Powell Point at the Top of the Grand Staircase

KODAKCHROME BASIN
Traveling north on the unpaved Cottonwood Canyon Road in south-central Utah, this overlook oversees the appropriately-named Kodachrome Basin State Park. A National Geographic expedition "Motoring into Escalante Land" first penned the colorful park name in a September 1949 article. Initially, Kodak objected to the magazine's usage of the product name of the film, still in its infancy, without permission, but later recanted after recognizing the obvious marketing value.

Notice the tilted sedimentary beds. Widely-spaced faults and monoclines punctuate the region. The flat-topped summit on the horizon is Powell Point, our destination, about 12 miles as the crow flies.

View looking north from Slick Rock Bench (near Wiggler Wash) at the Kodachrome Basin. Powell Point (center) is atop the Table Cliffs Plateau to the left of the gap on the horizon, while Canaan Peak is off to the right. Note the steeply dipping rocks (Entrada through Straight Cliffs Formation) that form the tail of a monocline between a branch of the Kaibab anticline and the Hackberry Canyon syncline.

THE SAN RAFAEL GROUP
The "picture perfect" vista is brought to you courtesy of the geological San Rafael Group. The multi-member, stratal package formed when a finger-like incursion of the former Panthalassic Ocean and the now-named Pacific Ocean invaded the land from the north and extended into the shallow Utah-Idaho trough during the Middle Jurassic. The depression of the trough was induced subsequent to the formation of an orogenic belt from the west in Nevada. The tectonic event was the Nevadan orogeny, the first of three major mountain-building episodes that completely transformed western North America during the Mesozoic. The mountain belt and its foreland basin are clearly visible on the Middle Jurassic paleo-map below.

The elongate marine embayment, also referred to as the Sundance seaway, deposited alternating sequences of terrestrial and shallow marine deposits. Depending on where you're travelling in the southeast quarter of Utah and western Colorado, you'll see the San Rafael's red and brown mudstones and and shales interjected with light-colored beds of evaporites and eolian sandstones of the Page and Entrada Sandstones, and the Carmel, Curtis and Summerville Formations.

Middle Jurassic Paleography of Western North America
Ron Blakey, Colorado Plateau Geosystems, Inc.

THE PINK CLIFFS OF THE GRAND STAIRCASE
The following spectacular western scene is encountered further north along the Cottonwood Road. We're barely three miles from Cannonville, Utah, situated on Scenic Byway 12. The San Rafael Group's various layers are illuminating the landscape. Drawing ever near, Powell Point anoints the summit of the Grand Staircase's Pink Cliffs at 10,188 feet.

Envision the Grand Staircase as a multi-stepped, geological layercake that begins above the North Rim of the Grand Canyon in Arizona to the south and extends 150 miles to the north into southern Utah. It's subdivided into 6,000 vertical feet of cliffs, the risers of the stairs that are named by color, and intervening terraces or benches. The alternating cliff/slope and bench/terrace configuration is related to varied erosion rates of the various rock types. The cliffs are comprised of harder rocks that are more resistant to erosion (such as sandstone and limestone); whereas, the benches possess softer rocks that erode more readily (with shale and siltstone). 

Modified from nature.nps.gov

The Grand Staircase is the westernmost member of the 1.9 million-acre Grand Staircase-Escalante National Monument, created by President Bill Clinton in 1996. The other two geographical sections are the Kaiparowits Basin and, furthest east, Escalante Canyons.

SKUTUMPAH TERRACE
Powell Point is the highest point on the geological cake, the icing if you will, residing on top of the Pink Cliffs. Below it is a bench, then a step, then another bench, and so on. This photo was taken from the Skutumpah Terrace, below the second riser of the Staircase called the Gray Cliffs to the north, somewhat hidden in the photo. The riser below us, to the south, is the White Cliffs of glistening Navajo Sandstone. The colorful terrace is built on softer, more erodible deposits of the Carmel and the overlying Entrada Sandstone, both related to the advance of the aforementioned seaway.  


