenic deposits in Death Valley correlate to similar successions regionally and globally? Do they bear relationships to "snowball earth" glaciations, the Sturtian and Marinoan ice ages in particular?
•  The Late Proterozoic world is also thought to have possessed a number of equatorial Death Valley "Pahrump-type" and Grand Canyon "Chuar-type" intracratonic marine basins. What have we learned from them regarding rifting, paleo-climate and biological evolution? 
•  Distinctive 'fingerprints' such as lithostratographic and geochemical similarities, paleontological correlates and detrital zircon geochronology are used to match rifted margins. What have we learned regarding the configuration of Rodinia? If the rift zone was positioned somewhere between the margins of SW Laurentia and perhaps Australia, Antarctica or Siberia, where was Death Valley in the big picture?

Dante's Spectacular View of Northern Death Valley
Named after the Middle Age Italian poet for his references to hell in the "Divine Comedy", Dante's View lies atop Coffin Ridge on the western front of the Black Mountains, one of three ranges that border Death Valley's east side. Across the valley along the Panamint Mountain front, over a dozen alluvial fans have coalesced into a massive bajada. At its termination on the valley floor, shoreline deposits record the presence of long-gone and enigmatic, oscillating Pleistocene Lake Manly. A mile below our overlook, eerie whitish swirls are precipitated evaporites that coat the salt pan of Badwater Basin among brownish sediments eroded from the ranges. Far to the north are tan sand dunes of Mesquite Flat. The rugated, convex-upward slope in the foreground is Badwater turtleback, one of three controversial features thought to be a region of Proterozoic crust brought to the surface by large-scale extensional faulting. Go there (36°13.582’N, 116°43.545’W).

Crustal thickness in the Basin and Range province averages only 30 km compared to 50 km of the adjacent Colorado Plateau to the east. Yet, before its Cenozoic collapse its crust was actually thicker than the Colorado Plateau, since it was the site of the Sevier Mountains thrust belt acquired during Farallon plate compression. Death Valley's landscape is partially a consequence of widespread gravitational collapse of the Sevier-orogenic, over-thickened Cordilleran crust. It's also the result of the slab's demise beneath the western rim of North America, when an oceanic-oceanic transform plate boundary system "jumped" onto the continent and changed the structural fabric of the Southwest. 

•  How did the development of the Pacific-North American plate boundary effect the structure of Death Valley and the Basin and Range province in which it resides? 
•  Most rifts occur between diverging plates along mid-ocean ridges, such as the East Pacific Rise, while only a few are on land. Continental rifts, whether wide or narrow, form in extensional tectonic settings typified by crustal thinning, sedimentary basins, and thermal activity. Does Death Valley's extensional regime demonstrate these processes?
•  Los Angeles resides on the Pacific plate, along with an "acquired" slice of coastal California and all of Baja California. If continental rifting continues, what is the future of the western continent? Will a new ocean basin form? Will Death Valley also  "depart" from the North American plate or will it "remain" on the plate in the vicinity of a new passive margin, as it did when Rodinia was breaking apart?

Birth of the San Andreas Fault System
Beginning in the latest Jurassic, the Farallon plate began to subduct beneath the westward-migrating (present coordinates) North American plate, driven by the fragmentation of Pangaea and the opening of the Atlantic Ocean. The East Pacific Rise spreading center between the two oceanic plates was likewise drawn toward the Farallon-North American converging boundary. Following the Farallon's demise, the spreading center entered the zone, bringing the Pacific and North American plates into contact along the newly-formed Pacific-North American plate boundary. The event converted the Farallon-North American plate, which was an Andean-style subduction zone (mountain-building and magmatism) into the Pacific-North American transform boundary (horizontal plate motion without the generation of new crust). On land, the boundary is best known as the San Andreas fault system.
Modified from

Death Valley's landscape has undergone dramatic basin and range-style extension, consisting of a downdropped elongate basin flanked by bordering ranges. The ranges formed counterintuitively by crustal stretching rather than crustal compression, which typically drives uplift and continental volcanism. It has to do with strike-slip motion on the ~200 mile-long, north-south trending Death Valley fault system - a complex of zones, fault segments and strands that have been evolving over the past 14 million years. The system is confined to a relatively narrow zone from the northern end of Fish Lake Valley in Nevada, south along the entire eastern margin of Death Valley to the Garlock fault zone in California. The system's subdivisions include, from north to south: the Northern Death Valley, the Black Mountains and the Southern Death fault zones. The Furnace Creek fault system in Furnace Creek Wash branches southeast from the Northern system at the central basin and was a major player in the evolution of Death Valley in the late Miocene and Pliocene but largely inactive in the Quaternary. 

•  If the prevailing tectonic regime for Death Valley is strike-slip, how did the region extensionally "pull apart"? 
•  Furthermore, how did the mountain ranges ascend, if compression is generally required for uplift? 
•  Are the geodynamics ongoing? How do we know? What evidence of extension is there on the landscape that can be readily observed?
•  Why does Death Valley possess such extremes not only in relief but temperature and aridity?
•  For almost 150 years, the fact that topography in the Basin and Range province is controlled by normal faulting is recognized. But, what is the geometric behavior at depth of range-bounded faults as they dip beneath the intervening basins? Are some listric that dip steeply at the surface and abruptly flatten?

