The new river captured the older drainage to form the ancestral Colorado River, which in turn started to form the Grand Canyon. Wetter climates brought upon by ice ages starting 2 million years ago greatly increased excavation of the Grand Canyon, which was nearly as deep as it is now, 1.2 million years ago. Volcanic activity deposited lava over the area 1.8 million to 500,000 years ago. At least 13 lava dams blocked the Colorado River, forming lakes that were up to deep. The end of the last ice age and subsequent human activity has greatly reduced the ability of the Colorado River to excavate the canyon.
Introduction
Geology of the Grand Canyon area
Geology of the Grand Canyon area | Introduction
Yes, Colorado River Yes, Colorado River. Yes, Colorado River. Yes, Colorado River
are the oldest rocks in the world in the grand canyon
user
Yes, the rock layers exposed in the Grand Canyon and in the Grand Canyon National Park area range in age from about 200 million to nearly 2 billion years old.
assistant
is there any river flowing through or alongside it?
user
Below the confluence with the Little Colorado River, the river swings west into Granite Gorge, the most dramatic portion of the Grand Canyon, where the river cuts up to into the Colorado Plateau, exposing some of the oldest visible rocks on Earth, dating as long ago as 2 billion years. The of the river that flow through the Grand Canyon are largely encompassed by Grand Canyon National Park and are known for their difficult whitewater, separated by pools that reach up to in depth.
Colorado River | Course
In 1963 Glen Canyon Dam and other dams farther upstream started to regulate the flow of the Colorado River through Grand Canyon. Pre-dam but still historic flows of the Colorado through Grand Canyon ranged from per second with at least one late 19th century flood of per second. Discharge from Glen Canyon Dam exceeds per second only when there is danger of overtopping the dam or when the level of Lake Powell otherwise needs to be lowered. An interim conservation measure since 1991 has held maximum flows at per second even though the dam's power plant can handle per second more flow.
Geology of the Grand Canyon area | Ongoing geology and human impact
Rifting started to create the Gulf of California far to the south 6 to 10 million years ago. Around the same time, the western edge of the Colorado Plateau may have sagged slightly. Both events changed the direction of many streams toward the sagging region and the increased gradient caused them to downcut much faster. From 5.5 million to 5 million years ago, headward erosion to the north and east consolidated these streams into one major river and associated tributary channels. This river, the ancestral Lower Colorado River, started to fill the northern arm of the gulf, which extended nearly to the site of Hoover Dam, with estuary deposits.
Geology of the Grand Canyon area | Colorado River: origin and development
At the same time, streams flowed from highlands in central Arizona north and across what is today the western Grand Canyon, possibly feeding a larger river. The mechanism by which the ancestral Lower Colorado River captured this drainage and the drainage from much of the rest of the Colorado Plateau is not known. Possible explanations include headward erosion or a broken natural dam of a lake or river. Whatever the cause, the Lower Colorado probably captured the landlocked Upper Colorado somewhere west of the Kaibab Uplift. The much larger drainage area and yet steeper stream gradient helped to further accelerate downcutting.
Geology of the Grand Canyon area | Colorado River: origin and development
The new river captured the older drainage to form the ancestral Colorado River, which in turn started to form the Grand Canyon. Wetter climates brought upon by ice ages starting 2 million years ago greatly increased excavation of the Grand Canyon, which was nearly as deep as it is now, 1.2 million years ago. Volcanic activity deposited lava over the area 1.8 million to 500,000 years ago. At least 13 lava dams blocked the Colorado River, forming lakes that were up to deep. The end of the last ice age and subsequent human activity has greatly reduced the ability of the Colorado River to excavate the canyon.
Geology of the Grand Canyon area | Introduction
This part of the river bisects the -high Kaibab Uplift and passes seven plateaus (the Kaibab, Kanab, and Shivwits plateaus bound the northern part of the canyon and the Coconino bounds the southern part). Each of these plateaus are bounded by north–south-trending faults and monoclines created or reactivated during the Laramide orogeny. Streams flowing into the Colorado River have since exploited these faults to excavate their own tributary canyons, such as Bright Angel Canyon.