THE CLARON FORMATION
Powell Point, seen from atop the Skutumpah Road just to the west of Kodachrome Basin, was named in 1879 by the geologist Clarence Dutton in honor of his famous contemporary colleague John Wesley Powell, the iconic geologist and explorer of the American West. The Point is held up by the white and pink limey cliffs of the Claron Formation, deposited during the Eocene around 55 million years ago in a vast system of freshwater shallow lakes and streams. The lower pink stratum is colored by oxides of the mineral hematite. They are the same formations that have eroded into the ghostly spires, badlands and hoodoos of Bryce Canyon and Cedar Breaks just to the west.

Middle Jurassic Paleography of Western North America
Ron Blakey, Colorado Plateau Geosystems, Inc.

Intertonguing Carmel Formation and Page Sandstone deposits of the San Rafael Group occupy the foreground that became interbedded as the sea level of the Sundance sea transgressed and regressed on land. And in the middle distance, gray badlands and slopes of the Gray Cliffs luxuriate below the high plateau of Powell Point, our next stop.

Powell Point is atop the white and pink Pink Cliffs seen from the Skutumpah Road
that traverses multi-colored strata of the San Rafael Group.
The various benches, slopes and cliffs of the Gray Cliffs are below.

POWELL POINT OF THE TABLE CLIFFS PLATEAU
We've arrived near the top of the Grand Staircase! Powell Point is about four miles to the west of paved Highway 12, where this photo was taken. At one time, like the other concordant high plateaus (consisting of the same strata) of the region, Table Cliffs Plateau was capped by resistant basalt during the Oligocene, which served to protect the underlying Claron Formation from erosion.

The Claron, being weakly-lithified (less rigid and erosion-susceptible), assaulted by frequent freeze-thaw cycles at this lofty elevation, and winnowed away by headward erosion of the Paria River system, has caused Powell Point to retreat as its cliffs are inexorably excavated away. On a grander scale, the Table Cliffs Plateau is situated on the east, high-side of the Paunsaugant fault, a Basin and Range extensional feature that threatens the demise of the other high plateaus, and possibly (likely) the entire Colorado Plateau. It’s only a matter of time.

CRETACEOUS GRAY CLIFFS
The vegetated slopes directly below the Table Cliffs Plateau consist of the Pine Hollow and Canaan Peak Formations deposited in the Paleocene of the Cenozoic Era by streams and rivers. Together, they straddle the boundary between the latest Mesozoic's Cretaceous Period and the earliest Cenozoic, the deposits of which hold up Powell Point. Immediately below, the Cretaceous blue-gray badlands are eroding into the base of the Pink Cliffs.

The Cretaceous Period was a time of tectonic activity, elevated sea level and climate change in western North America. It is estimated that one-third of the world's landmass at the time was submerged during this unprecedented rise in sea level. The units of the Cretaceous record the marine filling of an immense foreland basin that formed as the Sevier orogeny deformed the continent's interior. The Sevier was the second Mesozoic orogeny to transform western North America.

Sevier-induced deformation of the continent’s western interior (related to compression on North America's western margin) and high global eustasy (elevated sea level related to the formation of new oceanic crust) acted in concert to drown the craton (continental interior) in a vast, north-south inland sea that reached from the Arctic to the Gulf of Mexico, and divided the newly-formed North American continent in two. The vertical and horizontal oscillations of this Western Interior seaway blanketed its bottom with mud, while its shoreline was marked with swamps fed by sediments from east-flowing rivers that originated from mountains of the Sevier orogenic belt to the west. That explains why you can find sea shells in Kansas, sharks teeth in South Dakota and beach sands throughout the Great Plains.

Late Cretaceous Paleography of Western North America
Ron Blakey, Colorado Plateau Geosystems, Inc.

THE BIRTH OF THE BLUES
“The Blues” situated below the white and pink Claron cliffs of Powell Point, consist of drab, blue-gray fluvial and floodplain sequences of the highly fossiliferous Kaiparowits Formation. The descending strata include the Wahweap, Straight Cliffs, Tropic Shale and Dakota Formations. The Staircase's Gray Cliffs are a series of low cliffs formed from hard sandstones with several intervening benches of softer sandstones and shales. These deposits formed during the great epeirogenic (continental) flood of the Western Interior Seaway, biblical in proportions but not in origin. Amen.