Fault Scarps and Tectonic-Induced Liquefaction in Alluvial Fan
Death Valley is bound by a system of relatively youthful, north-south trending active faults. The system extends over 200 miles valley along the mountain fronts on the valley's east side. John McPhee in his Pulitzer Prize-winning Basin and Range describes the system as "Basin. Fault. Range. Basin. Fault. Range. A mile of relief between basin and range." It's responsible for the region's astounding relief, varied landscape and even climate. Geomorphic features that affirm recent tectonic activity are abundant and observable, in spite of the fact that the faults are buried beneath thousands of feet of colluvia and alluvia. Immediately south of Badwater Basin and Badwater Turtleback, an alluvial fan that spills out from Badwater Canyon displays a series of eroded fault scarps (red arrow). Appearing as a series of eroded steps, they mark places where slip along the Black Mountains fault has displaced a portion of the fan. The fan is young geologically, which makes the faults even younger. Near the fan's terminus or toe, seismically-induced liquefaction (white arrow) has occurred in susceptible, unconsolidated and saturated coarse sandy gravel and sand that behaved in an aqueous manner. A series of deep, narrow grabens formed where the fan has extended by sliding downslope. On a large scale, liquefaction can be extremely destructive to population centers, especially in coastal and manmade fill-areas during earthquakes as small as magnitude five.

We frequently focus our attention on rapidly-moving, discrete faults where one or more continental plates interact such as the Pacific-North American plate boundary. Yet, a significant proportion of plate motion is also accommodated on complex, diffuse systems at hundreds to thousands of kilometers from interacting plate boundaries. Such is the case with the San Andreas fault system in coastal California, where of the 48-51 mm/yr of relative motion between the Pacific and North American plates, ~35 mm/yr is accommodated in a zone less than 100 kilometers wide or ~75%. The remainder of residual motion, some 15 mm/yr or ~25%, is distributed in a broad inland boundary of over a thousand kilometers wide in the Walker Lane belt, the Eastern California Shear Zone and the Basin and Range province.

•  How does the migration of strain transfer extensionally to Death Valley?
•  What is the relationship of Basin and Range volcanism to extensional tectonics? Is magmatism a passive response to crustal thinning or is asthenospheric upwelling (which accounts for the Basin and Range province's high thermal gradient, three times normal for continental areas) a trigger for extensional deformation? 
•  Do mantle processes such as a plume play an active role in promoting magmatism? Does a hot, buoyant mantle explain the province's high average elevation of 1,400 meters above sea level? Does that explain the magnitude of intraplate volcanism within the Basin and Range province? Where does Death Valley fit in?
•  Why does the Basin and Range province consist of a broadly-distributed region of strain instead of one or two elongate rifts of typical continental rifts? 
•  Does extension of the Basin and Range's orogenic (Sevier-thickened) lithosphere differ from extension of cratonic lithosphere?      

The Pacific-North American Plate Boundary in Southern California and Northwest Mexico
Jumping onto land, the spreading center converted the convergent plate boundary into a transform zone with dextral strike-slip, which reflects the northwest drift of the Pacific plate relative to the North American plate. The event terminated over 140 million years of continental compression in western North America with the exception of a few small Farallon remnants). , captured a sizable slice of coastal California for the Pacific plate, tore Baja California from mainland Mexico, opened the Gulf of California and initiated ongoing extension across the landscape of western North America including Death Valley. Today, Pacific-North American plate motion is distributed across the western United States primarily along the San Andreas system and the remainder in seismic zones to the east. The transform fault system, rather than linear in strike, warps and bends which produces transpressional and transtensional regions along its path. Death Valley is the type-example where lateral motion has given way to a transtensional pull-apart basin manifested by faulted mountain fronts, tilted and uplifted ranges, extensive saline playa, metamorphic core complexes and spectacular alluvial fans.

Modified from, Rymer et al, 2002 and Fuis, 2003.

Death Valley is actually composed of three contiguous sub-basins, from north to south: Cottonball, Middle and Badwater. Their formative and structural histories differ, but they share a commonality of tectonic extension. The northern and southern sub-basins are parallel and trend roughly northwest, while the center sub-basin trends north to south. Faults in the north and south are strike slip, whereas those in the center are largely normal faults with oblique components. 

•  How did they evolve? Did they do so coevally?
•  How can strike-slip and normal faulting co-exist in one fault system? Is there an interplay? What's a pull-apart basin? What's a rhombochasm?
•  What is the relationship of Furnace Creek Basin to the adjoined younger and lower basin of Death Valley?
•  A relatively small Holocene-age volcanic field called Ubehebe lies in northern Death Valley. The field's eruptive style is phreatomagmatic - amagmatic explosions of steam and ash rather than effusive emanations of lava. Whether subterranean or surficial, where did all that water come from? Does the eruption imply a wetter paleo-climate for the region or was the abundance of water related to an underground remnant of paleo-Lake Manly that once filled the entire valley?
•  Mesozoic and Tertiary volcanic and intrusive rocks are found in Death Valley basin and some ranges. What's their genesis in regards to the region's evolutionary history?
•  On a grander scale, the relationship and interplay of tectonics and magmatism in the Basin and Range province has been a topic of long-standing debate. Is there a relationship between extension and magmatism in the Basin and Range province and Death Valley? Does it play an active role in extension or is magmatism merely a passive component of the region's thinned lithosphere? Is it possible that the initial phase of passive rifting could trigger more dynamic asthenospheric ascention? Where does gravitational collapse fit in?

"White Gold" of Death Valley
The story of borax is inseparable with Death Valley's human and geological history. For six years beginning in 1883, wooden wagons with a nine metric ton capacity, drawn by a team of mules led by two horses of the Harmony and Amargosa Borax Works, ferried borax out of Death Valley. The 165-mile, ten-day, whip-cracking, dusty and dangerous, arduous journey crossed the scorching salt pan, climbed over passes in the Panamint Mountains and traversed the arid Mojave Desert to the nearest railroad spur in Mojave, California. Used in detergents, ceramics, cosmetics, enamel glazes, insecticides and fire retardants, white cottonball-shaped crystals of ulexite ore mixed with mud were skimmed from the valley floor. Since 1891, the Pacific Coast Borax Company promoted the "20 Mule Team" trademark on boxes of laundry detergent and "Death Valley Days" radio and TV shows. Death Valley will likely be forever linked with the caravan as well as morbidity, foreboding and lifelessness, much to the consternation of many (especially one geologist I know). It's an unfortunate association, since the valley of death is in reality a "valley of life", perseverance, diversity and adaptation in the face of environmental extremes.