Geology of the Grand Canyon area | Colorado River: origin and development
Ice ages during the Pleistocene brought a cooler and wetter pluvial climate to the region starting 2 to 3 million years ago. The added precipitation increased runoff and the erosive ability of streams (especially from spring melt water and flash floods in summer). With a greatly increased flow volume the Colorado cut faster than ever before and started to quickly excavate the Grand Canyon 2 million years before present, almost reaching the modern depth by 1.2 million years ago. The resulting Grand Canyon of the Colorado River trends roughly east to west for between Lake Powell and Lake Mead. In that distance, the Colorado River drops and has excavated an estimated of sediment to form the canyon.
Geology of the Grand Canyon area | Colorado River: origin and development
The age of the Western Grand Canyon is controversial, with evidence both of an old Mesozoic and a young Neozoic age. In the former case, it is possible that the river created an early Grand Canyon during the Campanian or the Paleocene. The California River has been proposed to explain the origin of the deltaic Colton Formation, as it has a high volume and similar source rocks are rare in the area of the Uinta Basin. Rock formations of similar origin occur in southeastern California and southwestern Arizona and may have been located along the same drainage. Eroded material from the Kaiparowits Formation probably did not contribute much to the formation of the Colton Formation.
California River | Geological history and present-day evidence
Controlling river flow by use of dams has diminished the river's ability to scour rocks by substantially reducing the amount of sediment it carries. Dams on the Colorado River have also changed the character of the river water. Once both muddy and warm, the river is now clear and averages a temperature year-round. Experimental floods approaching the per second level mentioned above have been carried out in 1996 and 2004 to study the effects on sediment erosion and deposition. Grand Canyon lies on the southern end of the Intermountain West seismic belt. At least 35 earthquakes larger than 3.0 on the Richter Scale occurred in the Grand Canyon region in the 20th century.
Geology of the Grand Canyon area | Ongoing geology and human impact
Since the demise of these dams the Colorado River has carved a maximum of about into the rocks of the Colorado Plateau
Geology of the Grand Canyon area | Volcanic activity in the western canyon
Streams draining the Rocky Mountains in early Miocene time terminated in landlocked basins in Utah, Arizona and Nevada but there is no evidence for a major river. Around 18 million years ago, tensional forces started to thin and drop the region to the west, creating the Basin and Range Province. Basins (grabens) dropped down and mountain ranges (horsts) rose up between old and new north–south–trending faults. However, for reasons poorly understood, the beds of the Colorado Plateaus remained mostly horizontal through both events even as they were uplifted about in two pulses. The extreme western part of the canyon ends at one of the Basin and Range faults, the Grand Wash, which also marks the boundary between the two provinces.
Geology of the Grand Canyon area | Uplift and nearby extension
In places, the San Juan has entrenched its ancient meanders thousands of feet into the bedrock, as can be observed in Goosenecks State Park, where it winds through a set of horseshoe bends while traveling a straight-line distance of only . The canyon cutting was accelerated during the Pleistocene Ice Ages when the climate of the area was much wetter, resulting in floods of up to (ten times larger than anything recorded on the San Juan in human history). The San Juan River flows through highly erodible sedimentary rock including sandstone, siltstone and shale, such as the slide-prone Chinle Formation.
San Juan River (Colorado River tributary) | Geology
Monthly average flows in the springtime average several hundred cfs and can reach . Only the upper reaches of the river above St. Johns, and the lowermost stretch below Cameron, flow year round; the middle section is basically a huge arroyo that carries water only during the wet seasons. According to a streamflow gauge near Cameron, before the river enters the Grand Canyon, the river's average annual flow was from 1948 to present. The highest annual average was in 1973, and the lowest was in 2000. The river's peak flows can be far higher than its average flow, because of quick desert runoff from cloudbursts.
Little Colorado River | Discharge
Also fossilized are tracks from lizard-like creatures and what look like tracks from millipedes and scorpions. An unconformity marks the top of this formation. Next in the geologic column is the -thick Toroweap Formation (see 6c in figure 1). It consists of red and yellow sandstone and shaly gray limestone interbedded with gypsum. The formation was deposited in a warm, shallow sea as the shoreline transgressed (invaded) and regressed (retreated) over the land. The average age of the rock is about 273 million years. In modern times it is a ledge- and slope-former that contains fossils of brachiopods, corals, and mollusks along with other animals and various terrestrial plants.