THE GEOLOGICAL BIG PICTURE
The following diagram of the Grand Staircase illustrates the direction we travelled north from the Skutumpah Terrace to Powell Point atop the Pink Cliffs. As we gained altitude and crossed from each successive bench and riser, we also rose stratigraphically into deposits that were laid down earlier, from the Mesozoic through the Cenozoic.

At its maximum development at about 90 million years ago, the continental sea inundated two-thirds of the eastern portions of Utah and Arizona. The sea's two-major transgressions and regressions (advances and retreats) left a stratigraphic record of largely sandstones and shales that blanketed the landscape, covering the entire Grand Staircase. Its deposits, originally at sea level, now reside at an elevation of two miles!

Stated another way, if standing on Powell Point today looking south down the Grand Staircase in the direction of the Grand Canyon, the lower benches and risers of the White, Vermilion and Chocolate Cliffs have lost their overlying Cretaceous strata from erosion, referred to by geologists as "unroofing." This is a consequence of the uplift of the entire Colorado Plateau on which the Grand Staircase is a part. 

During the Late Cretaceous, the Colorado Plateau is thought to have initiated a "gentle" bouyant ascent due to the Laramide orogeny, the third mountain-building event to transform western North America. Rather than creating a range of mountains, as it did with the Rockies, the Laramide created the Colorado Plateau, a largely un-deformed and yet two-mile uplifted-block of continental crust. That event carried sediments formed at sea level to the various cliffs and benches of the Grand Staircase. With all that we know, the timing and precise mechanism of this and subsequent uplift has remained a major enigma in geology for almost 150 years.

Modified from Geologic Road Guides to Grand Staircase-Escalante National Monument, Utah,
Utah Geological Association Publication 29

Our ascent of the upper portion of the Grand Staircase has taken us from the Middle Jurassic period of the Mesozoic (about 170 million years ago) through the Eocene epoch of the early Cenozoic (about 55 million years ago). Within that time frame, a Middle Jurassic seaway invaded the region from the west and deposited the sediments of the San Rafael Group, seen on the Skutumpah Terrace. Tectonic collisions along North America's west coast beginning in the latest Jurassic formed the Western Interior seaway, whose Late Cretaceous sediments are seen within the Gray Cliffs. And during the Eocene, pink and gray limey deposits of the Claron Formation were deposited within a system of freshwater streams and lakes, seen in the Pink Cliffs.

Memorable Places Here and There on the Colorado Plateau: The “Wide, Open Spaces” of Escalante

For me, there’s nothing like “the wide, open spaces.” Perhaps it comes from growing up in Central New York State. The landscape there is quite striking, but the horizon is usually only as far as the next glacial drumlin.

This expansive vista looks down the long escarpment of the Straight Cliffs, the cliff-face of Fiftymile Mountain in central-south Utah. Follow the cliffs to the horizon through the rugged, wash-punctuated, desert benchland, and you end up at a spectacular drop-off at Lake Powell, the man-made reservoir created by the flooding of Glen Canyon

by the controversial Glen Canyon Dam. That’s exactly the route that the early pioneers of the Church of the Latter Day Saints, better known as Mormons, followed in 1878 called the Hole-in-the-Rock Road.

Their mission was to establish a new settlement in the region of the San Juan River in southeastern Utah. They did so by forging a road through the desert from Escalante, negotiating the sheer cliff at the Hole-in-the-Rock and crossing the untamed Colorado River with 234 men, women and children, 83 wagons, livestock and all their worldly possessions. Their epic “shortcut” was only used for one year before being abandoned. We drove on the Hole-in-the-Rock Road, the contemporary version, that essentially parallels their trail through the region of the Escalante Canyons.

GETTING OUR BEARINGS
The Straight Cliffs rise 1,110 feet or more, and as their name implies, extend for 50 miles to the southeast. The cliffs form the eastern escarpment of Fiftymile Mountain called “mountain lying down” by Native American Paiutes and the “Fifty” by local Mormons. Its rock face is a long, nearly continuous wall from the town of Escalante, Utah, southward to the Colorado River. Largely free from side canyons or protruding spurs, only two canyons throughout its length break its otherwise straight line of cliffs, greened with clumps of juniper, sagebrush and piñon.