At one time, the Death Valley region was reputed to possess every mineral that put California on the map - gold, silver, copper and lead. But, it was unromantic borax - a whitish salt of boric acid - and everyday talc - a hydrated magnesium silicate - that propelled the region into prominence and led to Death Valley's long-term development. Borax, in particular, put Death Valley on the map, inspired a "white gold" rush and fostered the construction of a narrow gauge railroad, an elegant Spanish-style inn in the desert, a "castle" in a canyon, a radio and television western anthology series, a world famous National Park and a thriving tourist industry.

•  Why were the minerals of borax and talc in such commercial demand? Are they still? 
•  Where are they found? How did they form and when? 
•  What were the unique challenges associated with mining in Death Valley and getting the deposits to market? 
•  From the days of the "single-blanket jackass prospector" and the thousands of shafts and tunnels that probe the subsurface - more in Death Valley National Park than any other - what put an end to the industry that made Death Valley so famous in spite of modern techniques of exploration and mining?

Headframe of the Billie Borate Mine along the Road to Dante's View
Borax was first commercially produced in the U.S. north of San Francisco in 1864. It took almost 20 years before claims reached the arid salt pan of Death Valley in 1881. Encumbered by oppressive heat, lack of water for refining, and transportation difficulties, playa mining on the valley floor ceased when continuing exploration led to the discovery of a richer form of borate called colemanite in a larger and more concentrated lode in Furnace Creek Wash that adjoined Death Valley. Soon after, a narrow-gauge railroad was constructed to bring ore to market. Borates and other salts from the surrounding ranges that became dissolved in volcanically heated water became concentrated within long-gone Furnace Creek Lake and today resides in the lower part of the Furnace Creek Formation (behind and beneath the mine). Death Valley's mining history is punctuated with presidential and congressional closures and reopenings, but ultimately, mining ceased with the establishment of the National Park in 1994, although the underground Billie Mine is the only active operation in the park. Furnace Creek deposits on Ryan Mesa of the Greenwater Range (far left middle distance) are capped by basaltic flows of the Pliocene Funeral Formation of the southern Funeral Mountains. Across Furnace Creek Wash, the northwest-trending Furnace Creek fault zone lies before eastward-tilted sequences of the Funeral Mountains (background). Proterozoic and Paleozoic rocks were thrust-faulted and folded in late Paleozoic and Mesozoic contractional tectonism and then extended in the Cenozoic. That makes the range a transtentional horst block. The summit is Pyramid Mountain at 6,703 feet. Go there (36 20'30.20" N, 116 41'01.83" W).

The 140 mile-long, 5 to 20 mile-wide, generally north to south-trending trough is situated mostly in Inyo County in southeast California, astride the border of southwest Nevada. Its central depression reaches 282 feet below sea level and is bordered by mountains as high as 11,049 feet. The dominant orientation is north to south, but many adjacent valleys and mountain ranges trend northwest-southeast. 

In 1933, President Herbert Hoover proclaimed the region a National Monument, along with a connected triangle of land athwart the Nevada state line. In 1984, a small detached unit in Nevada was set aside as a wildlife refuge for the endangered Devil's Hole pupfish. In 1994, the region was redesignated as Death Valley National park with over 3.4 million acres (5,307 square miles). It's the largest park in the contiguous 48 states with over 95% classified as "wilderness" - rugged, unsettled, undeveloped and undivided. Go there (36°27.70 N, 116°52.00 W) to the Death Valley Visitor Center at Furnace Creek Ranch.

Death Valley National Park
Located along the southeastern border of California with southwest Nevada (inset), the park occupies the Great Basin of the Basin and Range province and the Mojave Desert and typifies the morphological, structural, climatic and biological characteristics of each. The park includes two major valleys, Panamint and Death Valley proper, separated by the Panamint Range.

In 1984, Death Valley became a UNESCO Biosphere Reserve, one of 699 internationally designated that are "reserved to protect biological and cultural diversity while promoting sustainable economic development." In 2013, the region was named an International Dark Sky Park and awarded a "Gold Tier" for the highest level of pristine nocturnal star-viewing away from urban light-pollution. The IDS in association with the National Park Service makes recommendations how dark skies can be protected such as advocating for ideal levels of outdoor light brightness, appropriate sky-shielding and hours of illumination.

Dark Skies over Racetrack Playa and its Mysterious Sailing Stones
Beneath the camera lens-bent arch of the Milky Way, the six-square mile, dry lakebed is nestled between the Cottonwood and Last Chance Ranges in the northwest corner of Death Valley. It's renowned for the locomotive mystery of its trail-leaving, "sailing stones", which has finally been solved. Mountain snowmelt that enters the playa freezes on cold winter nights along with underlying saturated silt and clay. The rocks have a higher thermal conductivity than water, which facilitates their lubrication such that even mild wind shear is able to move the thin ice sheet with its entrained rocks along parallel tracks. Once melted, the rocks are redeposited on the polygonal cracked surface of the playa. Some of the stones are sourced from the Grandstand, a granitic outcrop (center), but most of the dolomitic chunks are from the southeast. Go there (36°39.883’N, 117°33.350’W) to Racetrack Playa.
From Wikimedia Commons,, the NPS and Dan Duriscoe 

Death Valley lies within the extreme western extent of the ~800,000 sq km Basin and Range physiographic province and within the southern extent of its Great Basin subprovince. Both regions are without counterpart in North America for the extreme extension across the landscape and their average ~1,200 meter-elevation above sea level. In the late Cenozoic, crustal and lithospheric mantle thinning has occurred over an unusually wide area. 