Geology of the Grand Canyon area | Hermit, Coconino, Toroweap, and Kaibab
The Toroweap is divided into the following three members: Seligman is a slope-forming yellowish to reddish sandstone and siltstone. Brady Canyon is a cliff-forming gray limestone with some chert. Wood Ranch is a slope-forming pale red and gray siltstone and dolomitic sandstone. An unconformity marks the top of this formation. One of the highest, and therefore youngest, formations seen in the Grand Canyon area is the Kaibab Limestone (see 6d in figure 1). It erodes into ledgy cliffs that are thick and was laid down in latest early Permian time, about 270 million years ago, by an advancing warm, shallow sea.
Geology of the Grand Canyon area | Hermit, Coconino, Toroweap, and Kaibab
Volcanic activity started in Uinkaret volcanic field (in the western Grand Canyon) about 3 million years ago. Over 150 flows of basaltic lava dammed the Colorado River at least 13 times from 725,000 to 100,000 years ago. The dams typically formed in weeks, were long, high (thicker upstream and thinner downstream) and had volumes of . The longevity of the dams and their ability to hold Colorado River water in large lakes has been debated. In one hypothesis water from the Colorado River backed up behind the dams in large lakes that extended as far as Moab, Utah. Dams were overtopped in short time; those that were high were overtopped by their lakes in 2 to 17 days.
Geology of the Grand Canyon area | Volcanic activity in the western canyon
The ancestral Dolores River is believed to have flowed south to join the San Juan River near the Four Corners in what is now northwestern New Mexico. The uplift of Sleeping Ute Mountain about 70 million years ago diverted the Dolores River to its present northward course, causing it to carve the Dolores River Canyon on its way to the Colorado River, creating unusual geologic features such as the Paradox Valley. The Dolores Canyon exposes rocks ranging from 300-million-year-old Pennsylvanian limestone to the 140-million-year-old Entrada sandstone deposited during the Jurassic. A cap of Cretaceous Dakota sandstone forms most of the upper rim of the canyon.
Dolores River | Geology
Here, the San Juan River, carrying runoff from the southern slope of Colorado's San Juan Mountains, joins the Colorado from the east. The Colorado then enters northern Arizona, where since the 1960s Glen Canyon Dam near Page has flooded the Glen Canyon reach of the river, forming Lake Powell for water supply and hydroelectricity generation. In Arizona, the river passes Lee's Ferry, an important crossing for early explorers and settlers and since the early 20th century the principal point where Colorado River flows are measured for apportionment to the seven U.S. and two Mexican states in the basin. Downstream, the river enters Marble Canyon, the beginning of the Grand Canyon, passing under the Navajo Bridges on a now southward course.
Colorado River | Course
The end of the Pleistocene ice ages and the start of the Holocene began to change the area's climate from a cool, wet pluvial one to dryer semi-arid conditions similar to that of today. With less water to cut, the erosive ability of the Colorado was greatly reduced. Mass wasting processes thus began to become relatively more important than they were before. Steeper cliffs and further widening the Grand Canyon and its tributary canyon system occurred. An average of two debris flows per year reach the Colorado River from tributary canyons to form or expand rapids. This type of mass wasting is the main way the smaller and steeper side canyons transport sediment but it also plays a major role in excavating the larger canyons.
Geology of the Grand Canyon area | Ongoing geology and human impact
This may have been the ancestral Dolores River, before the uplift of the Ute Mountains diverted it to its present northerly course. When the San Juan Basin filled and overflowed, it formed an outflow channel west into the old Dolores River bed, establishing the San Juan River's modern course. Tectonic forces about 2–3 million years ago caused the terrain to rise across the Monument Upwarp in southeast Utah and northeast Arizona, and the river maintained its course as an antecedent stream. The Monument Upwarp consists of a series of parallel anticlines and synclines running generally north to south, in an area roughly long and wide; where the river passes through these formations it has sliced deep canyons through the distinctively reddish rock.
San Juan River (Colorado River tributary) | Geology
We know that the shoreline was transgressing (advancing onto land) because finer grade material was deposited on top of coarser-grained sediment. Today, the Tonto Group makes up the Tonto Platform seen above and following the Colorado River; the Tapeats Sandstone and Muav Limestone form the platform's cliffs and the Bright Angel Shale forms its slopes. Unlike the Proterozoic units below it, the Tonto Group's beds basically lie in their original horizontal position. The Bright Angel Shale in the group forms an aquiclude (barrier to groundwater seeping down), and thus collects and directs water through the overlying Muav Limestone to feed springs in the Inner Gorge.