At the foot of the cliffs runs Fiftymile Bench, a platform or broad terrace with a line of smaller, lower cliffs of its own, and more well-developed in the southern reaches of the Straight Cliffs. At various intervals, a succession of cusps juts out from the long bench.

And below the bench, lies the sagebrush, blackbrush, rabbitbrush and cacti decorated desert through which we traveled. The area is remote, isolated and majestically beautiful.

A GEOLOGICAL BOUNDARY
The Straight Cliffs and Fiftymile Mountain form the geological boundary between two of three sections of the 1.9 million acre Grand Staircase-Escalante National Monument (GSENM), the central Kaiparowits Basin section, and the easternmost Escalante Canyons section. The desert to the east of the Straight Cliffs, on which we traveled, marks the beginning of the Escalante Canyons region. It includes the winding Escalante River and the canyons it has dissected largely through the Glen Canyon Group’s sandstones.

The uppermost diagram (below) shows the centrally-located, dissected-mesa of the Kaiparowits section of the GSENM, viewed from a northern perspective. Fiftymile Mountain and the Straight Cliffs (circled) form the natural boundary with the easternmost section of the monument, Escalante Canyons (lowermost diagram). The Escalante Canyons section is viewed from a southern perspective.   

THE STRAIGHT CLIFFS ARE GRAY CLIFFS
The Straight Cliffs are one of the boldest expressions of the Gray Cliffs of the Grand Staircase, the GSENM's westernmost section. The Staircase is a series of topographic benches and cliffs, and that, as its name implies,  progressively steps up in elevation from south to north, from northern Arizona into southern Utah. The Straight Cliffs lies to the east and well outside the Grand Staircase section but are composed of the same durable Cretaceous sandstones that form the second highest riser of the Grand Staircase’s Gray Cliffs.

THE REGIONAL GEOLOGY IS A REFLECTION OF THE TECTONIC BIG PICTURE
The relentless drought of the Early Jurassic that dominated the vicinity of the future Colorado Plateau  brought the Wingate and Navajo wind-driven sand seas of the Glen Canyon Group to the region. Likewise in the Middle Jurassic, the Page and Entrada Sandstone eolian ergs inundated the region, but this time in association with the Sundance Sea, a narrow restricted arm of the ocean that entered from Wyoming into the subsidence space of the Utah-Idaho Trough, a foreland basin. The complex and varied deposits of the sea's fluctuating shoreline left the sediments of the San Rafael Group (such as the region's Carmel, Page and Entrada silt and sandstones).

During the Late Jurassic the region experienced the widespread, fluvially-generated Morrison Formation in the wake of the Nevadan Orogeny to the west, a mountain-building event that contributed to the formation of the Cordilleran Arc. Cordilleran Orogenesis in the western United States spanned at least 120 million years from the Middle Jurassic into early Eocene time. It comprised numerous mountain-building events that culminated with the formation of an enormous, elongate mountain range from Alaska to southern Mexico, with a complex and diverse stratigraphy.

Beginning in the latest Jurassic, the subduction of the oceanic Farallon Plate beneath the North American Plate along western North America resulted in the formation of the Sevier fold and thrust belt. Siliciclastic sediments were shed from the west carried by rivers into a seaway that formed in the immense, flooded  foreland basin that developed in the center of the continent. During the Cretaceous, the Western Interior Seaway inundated most of the interior of North America including the GSENM area in southern Utah, leaving a vast array of sediments as its shoreline changed and sealevel rose and fell with deposits such as the region's Dakota Formation deposited in coastal areas ahead of the encroaching sea. The Tropic Shale represents muds deposited at the bottom of the sea. The Straight Cliffs, Wahweap and Kaiparowits Formations represent sediments that were deposited on a piedmont belt between the mountains and the sea, after the sea retreated to the east.

These events left their deposits after which Paleogene uplift and dissection painted the finishing touches on the canvas of the landscape. On the map below at about 85 Ma, note the location of the Sevier Highlands, its associated thrust fault, and the future landform of the Kaiparowits Plateau. The Straight Cliffs-Fiftymile Mountain boundary between it and the Escalante Canyons section to the east formed after Laramide uplift of the Colorado Plateau and the subsequent dissection of the region locally by tributaries of the Colorado River System into the deposits of the Glen Canyon Group.