Broad continental extension (as opposed to a narrow zone with a single downward-displaced block of crust) has given rise to the province's surface expression of alternating basins and ranges that extend over a region up to 1,000 km wide. The strain that created the extension is not uniformly distributed over the extended region. As a result, average extensions (and crustal thickness) of 50-100% can vary in areas from 100-400% and less than 10%. It is estimated that the Death Valley region, since the end of Mesozoic compressional thrust faulting, has undergone as much as 160 km of extension.

The province covers most of Nevada, portions of adjoining states and extends south into Arizona, west Texas and northwest Mexico where it engulfs the Sierra Madre Occidental Range. The province lies between the Cascade Ranges and Rockies in the north and the 600-km long granitic spine of the Sierra Nevada and Colorado Plateau in the middle and south. 

Physiographic Provinces of Southwestern North America
Death Valley (red arrow) is in southeastern California along the Nevada border. It's situated within the Mojave Desert in the rain shadow of the Sierra Nevada Range, within the Basin and Range physiographic province (dotted line) and the Great Basin subdivision.
Modified from Wikimedia Commons, image by Kmusser

Each region differs greatly in geology, age, topography, elevation, structure, hydrology, ecology, population density and human history but are related by tectonic processes that created them. Although uncertainty centers on the magnitude, style and timing of the Basin and Range formative event(s), the consensus is that it is the product of widespread, extreme extension, rather than from differential, fluvial erosional processes acting upon folded and faulted rocks in an arid climate or a compressional tectonic episode, as was once thought. It wasn't genetically linked to an extended crust until a faulting-extension connection was made. 

The province's name "basin and range" is based on geomorphology, which includes surface and sub-surface rocks, structural elements and evolutionary history. The landscape is typified by abrupt changes in elevation between rugged, longitudinal, asymmetric, tilted and fault-bound, uplifted blocks of crust that form mountain ranges called horsts (German for "heap") and broad, flat, sediment-filled, downdropped blocks of crust that form basins called grabens (German for "grave"). Death Valley typifies the province's corrugated landforms, and is its most famous, most visited and most studied region with the greatest extremes in landscape and climate.

Crustal Extension Creating Horst and Graben Features on the Landscape
From the surface, horsts and grabens appear as a series of ranges and valleys that run perpendicular to the direction of extension. The structures are caused by normal faulting where extension creates failure along a planar fracture plane. This leads to subsidence of a graben's hanging wall between two horstic foot walls. Modified from

Two kinds of extensional faults exist in the Basin and Range province: high-angle normal faults (that create the repetitive horsts and grabens and are responsible for the majority of horizontal extension) and low-angle normal detachments faults (with associated metamorphic core complexes). Both types of faults are related to the development of two superimposed stress fields in the province, one related to tectonics and the other to gravitational collapse.

Basin and Range Formation from Crustal Extension
 Normal faults (left) may not always dip in opposite directions. If dipping occurs in similar directions (center), half-grabens form and are accompanied by a domino-like tiling of the fault blocks along listric faults. Normal faults may concave upwards as the dip decreases with depth, where a deep detachment fault (right) follows a curved rather than planar path. Death Valley possesses a combination
Modified from

In the late 1880's, geologist Clarence Dutton compared the Basin and Range's alternating topography to "an army of caterpillars crawling northward out of Mexico." The extremes in elevation posed a formidable impediment to westward travel for pioneers, prospectors and settlers in the 1800's and was one of the last regions to be settled in the United States.

Caterpillars Marching Across the Basin and Range from Space
The most striking feature of the Basin and Range province is the parallelism of the mountain ranges. There are hundreds of alternating linear, towering peaks dotted with green pinyon pine and juniper, the loftiest of which are topped with snow, while intervening valleys, the basins, remain low and elongate on the landscape, monotonous, sparsely vegetated, with strangled rivers and ephemeral, salt-rich playa lakes filled with sediment from the bordering ranges. Death Valley (encircled) is in the lower left quadrant, and the elevated Colorado Plateau and Grand Canyon are in the lower right. The NASA image from space is slightly rotated counterclockwise from north.

The ~362,600 sq km Great Basin is the northern subprovince of the Basin and Range, where "The earth is splitting apart there" as well (author John McPhee). Thus, it also possesses the province's distinctive alternating landforms, but the appellation is misleading. Rather than defined by geomorphology, "great basin" is a hydrologic definition. Precipitation is not directed centrally into a massive catchment as implied but into range-flanked, below sea level, endorheic (Greek for "flow within") basins, over 200. 

Each range-basin-range triplet is a closed-system, whose waters, scant and variable as they may be, have no outlet to the sea. Each range  acts as a hydrologic drainage divide that runs down its axis. Water is directed from the ranges' relatively impermeable bedrock to broad basins where over 90% is lost due to evaporation and the rest enters playa or forms aquifers, dictated by regional structure and lithology. Aquifers are the principal source of ground water in over 120 alluvium-filled basins. Draped over this framework are erosionally-created features such as wine-glass canyons, triangular-shaped facets, spur benches, regularly-spaced catchments and omnipresent alluvial fans. Death Valley is representative of the province's geomorphology and the subprovince's hydrology.

Schematic of Types of Hydrologic Areas of Nevada's Great Basin
The Great Basin is a physiographic province based on hydrology, where all combinations of open, closed, undrained, partly drained, and completely drained hydrologic areas are found. Areas underlain and bounded by impermeable bedrock generally are undrained with no subsurface inflow or outflow, the water table beneath the valley floor is near the surface. In a completely drained area, the water table beneath the valley floor may be so deep that all ground-water discharge is by subsurface outflow.
From Maurer et al, 2004.