Geology of the Grand Canyon area | Tonto Group
The major sedimentary rock units exposed in the Grand Canyon range in age from 200 million to 600 million years and were deposited in warm shallow seas and near-shore environments. The nearly 40 identified rock layers of Grand Canyon form one of the most studied geologic columns in the world. The oldest exposed formation in Zion National Park is the youngest exposed formation in the Grand Canyon – the ~240‑million-year-old Kaibab Limestone. The Bryce Canyon area to the northeast continues where the Zion area leaves off by presenting Cenozoic-aged rocks that are 100 million years younger. In fact the youngest formation seen in the Zion area is the oldest exposed formation in Bryce Canyon – the Dakota Sandstone.
Grand Staircase | Geology
Like the Supai Group below it, the Permian-aged Hermit Formation was probably deposited on a broad coastal plain (see 6a in figure 1). The alternating thin-bedded iron oxide, mud and silt were deposited via freshwater streams in a semiarid environment around 280 million years ago. Fossils of winged insects, cone-bearing plants, and ferns are found in this formation as well as tracks of vertebrate animals. It is a soft, deep red shale and mudstone slope-former that is approximately thick. Slope development will periodically undermine the formations above and car- to house-sized blocks of that rock will cascade down onto the Tonto Platform.
Geology of the Grand Canyon area | Hermit, Coconino, Toroweap, and Kaibab
The present-day Salton Sea can be considered the most recent incarnation of Lake Cahuilla, though on a much smaller scale. Between 1.8 million and 10,000 years ago, massive flows of basalt from the Uinkaret volcanic field in northern Arizona dammed the Colorado River within the Grand Canyon. At least 13 lava dams were formed, the largest of which was more than high, backing the river up for nearly to present-day Moab, Utah. The lack of associated sediment deposits along this stretch of the Colorado River, which would have accumulated in the impounded lakes over time, suggests that most of these dams did not survive for more than a few decades before collapsing or being washed away.
Colorado River | Geology
The clues to the ancient origins of this canyon lie somewhere at the 2 mile deep downstream mouth of the canyon in a huge sedimentary bed called the Monterey Fan. This fan appears to be far too massive to have accumulated from the modern coastal streams. Research including core sampling is ongoing. Thus far, only "recent" sedimentary cores have been obtained. The oldest cores lie deeply buried, and remain to be probed. Once these deeper core samples have been properly analyzed and traced back to their original sedimentary sources, the answers to such speculations as to which river might have provided the high level of turbidity current flows which are believed to have most probably been required to carve out such a deep and long canyon, with such a huge sedimentary deposit (fan) at its mouth will all hopefully be finally resolved.
Monterey Canyon | Geomorphology
Of these, five registered over 5.0 on the Richter Scale and the largest was a 6.2 quake that occurred in January 1906. Major roughly north–south-trending faults that cross the canyon are (from west to east), the Grand Wash, Hurricane and Toroweap. Major northeast-trending fracture systems of normal faults that intersect the canyon include the West Kaibab and Bright Angel while northwest-trending systems include the Grandview—Phantom. Most earthquakes in the region occur in a narrow northwest-trending band between the Mesa Butte and West Kaibab fracture systems. These events are probably the result of eastward-migrating crustal stretching that may eventually move past the Grand Canyon area.
Geology of the Grand Canyon area | Ongoing geology and human impact
Dox Formation is over thick and is made of sandstone with some interbedded shale beds and mudstone that were deposited in fluvial and tidal environments. Ripple marks and other features indicate it was close to the shore. Outcrops of this red to orange formation can be seen in the eastern parts of the canyon. Fossils of stromatolites and algae are found in this layer. At 1070 ± 70 million years old, the Cardenas Basalt is the youngest formation in the Unkar Group. It is made of layers of dark brown basaltic rocks that flowed as lava up to thick. Nankoweap Formation is around 1050 million years old and is not part of a group.