THE REGIONAL GEOLOGY
THE CLIFFS
The northwest to southeast-trending Straight Cliffs looks somewhat like the east to west-trending Book Cliffs located further to the north, formed under similar depositional conditions and time frames. The former’s trend is roughly parallel and the latter’s trend is roughly perpendicular to the ancient shoreline of the Western Interior Seaway where they were deposited nearly 90 million years ago during the Late Cretaceous. The Straight Cliffs are composed of dark gray, massive marine shales interbedded with tan sandstones. They contain a diverse fluvial and marine architecture of offshore, shoreface, coastal plain, paludal and fluvial facies that reflect the transgressive-regressive whim of the seaway's fluctuations in sealevel. With the mind's eye staring at the Straight Cliffs, you can see layer after layer of ancient beaches and barrier islands formed by the shifting shoreline similar to the Atlantic Coast of today.

The majority of the cliffs are composed of the Straight Cliffs Formation's John Henry Member, a slope and ledge-former, representing thick beach sandstone beds separated by muddy sandstones deposited in a shoreline environment. The John Henry also contains thick, lagoonal coal deposits. Two members form the base of the cliffs, the Smoky Hollow Member (back-beach and lagoonal deposits) and resting on the Tibbett Canyon Member (offshore sandstones).

THE BENCH
Fiftymile Bench is built on the Late Jurassic Morrison Formation, much of which is covered by colluvium and landslide debris derived from the overlying Straight Cliffs Formation. Beneath the bench’s debris, windows of the underlying gray, muddy Tropic Shale and thin Dakota Formation are present. In places, Pleistocene-age, mass wasting deposits have cascaded over the bench’s lower cliffs and ledges in the Morrison Formation's Salt Wash Member to the desert-flats below. In one particular locale, seen from a distance, the erosional process of a flow is evident in the formation of hoodoos (below).

THE FLATS
The Hole-in-the-Rock Road basically follows a strike valley in the Middle Jurassic Carmel Formation. Below Escalante the road is near the top of the Paria River Member of the Carmel but soon enters the Winsor Member. Prominent landforms projecting above the Carmel desert (such as Sooner Rocks where we made camp), are composed of the orange-brown Gunsight Butte Member of the Entrada Sandstone. As the road undulated with the terrain, it weaved on and off of benches of unconsolidated Pleistocene and Holocene mixed eolian and alluvial deposits, and Entrada Sandstone. The overlying, softer, slope-forming Cannonville Member of the Entrada contains more clay and silt. To the east of the road, washes, slots and narrow intricate canyons exhibit the contact with the Windsor Member of the Carmel Formation. These dissections merge into larger corridors that eventually fuse with the Escalante River gorge, which ultimately joins the Colorado River, today drowned by Lake Powell.

This map of the GSENM illustrates the relationship of its three sections and the geological boundary that the Straight Cliffs and Fiftymile Mountain form between the Kaiparowits and Escalante sections. Also notice the Hole-in-the-Rock Road paralleling the strike of the cliffs from Escalante to the southeast towards the Colorado River and Lake Powell. The Kaiparowits Plateau is roofed with marine, fluvial and floodplain deposits; whereas, the Escalante Canyons have been unroofed of such until east of the Waterpocket Fold. 

Here's a bedrock map at the Straight Cliffs-Fiftymile Mountain boundary zone. Note the Hole-in-the-Rock Road running from Escalante to Lake Powell. 

  

Stratigraphic column in the region of the Straight Cliffs (circled)

THE SIGHTS
Having departed from the town of Escalante, we headed south on the Hole-in-the-Rock Road. This view looks back to the north toward Escalante with the Straight Cliffs located to the west. The photo was taken while literally standing on the Mormon's Hole-in-the Rock trail through the desert. Our SUV, off to the right, is parked on the Hole-in-the-Rock Road. After having been constructed over 130 years ago and having been used for only one year by Mormon pioneers, you can still see the swales created by the Conestoga wagon wheels through the red Carmel soil.