The Great Basin is a temperate or "cold" desert with hot and dry summers and snowy winters. Aridity is created by the massive rainshadow of the Sierra Nevada Range to the west in addition to local ranges that border each basin. Deserts are defined not by the presence of sand, which to the surprise of first time visitors comprises less than 10% of Death Valley, but by annual precipitation, which is generally less than ten inches. The Great Basin averages nine on the west side and 12 on the east. Before reaching the Great Basin, prevailing westerlies must cross the high Sierra Nevada and local ranges that border the basins such as the Panamints on Death Valley's west side where annual rainfall averages an incredible 2.36 inches!

The Rainshadow Effect
Forced upward against the Sierra Nevada by orographic lift, rising Pacific Ocean moisture-laden air adabiatically cools and generates precipitation on the windward side of the range. Dry air descends producing a vast rainshadow within the desert of the Great Basin on the leeward side. On the west of the range, rivers flow to the sea, while on the leeward side, waters of the Great Basin never reach it. Death Valley is one of the Great Basin's most extreme examples of aridity.
From Wikipedia Creative  Commons

As warm, moisture-laden air rises on the windward side of the mountains, it expands and loses heat and moisture in a process called adiabatic cooling. Descending drier air contracts on the leeward side and warms as its humidity plummets. In Death Valley's Badwater Basin, which reaches 282 feet below sea level, high pressure and dry conditions dominate due to the greater weight of the atmosphere above. By the time it reaches Death Valley's sunken floor, the super-heated air is dry as a bone.

Salt Pan of Devil's Golf Course against a Backdrop of Telescope Peak
What a contrast of extremes - snow on the summit of 11,049 foot Telescope Peak and the arid salt pan of Badwater Basin at 282 feet below sea level - separated by over two miles of relief! Devil's Golf Course at Badwater's northern end is a field of jagged pinnacles of silty halite fed by capillary action. Its name was acquired from a 1934 National Park Service guidebook that stated "Only the devil could play golf" there. The mix of hardened mud and halite evaporites is derived from the physical and chemical erosion of the surrounding mountains. Sloping away from the Panamint Mountains is a bajada, formed from coalesced alluvial fans, whose massivity is related to the size of the range and downward slope of the valley floor. Typical of arid sedimentary basins, the fans are signature Quaternary features of Death Valley. Go there (36°17.150’N, 116°49.574’W) to the Devil's Golf Course.

Snowmelt, mountain runoff, springs and water seeps along the fronts and negligible rain within the basins either accumulates in ephemeral, hypersaline playa lakes, infrequently makes its way to adjoining basins, enters the subsurface recharging aquifers or most likely evapotranspirates into the atmosphere in the intense heat. Although scarce, when rain does occur, it can have a catastrophic effect on the landscape by breaking down rock and transporting it down mountain. Alluvial fans, extensive bajadas, debris flows and thousands of feet of sediment basin-fill are commonplace. In Utah, the Great Salt Lake is the Great Basin's largest internal "drain", while Death Valley is arguably its most famous and most studied landform with classic basin and range topography and with an internal hydrologic basin that covers some 8,700 square miles.

Blue-Green Pools and Frozen Rivers of Salt
A serpentine stream has made its way to a short-lived, saltwater-rich, playa lake nestled in a small hollow of Badwater Basin in central Death Valley. The salt pan, one of the planet's largest, is a hot and dry desert of chemical salts (light-colored) and mud (dark-colored) baking in the sun. In addition to springs and mountain runoff, it receives the terminal reach of the intermittent Amargosa River from the south and equally-ephemeral, spring-fed Salt Creek from the north. Eventually, all water succumbs to the heat. Many scattered pools are remnants of heavy rains from late 2015. So heavy was the deluge that dry washes in the north were transformed into floodwaters 100 feet wide with 20-foot waves that left mud, rock debris and damaged roads in Grapevine Canyon. Still reeling from flash floods, Scotty's Castle will be closed for a year or more. Go there (36°11'30.02" N, 116°46'34.57" W) to Badwater Basin.

Death Valley lies within the northern arm of the Mojave Desert, North America's smallest, driest, most unspoiled and undivided North American desert with the greatest range of elevations. The Mojave is a rainshadow desert and serves as a transition zone between the hot Sonoran Desert to the south and cooler Great Basin Desert to the north. The Joshua Tree is considered the region's indicator species and occurs at elevations between 1,300 and 5,900 feet and defines the areal limits of Mojave's ecosystem.

Joshua Tree in the Ghost Town of Rhyolite in the Bullfrog Hills
A Joshua Tree with its dagger-like spines in the Bullfrog Hills of Amargosa Valley stands as a lone sentinel in the ghost town of Rhyolite. The cactus, a member of the Yucca genus and member of the Agave family, reminded Mormon settlers who crossed the desert in the mid-1800's of Biblical Joshua reaching his hands to the sky in prayer. Amargosa is the valley to the east of Death Valley and is separated from it by the Grapevine Mountains of the northern Amargosa Range (far left). Bullfrog acquired its name from the land claims of Frank "Shorty" Harris and Ernest L. Cross, legendary prospectors who discovered gold in 1904. Go there (36°53'59.12" N, 116°49'43.61" W) to Rhyolite.

In addition to occupying a locale within the Basin and Range and Great Basin, Death Valley is transitional between three partly overlapping seismic provinces - the Basin and Range, the Walker Lane Belt and the Eastern California Shear Zone. All three are actively deforming regions of extension and shear. Although some combine the latter two into a continuous zone, they are evolving components of the San Andreas fault system along the coast of California. 