Geology of the Grand Canyon area | Grand Canyon Supergroup
While some aspects about the history of incision of the canyon are debated by geologists, several recent studies support the hypothesis that the Colorado River established its course through the area about 5 to 6 million years ago. Since that time, the Colorado River has driven the down-cutting of the tributaries and retreat of the cliffs, simultaneously deepening and widening the canyon.
Grand Canyon | Introduction
Geologically, the Rio Grande Gorge is a canyon, carved out by erosion over the last several million years. The Rio Grande Gorge and its river follow a topographical low within the larger Rio Grande Rift; a mixture of volcanic activity, shifting tectonic plates, and erosion out of layers of gravels and lava yielded the recognizable narrow, deep gorge visible today.
Rio Grande Gorge | Geology
The creek is fed from Tapeats Spring, the largest Spring in the Grand Canyon. In 1970, the spring was estimated to discharge of water per day into the creek from the Muav Limestone. A small amount of surface water can also flow into the creek. Since the spring flows year round, the creek is a perennial stream.
Tapeats Creek | Sources
Uplift from the Laramide orogeny and the creation of the Basin and Range province worked together to steepen the gradient of streams flowing west on the Colorado Plateau. These streams cut deep, eastward-growing, channels into the western edge of the Colorado Plateau and deposited their sediment in the widening Basin and Range region.
Geology of the Grand Canyon area | Uplift and nearby extension
Dams in particular have upset patterns of sediment transport and deposition. Controlled floods from Glen Canyon Dam upstream have been conducted to see if they have a restorative effect. Earthquakes and mass wasting erosive events still affect the region.
Geology of the Grand Canyon area | Introduction
Over millions of years, the bedrock was pushed up to over above sea level. Approximately 35 million years ago, rainfall flowed into the rock, and eroded passages that lead to the Colorado River and what is now the Grand Canyon. Millions of years later, the evaporating water left calcium deposits on the walls and floors, creating the formations that can be viewed today.
Grand Canyon Caverns | Introduction
The geology of the Grand Canyon area includes one of the most complete and studied sequences of rock on Earth. The nearly 40 major sedimentary rock layers exposed in the Grand Canyon and in the Grand Canyon National Park area range in age from about 200 million to nearly 2 billion years old. Most were deposited in warm, shallow seas and near ancient, long-gone sea shores in western North America. Both marine and terrestrial sediments are represented, including lithified sand dunes from an extinct desert. There are at least 14 known unconformities in the geologic record found in the Grand Canyon.
Geology of the Grand Canyon area | Introduction
There are, however, shared rock units between all three, creating a super-sequence of formations that geologists call the Grand Staircase. Bryce Canyon's formations are the youngest known units in the Grand Staircase. Younger rock units, if they ever existed, have been removed by erosion. These layers have undergone 5000 to 10,000 feet (1500 to 3000 m) of uplift starting about 66 million years ago with the Laramide orogeny which has increased the ability of the Colorado River to cut its channel to make individual plateaus out of the Colorado Plateaus region. The major canyons of the region did not start to form until about five to six million years ago when the Gulf of California opened up and thus lowered the river's base level (its lowest point).
Grand Staircase | Geology
Streams were the likely cause, but marine scour may be to blame. Either way, these depressions were filled with freshwater limestone about 385 million years ago in the Middle Devonian in a formation that geologists call the Temple Butte Formation (see 4a in figure 1). Marble Canyon in the eastern part of the park displays these filled purplish-colored channels well. Temple Butte Formation is a cliff-former in the western part of the park where it is gray to cream-colored dolomite. Fossils of animals with backbones are found in this formation; bony plates from freshwater fish in the eastern part and numerous marine fish fossils in the western part.
Geology of the Grand Canyon area | Temple Butte, Redwall, and Surprise Canyon
It is believed that there is another of vertical bedrock that the Virgin River can still erode. Mass wasting, often caused by ice wedging into cracks in the canyon walls, is another force that widens the valley. The Navajo Sandstone formation is easily eroded and is known to be very porous. Unstable geology is prevalent throughout the canyon, and occasional rockslides have formed impounded lakes in the canyon, the most recent of which was roughly 4,000 years ago. Owing to the extreme depth of the canyon, there are many springs fed by the surrounding groundwater, permitting water in the canyon to run year round.