Continuing our journey south on the Hole-in-the-Rock Road for fifty miles or so, we turned off towards the cliffs and took a scenic detour on Fiftymile Bench Road. The road uses a landslide over Morrison cliffs to gain access onto Fiftymile Bench. Seen below, we ascended numerous switchbacks on a rugged road that led us to the top of the debris flow that came off the bench. The view of the desert flats far below (at about 4,300 feet above sea level) in the Carmel formation, and the Escalante Canyons and watershed of the Escalante River in the distance was quite spectacular.

Unbeknownst to us at the time, we were to make camp that night at Sooner Rocks, the barely visible, rocky outcrop in the center of the photo. The debris flow (at about 5,600 feet) on which we were ascending is comprised of an unconsolidated rocky mix largely from the Straight Cliffs above. You can spot the array of boulders in the foreground that have cascaded down from the cliffs and the road snaking upward from below. Also notice a cusp of the Fiftymile Bench extending off to the left in the Morrison Formation. About 50 miles away, the Henry Mountain laccolithic complex is faintly discernible at the horizon to the right (north-northeast)  beyond the Waterpocket Fold, while Boulder Mountain capped in Tertiary lava flows is far to the left (north-northwest). 

With sunset rapidly approaching and the wind picking up, we began an earnest search for a good spot for camp. Every desirable campsite with a sheltered wind-break seemed taken. Eventually we settled on Sooner Rocks for camp just off the Hole-in-the-Rock Road, built of smooth, slick, red Entrada Sandstone in the form of a cluster of resistant, domed, bare-rock outcrops. At sundown the temps began to drop and the wind began to gust at 40 mph plus. We set up camp, staked and secured our tents, opened a fine bottle of wine and watched the sun set, while bracing for a storm at night that never really came.

“Goodnight stars, goodnight air, goodnight noises everywhere.”

From Goodnight Moon by Margaret Wise Brown

In the morning, we awakened to a light rain and a spectacular cloud break at sunrise that ignited the Sooner Rocks in brilliant Entrada-orange. Like the Navajo Sandstone, the Entrada Sandstone exhibits large-scale eolian cross-bedding and weathers to smooth surfaces. Notice its swirly, undulating cross-beds which have been selectively etched-out by erosion. It reminded me of graded fields back home in the northeast that had been harvested of corn. Also, notice the criss-crossing, wavy and anastomosing, whitish network of deformation bands on the sandstone-dome. Probably of tectonic origin, they are indicative of accommodation to normal slip-movements, many exhibiting offsets. Their lighter, white color is likely attributable to variable bleaching through interaction with hydrocarbon-bearing solutions or other reducing agents, and indicative of the host sandstone's permeability early in its developmental history. Geochemical modeling implies the removal of some iron by fluids after chemical reduction, further contributing to their color.

As the rising sun illuminated the nearer bench portion of the escarpment to the west, we noticed a dusting of snow along the top of the Straight Cliffs, highly atypical for late May. Exquisite!

After investigating a few slot canyons in the area, we returned to the Hole-in-the-Rock Road and headed north, back to Escalante. This view nicely shows the banded stratigraphy of the Straight Cliffs, the Fiftymile Bench in the multi-colored Morrison Formation, and the heavily vegetated, Carmel desert on which we've been traveling.

“Now...Bring me that horizon" (Pirates of the Caribbean)


Highly Suggested Reading: Geology of Utah's Parks and Monuments by the Utah Geological Association and Bryce Canyon Natural History Association, Second Edition, 2003.

The Grand Staircase section of the Grand Staircase-Escalante National Monument

Good viewing spots of the entire staircase are hard to come by. The curvature of the Earth also obstructs distant areas from view. One of the best is south of Kanab, Utah along Route 89A in Arizona, somewhat north of the Grand Canyon, which is where this photo was taken.

 

 

 

President Clinton created the 1.9-million-acre Grand Staircase-Escalante National Monumenton September 18, 1996. Placed under the management of the U.S. Bureau of Land Management, it is located in south-central Utah. The monument is located within the Colorado Plateau physiographic province, near its western margin. It contains an astounding array of paleontological, geological, archaeological, biological and historical resources. Largely located in a remote area, it is comprised of mesas and cliffs, and canyons and plateaus, and distinguished by colorful geologic formations.  