The arrival of the East Pacific Rise spreading center at the Farallon-North American plate subduction zone initiated extension about 27 million years ago and 17-18 million years ago at Death Valley. What is the relationship of Death Valley to the San Andreas system, and how did it come to form? Please visit post Part II for an explanation.

Southwest Regional Structure Map of Southeastern California
Shown are the Basin and Range extensional province, the Walker Lane belt and Eastern California seismic zones, the Garlock Fault (a left-lateral strike-slip fault along the north margin of the Mohave Desert), the San Andreas fault system and the Death Valley domain. Death Valley is juxtaposed between a southern extension of the Walker Lane belt on the north and the Garlock fault on the south.
From Ian Norton, 2011.

The Mohave Desert is also a structurally transitional region, in that it contains the Mohave block. The block is a wedge-shaped zone with clockwise rotation between the dextral San Andreas fault on the west and the sinistral strike-slip Garlock fault in the north. The Garlock separates the Mojave region from the Basin and Range province to the north and connects with the dextral Southern Death Valley fault zone. The entire region - the Basin and Range province, the Mojave block and Death Valley region prior to the Oligocene - was a tectonically quiescent, lithospherically unextended, externally-drained plateau. These aspects were reversed when the Farallon-North-American plate subduction zone encountered the Farallon-Pacific spreading ridge. Please visit post Part II for more info.

Death Valley acquired its infamous moniker in 1849 when a member of "The Lost '49ers" - a group of pioneers and prospectors who made an ill-fated attempt to find a 500-mile short-cut to the California goldfields - looked back one last time and exclaimed, "Goodbye, Death Valley." The name stuck (to the dismay of at least one geologist I know). But don't be's a complete misnomer. Death Valley isn't a valley, and it's far from dead - either biologically or geologically.

"Leaving Death Valley - The Manly Party on the March After Leaving Their Wagons"
Making the arduous journey on foot after butchering their starving oxen for jerky, the Bennett and Arcane families crossed Death Valley's barren desert and lofty Panamint Mountains to the west. Only one of the emigrants died within the valley itself, but the hardships and agony the group encountered were immense and legendary. The ordeal is recounted in William Manly's autobiography. "A man in a starving condition is a savage. He may be as blood-shed and selfish as a wild beast, as docile and gentle as a lamb, or as wild and crazy as a terrified animal, devoid of affection, reason or thought of justice." Manly and partner John Rogers left the destitute group and returned from California to rescue them with provisions. Manly's account did much to popularize Death Valley to the American public. Manly Beacon, Lake Manly and Manly Pass are tributes to his humanitarianism and heroism.
Illustration from Chapter X of William L. Manly's autobiography Death Valley in '49

Geologically speaking, Death Valley is a basin not a valley. Valleys might look similar - regions of low relief and sediment-filled between topographic highs - but their genesis is erosional, produced by the carving action of rivers or gouging of glaciers. Basins - whether bowl-shaped or elongate and often below sea level - sport a tectonic origin. They can be very small (hundreds of meters) or very large (such as ocean basins), but the essential element is the prolonged tectonic creation of relief. 

In Death Valley, extension has bestowed the basin with faults along its flanks, a flat or tilted, down-dropping floor that provides accommodation space for the deposition of thick sediment and parallel mountain ranges along the sides of the basin. The mountain ranges are more steeply sloped on their western flanks in contrast to the eastern flanks, which drops less precipitously to the neighboring basins. The architecture is perhaps visualized best on an elevation profile generated along a 77 km-long SW-NE geologic transect (red line) across the landscape of Death Valley through the ranges and basins that flank it.

Death Valley Transect and Elevation Profile
The SW-NE transect (red line) runs from the basins of Panamint Valley to Amargosa Valley and across Death Valley. The profile illustrates the characteristically steep western slope of the ranges. Subtle listric eastward tilt of the valley floor is disguised by voluminous sediment derived from the ranges but is betrayed by the magnitude of the alluvial complex on the valley's western side. Furnace Creek Wash is an elevated pre-Death Valley basin. Even with a vertical exaggeration of 1X, the dramatic height of Telescope Peak above the floor of Death Valley and the Black Mountains is evident. Note the higher elevation of Furnace Creek Wash, the steepness of Black Mountains' western front and the dimensions of the bajada on the west side of the valley.
Transect and profile generated on Google Earth. Click image for a larger view.

As for the absence of life, Death Valley's Badwater Basin with the Western Hemisphere's lowest elevation, maximum temperatures and near greatest aridity is indeed desolate, salt-infused and lifeless (with the exception of ancient, halo-tolerant prokaryotic Archaea micro-organisms recently discovered). Factor in scorching summers and freezing winters. Everything changes with elevation with increasing water exposure as temperatures become cooler and more life-tolerant. In Death Valley, life is defined and confined by the availability of water.

A Miracle of Germination
Enticed to germinate during the 2016 wildflower "superbloom", this purple, five-lobed, notch-leafed Phacelia (Phacelia crenulata) blossomed on a gravelly, spring-fed slope of an alluvial fan. It's a foul-smelling plant that produces a contact rash similar to that of poison ivy. Desert plants, as do animals, use physical and behavioral mechanisms to adapt to the extremes of heat and aridity. Xerophytes, such as cacti, store and conserve water, often with few or no leaves to reduce transpirational water loss. Phreatophytes adapt by growing long roots to acquire moisture at or near the water table, or shallow roots spread over a large area. Behavioral adaptations include lifestyles in conformance with the seasons of greatest moisture and/or coolest temperatures. Perennials survive by remaining dormant until water is available; whereas, annuals, such as Phacelia, live for a single season when seeds are stimulated to germinate by moisture. Growing, flowering and seeding quickly, they die. As temperatures rose with the approach of summer, flowers retreated to higher and cooler elevations.