Zion Canyon | Geology and history
The flow of water from the Grand Canyon region may have stopped around 16 million years ago due to eruptions of the Yellowstone hot spot. Isostatic depression of the crust by ice sheets during the Pleistocene deprived the Saglek Basin of sediment as rivers drained directly into the newly formed Hudson Bay. Much of the river's flow was taken up by the Mackenzie River Basin, leaving the Saskatchewan River and Nelson River as the last remnants of the system.
Paleo-Bell River | End of the river system
Drainage of the Colorado Plateau was significantly altered by the opening of the Gulf of California. Rifting tore Baja California Peninsula northwestward from the Mexican mainland starting some 10 to 5 mya. The ancestral Colorado River responded to the regional downwarping by taking a shortcut to the sea by flowing into the new gulf. This significantly decreased the distance from the river's headwaters and its delta at the sea. Water in the Colorado and its tributaries moved faster as a result and cut down deeper, creating the canyonland topography. Formation of approximately the current depth of the Colorado River's Grand Canyon by 1.2 mya further caused its tributaries to cut down even deeper.
Geology of the Bryce Canyon area | Modern drainage and erosion
There are 33 crustacean species found in the Colorado River and its tributaries within Grand Canyon National Park. Of these 33, 16 are considered true zooplankton organisms. Only 48 bird species regularly nest along the river, while others use the river as a migration corridor or as overwintering habitat. The bald eagle is one species that uses the river corridor as winter habitat.
Grand Canyon | Lower Sonoran
Geologically Zion Canyon is part of the Navajo sandstone Colorado Plateau, which contained many joints and cracks when first uplifted, one of which was cut by the North Fork of the Virgin River to become Zion Canyon. The river was the largest force in cutting the canyon, mostly by flash floods, as the average flow of the river is very light. This relatively quick downcutting has left many seasonal tributaries with hanging valleys. Some of the largest tributaries have cut down to nearly an equal elevation as the valley floor. Erosion continues to sculpt the canyon walls, creating natural arches and other rock formations.
Zion Canyon | Geology and history
Formations totaling over in thickness were deposited in the region in the Mesozoic and Cenozoic but were almost entirely removed from the Grand Canyon sequence by subsequent erosion. The geology of the Zion and Kolob canyons area and the geology of the Bryce Canyon area records some of these formations. All these rock units together form a super sequence of rock known as the Grand Staircase.
Geology of the Grand Canyon area | Mesozoic deposition
In addition to the Grijalva, there are other flows of water in the area in and around the canyon, many of which are seasonal. These consist of streams, some of which form waterfalls on the canyon's sides, and underground movements which have created caves and karst formations. The last important water formation in the area is the manmade reservoir of the Chicoasén Dam. The canyon proper is deep and narrow, characterized by vertical walls. As the gap changes direction as much as 90 degrees in places, it separates the Meseta de las Animas mesa in the west from the Meseta de Ixtapa mesa in the east.
Sumidero Canyon | Geology
An unconformity marks the top of this formation . Coconino Sandstone formed about 275 million years ago as the area dried out and sand dunes made of quartz sand invaded a growing desert (see 6b in figure 1). Some Coconino fills deep mudcracks in the underlying Hermit Shale and the desert that created the Coconino lasted for 5 to 10 million years. Today, the Coconino is a thick golden white to cream-colored cliff-former near the canyon's rim. Cross bedding patterns of the frosted, fine-grained, well-sorted and rounded quartz grains seen in its cliffs is compatible with but does not substantiate conclusively an eolian environment.
Geology of the Grand Canyon area | Hermit, Coconino, Toroweap, and Kaibab
Here, the river leaves the last of the Unkar Group lower-unit members behind. Other sections of the Unkar Group reappear downstream, due to the general faulting of the Grand Canyon.
Grand Canyon Supergroup | Geology
Temple Butte Formation is thick; thinner near Grand Canyon Village and thicker in western Grand Canyon. An unconformity representing 40 to 50 million years of lost geologic history marks the top of this formation. The next formation in the Grand Canyon geologic column is the cliff-forming Redwall Limestone, which is thick (see 4b in figure 1). Redwall is composed of thick-bedded, dark brown to bluish gray limestone and dolomite with white chert nodules mixed in. It was laid down in a retreating shallow tropical sea near the equator during 40 million years of the early-to-middle Mississippian. Many fossilized crinoids, brachiopods, bryozoans, horn corals, nautiloids, and sponges, along with other marine organisms such as large and complex trilobites have been found in the Redwall.