 

The three sections of the Grand Staircase-Escalante National Monument:
the Grand Staircase section in blue; the Kaiparowits Basin section in yellow;
and the Escalante Canyons section in green.
From Geology of Grand Staircase-Escalante National Monument, Utah by Doelling et al

 

Cross-sectional Diagram of the Grand Staircase

from Geology of Grand Staircase-Escalante National Monument by Doelling et al 

RISERS AND CLIFFS, STEPS AND BENCHES 

The monument is divided into three geographical sections from west to east; the Grand Staircase, the Kaiparowits Basin and Escalante Canyons. More than 275 million years of Earth’s history are exposed in its rock formations extending from the Permian to the Cretaceous. The Grand Staircase section encompasses the western third of the monument. It refers to an immense sequence of sedimentary rock layers that form a series of topographic benches and cliffs that steps up in elevation progressively from south to north.

The staircase's risers correspond to cliffs, each rising as much as 2,000 feet, and the steps correspond to the benches, terraces, or plateaus in the staircase. The staircase generally includes the region from the Kaibab Uplift and Plateau, which forms the north rim of the Grand Canyon at the bottom of the staircase, to the Pink Cliffs of Bryce Canyon, at the top. 

GENESIS OF THE STAIRCASE 

The Grand Staircase began to form when vast Cambrian oceans lapped onto the broad continental shelves of the still-forming North American continent. Later, Triassic rivers and streams in their flood stages left silty and muddy deposits on the ancient landscape. Then, sandy “seas” the size of the Sahara deposited windblown sand dunes during the Jurassic. Next an enormous, shallow inland, Cretaceous sea left mud, silt and sand on its fluctuating shoreline and sea floor. Lastly, a Paleogene system of lakes deposited layer after layer of their limey deposits.

All these ancient geological events occurred in succession, one after the other, depositing a legacy of their presence that was written in stone. Laramide uplift elevated and tilted the staircase's Paleozoic and largely Mesozoic rocks to their existing location, along with the Colorado Plateau as a whole and the Grand Canyon to the south. As erosion attacked the staircase, scarps formed where several soft layers were capped by harder ones. The scarps are aligned approximately  northwest, parallel to the strike of the strata, given the northeast dip of the staircase. Subsequently, erosion retreats the strata to the northeast, down the dip of the strata. 

The Stratigrpahic Units of the Grand Staircase
from Bryce Canyon National Park and the Grand Staircase by Foos

 

COLORED CLIFFS

The cliffs are named by their colors. Starting from the bottom, they are the low cuestas of the Chocolate Cliffs capped by the resistant, Triassic sandstone of the Shinarump Conglomerate, the grand Vermilion and White Cliffs held up by the Wingate and Navajo Sandstones respectively, the Gray Cliffs of Cretaceous shales and sandstones, and at the top, the Paleogene Claron Formation comprising the Pink Cliffs. 

 

The Stratigraphic Units of the Grand Staircase

from Bryce Canyon National Park and the Grand Staircase by Foos

This diagram shows the Grand Staircase from the bottom of the Grand Canyon to the very top at Bryce Canyon.
The vertical perspective is greatly exaggerated. The lower diagram, drawn to more realistic proportions,
is more realistic of the actual topography. Click the diagram for a larger version. Diagrams from Ancient Landscapes of the Colorado Plateau by Ron Blakey (Colorado Plateau Geosystems, Inc.) and Wayne Ranney.
P.S. This book is a must read!

Probably named by the early geologist Clarence Dutton in the 1880’s, the Grand Staircase’s alternating configuration of southward-facing cliffs, terraces, and slopes is due to the varied erosion rates of the different rock types. Harder rocks, such as sandstone and limestone, erode slowly and make up the cliffs and terraces. Softer rocks, such as shale and siltstone, erode faster and make up the slopes. This high, rugged, and remote region, where bold plateaus and multi-hued cliffs run for distances that defy human perspective, was the last place in the continental U.S. to be mapped.