Death Valley's lifeforms are specially adapted to cope with the region's extremes. Life and diversity appear within the Lower Sonoran ecosystem in the first 4,000 feet, where a host of specially evolved lifeforms have adapted to environmental extremes. Cacti, desert holly, scorpions, sidewinders, ravens, roadrunners, kit foxes and kangaroo rats thrive. From 4,000 to 8,500 feet, Upper Sonoran pinyon pine and juniper, and small mammals and reptiles persist. From 4,000 to 8,500 feet within the Transition Zone, sierra juniper, mountain mahogany, mule deer, bobcats, cougars and coyotes exist, and up to 9,000 feet in the Sub-Alpine Zone, where bristlecone pine, limber and bighorn sheep are found. These lifeforms defy our conventional images of Death Valley. Each has evolved creative solutions to the problems of survival.

Late Cenozoic extensional forces wreaked havoc on the landscape of Death Valley. They uplfited, tilted, deformed, stretched and wrenched crustal blocks of Proterozoic through Cenozoic strata into elongate mountain ranges, while downdropping intervening blocks within basins that variably filled with range-derived colluvium and alluvium, long-gone Pleistocene lakes and saliferous playa. 

The basins contain the deposits that put the region on the map, while the ranges contain the region's oldest rocks and tell the story of Death Valley's ancient past. An excursion would be incomplete without a visit to both. In my next post, I'll present a condensed synopsis of Death Valley's geologic evolution that spans nearly two billion years. Thank you for visiting!

Immense gratitude is offered to geologist and author Wayne Ranney for his knowledge, expertise, unlimited enthusiasm, endless wit, exceptional car-camping cuisine, friendship and great companionship. Please visit Wayne here. Great appreciation is also extended to Marli Miller for her personal communications, thoughtful explanations and photographic contributions. A stop at Bennie Troxel's Museum Rock Trail in nearby Shoshone, California is highly recommended. His outdoor chronologic collection of large rocks tells the geologic story of the Death Valley region. And of course, there's Death Valley National Park. Go there!

Thanks, Wayne, for another great trip and for taking me to the next level!

•  Ancient Landscapes of the Colorado Plateau by Ron Blakey and Wayne Ranney, 2008.
•  A Trip Through Death Valley's Geologic Past by Kenneth E. Lengner, 2009.
•  Death Valley's Titus Canyon and Leadfield Ghost Town by Ken Lengner and Bennie Troxel, Second Edition, 2008.
•  Geology of the American Southwest by W. Scott Baldridge, 2004.
•  Geology of Death Valley National Park by Marli B. Miller and Lauren A. Wright, Third Edition, 2015.
•  Geology of the Great Basin by Bill Fiero, 1986.
•  Geology Underfoot in Death Valley and Owens Valley by Robert P. Sharp and Allen F. Glazner, 2012.
•  Geology Underfoot in Southern California by Robert P. Sharp and Allen F. Glazner, 2014.
•  Hiking Death Valley by Michel Digonnet, 1972.
•  Images of America - Death Valley by Robert P. Palazzo, 2008.
•  Plate Tectonics by Wolfgang Frisch et al, 2011.

•  Geologic Map of the Death Valley Ground-Water Model Area, Nevada and California by J.B. Workman et al, 2002.
•  Death Valley National Park Map here

•  A Trip Through Death Valley's Geologic Past by Kenneth E. Lengner, 2009.
•  Cal Poly Geology Club, Death Valley Field Trip – 2004 (On-line)
•  Death Valley National Park Visitor Guide - Winter/Spring 2016 
•  Death Valley's Titus Canyon and Leadfield Ghost Town by Ken Lengner and Bennie Troxel, Second Edition, 2008.
•  Field Trip Guide to Death Valley National Park, Geology of the National Parks, San Francisco State University, March 22-26, 2002 (On-line)
•  Geology of Death Valley National Park by Marli B. Miller and Lauren A. Wright, Third Edition, 2015
•  Hiking Death Valley by Michel Digonnet, 1972.
•  Hofstra University, Field Trip Guidebook, Geology 143D - Geology of California/Nevada, Spring Semester April 11, 2009 (On-line)
•  Proceedings of Conference on Status of Geologic Research and Mapping in Death Valley National Park, Las Vegas, Nevada, USGS, Open File Report 99-153, 1999 (On-Line)
•  Quaternary and Late Pliocene Geology of the Death Valley Region: Recent Observations on Tectonics, Stratigraphy, and Lake Cycles, Guidebook for the 2001 Pacific Cell—Friends of the Pleistocene Fieldtrip (Online)
•  Stanford Project on Deep-Water Depositional Systems, 23rd Annual Meeting and Field Workshop, Death Valley California, Field Guide: Upper Paleozoic Deep-Water Passive Margin Sequences of the Death Valley Region (On-line)
•  Virtual Field Guide of the Death Valley Region, Geology Program, Department of Earth Sciences, Palomar College (On-line)

•  Analogue Modelling of Continental Extension: A Review Focused on the Relations Between the Patterns of Deformation and the Presence of Magma by Giacomo Corti et al, Earth-Science Reviews 63, 2003.
•  An Imbricate Midcrustal Suture Zone: The Mojave-Yavapai Province Boundary in Grand Canyon, Arizona by Mark E. Holland et al, GSA Bulletin, September/October 2015.
•  A Positive Test of East Antarctica–Laurentia Juxtaposition Within the Rodinia Supercontinent by J. W. Goodge et al, Science, 2008. 
Assembly, Configuration, and Break-up History of Rodinia: A Synthesis by Z.X. Li et al, Precambrian Research, 2008.
•  A USGS Study of Talc Deposits and Associated Amphibole Asbestos Within Mined Deposits of the Southern Death Valley Region, California by Bradley S. Van Gosen et al, USGS, 2004. 
•  Basin and Range Volcanism as a Passive Response to Extensional Tectonics by Keith Putirka and Bryant Platt, Geosphere, 2012.
•  Cenozoic Extension and Magmatism in the North American Cordillera: The Role of Gravitational Collapse by Mian Liu, Tectonophysics 342, 2001.
•  Detrital Zircon Provence, Geochronology and Revised Stratigraphy of the Mesoproterozoic and Neoproterozoic Pahrump (Super) Group, Death Valley Region, California by Robert Clyde Mahon, Thesis, Idaho State University, 2012.
•  Evolution of Mountainous Topography in the Basin and Range Province by Michael A. Ellis et al, Basin Research, 1999. 
•  Extensional Tectonics in the Basin and Range Province and the Geology of the Grapevine Mountains, Death Valley Region, California and Nevada, Thesis by Nathan A. Niemi, CIT, 2002.
•  Geochronologic and Stratigraphic Constraints on the Mesoproterozoic and Neoproterozoic Pahrump Group, Death Valley, California: A Record of the Assembly, Stability, and Breakup of Rodinia by Robert C. Mahon et al, GSA Bulletin, 2014.
•  Geologic map of the Death Valley Ground-Water Model Area, Nevada and California by J.B. Workman et al, USGS 2381-A, 2002.
•  Geomorphic Evidence for Late-Wisconsin and Holocene Tectonic Deformation, Death Valley, California by Roger L. Hooke, GSA Bulletin, 1972.
•  Glacigenic and Related Strata of the Neoproterozoic Kingston Peak Formation in the Panamint Range, Death Valley Region, California, etc. by Ryan Peterson, Thesis, CIT, 2009. 
•  Gravitational collapse of the continental crust: definition, regimes and modes by P. Reya et al, Tectonophysics 342, 2001.
•  Groundwater Geology and Hydrology of Death Valley National Park, California and Nevada by M.S. Bedinger and J.R.Harrill, Technical Report NPS/NRSS/WRD/NRTR—2012/652, 2012.
•  Hydrogeology and Hydrologic Landscape Regions of Nevada by Douglas K. Maurer et al, USGS Report 2004-5131, 2004. 
•  Late Cenozoic Crustal Extension and Magmatism, Southern Death Valley Region, California by J.P. Calzia and O.T. Ramo, GSA Field Guide 2, 2000.
•  Late Quaternary Tectonic Activity on the Death Valley and Furnace Creek Faults, Death Valley, California by Ralph E. Klinger and Lucille A. Piety, USGA, 2001.
•  Nd Isotopic Composition of Cratonic Rocks in the Southern Death Valley Region: Evidence for a Substantial Archean Source Component in Mojavia by O.T. Remo and J.P. Calzia, Geology 26, 1998. 
•  Neoproterozoic Uinta Mountain Group of Northeastern Utah: Pre-Sturtian Geographic, Tectonic and Biologic Evolution by Carol M. Dehler et al, GSA Field Guide 6, 2005.
• Sliding Stones of Racetrack Playa, Death Valley, USA: The Roles of Rock Thermal Conductivity and Fluctuating Water Levels by Gunther Kletetschka et al, Geomorphology, 2013.
Supercontinent Tectonics and Biogeochemical Cycle: A Matter of ‘Life and Death’ by M. Santosh, Geoscience Frontiers, 2010. 
• Tectonic influences on the spatial and temporal evolution of the Walker Lane by James E. Faulds and Christopher D. Henry, Arizona Geological Society, Digest 22, 2008.
Tectonic Model for the Proterozoic Growth of North America by Steven J. Whitmeyer and Karl E. Karlstrom, Geosphere, 2007. 
•  Tectonostratigraphic Evolution of the ~780–730 Ma Beck Spring Dolomite: Basin Formation in the Core of Rodinia by Emily F. Smith et al, Geological Society of London, 2015. 
•  Terrestrial Cosmogenic-Nuclide Dating of Alluvial Fans in Death Valley, California by Michael N. Machette et al, USGS, Professional Paper 1755, 2008. 
•  The Laurentian Record of Neoproterozoic Glaciation, Tectonism, and Eukaryotic Evolution in Death Valley, California by Francis A. Macdonald et al, GSA Bulletin, 2013.
•  The Making and Unmaking of a Supercontinent: Rodinia Revisited Joseph G. Meert and Trond H. Torsvik, Tectonophysics, 375, 2003. 
•  The Relationship between the Neoproterozoic Noonday Dolomite and the Ibex Formation: New Observations and Their Bearing on "Snowball Earth" by Frank A. Corsetti and Alan J. Kaufman, Earth Science Reviews, 2005. 
•  Toward a Neoproterozoic Composite Carbon-isotope Record by Galven P. Halverson et al, GSA Bulletin, 2005.
•  Two Diamictites, Two Cap Carbonates, Two Carbon 13 Excursions, Two Rifts: The Neoproterozoic Kingston Peak Formation, Death Valley, California by A.R. Prave, Geology, 1999.
•  Two-stage Formation of Death Valley by Ian Norton, GSA Geosphere, 2011.
•  U-Pb Geochronology of 1.1 Ga Diabase in the Southwestern United States: Testing Models for the Origin of a Post-Grenville Large Igneous Province by Ryan M. Bright et al, Lithosphere online, 2014.
•  Variations Across and Along a Major Continental Rift: an Interdisciplinary Study of the Basin and Range Province, Western USA by Craig H. Jones et al, Tectonophysics 213, 1992.