Geology of the Grand Canyon area | Temple Butte, Redwall, and Surprise Canyon
Uplift marked the start of the Mesozoic and streams started to incise the newly dry land. Streams flowing through broad low valleys in Triassic time deposited sediment eroded from nearby uplands, creating the once -thick Moenkopi Formation. The formation is made from sandstone and shale with gypsum layers in between. Moenkopi outcrops are found along the Colorado River in Marble Canyon, on Cedar Mountain (a mesa near the southeastern park border), and in Red Butte (located south of Grand Canyon Village). Remnants of the Shinarump Conglomerate, itself a member of the Chinle Formation, are above the Moenkopi Formation near the top of Red Butte but below a much younger lava flow.
Geology of the Grand Canyon area | Mesozoic deposition
More recently, documentation of gravels characteristic of the Gunnison River and located at the western mouth of Unaweep Canyon provide evidence for occupation of the canyon by an ancestral Gunnison River Hence, the ancestral Gunnison River may have carved the canyon. However, another hypothesis holds that the ancestral Gunnison River did not carve the canyon, but exhumed a pre-existing (paleo) canyon. This hypothesis of an ancient age for the inner gorge of Unaweep Canyon comes from dating of sediments recovered in a core through the canyon fill. This core proved the existence of a thick (>300 m) sediment fill in the canyon, an idea first proposed in the 1970s on the basis of a geophysical study.
Unaweep Canyon | Recent finds
Farther downstream it receives the Dolores River and defines the southern border of Arches National Park, before passing Moab and flowing through "The Portal", where it exits the Moab Valley between a pair of sandstone cliffs. In Utah, the Colorado flows primarily through the "slickrock" country, which is characterized by its narrow canyons and unique "folds" created by the tilting of sedimentary rock layers along faults. This is one of the most inaccessible regions of the continental United States. Below the confluence with the Green River, its largest tributary, in Canyonlands National Park, the Colorado enters Cataract Canyon, named for its dangerous rapids, and then Glen Canyon, known for its arches and erosion-sculpted Navajo sandstone formations.
Colorado River | Course
Here the San Juan River flows into an area known as the San Juan Basin, where the western San Juan Basin is typified by exposures of the Fruitland and Menefee Formations. A stepped sequence of high stream terraces, present above the San Juan River and its tributaries, represents abandoned Pleistocene flood plains.
Navajo section | Geology and physiography
The Escalante River, a desert stream which runs through the sinuous slot canyons of Grand Staircase-Escalante National Monument, joins about two-thirds of the way down Lake Powell. The San Juan River, which carries runoff from the southern slopes of the San Juan Mountains and the Four Corners region in Colorado and New Mexico, joins several miles further downstream; it forms an arm of the lake nearly long. Although the San Juan contributes only about one-tenth of the Colorado River flow, it is extremely muddy, contributing as much as 40 percent of the total sediment load. The area around the confluence is dominated geographically by Navajo Mountain which rises over a mile (1.6 km) above the surrounding landscape, which is part of the Navajo Nation.
Course of the Colorado River | <a href="Utah">Utah</a>
The Grand Canyon is part of the Colorado River basin which has developed over the past 70 million years, in part based on apatite (U-Th)/He thermochronometry showing that Grand Canyon reached a depth near to the modern depth by 20 Ma. A recent study examining caves near Grand Canyon places their origins beginning about 17 million years ago. Previous estimates had placed the age of the canyon at 5–6 million years. The study, which was published in the journal "Science" in 2008, used uranium-lead dating to analyze calcite deposits found on the walls of nine caves throughout the canyon. There is a substantial amount of controversy because this research suggests such a substantial departure from prior widely supported scientific consensus.
Grand Canyon | Geology
Uplift of the region started about 75 million years ago during the Laramide orogeny; a mountain-building event that is largely responsible for creating the Rocky Mountains to the east. In total, the Colorado Plateau was uplifted an estimated . The adjacent Basin and Range Province to the west started to form about 18 million years ago as the result of crustal stretching. A drainage system that flowed through what is today the eastern Grand Canyon emptied into the now lower Basin and Range province. Opening of the Gulf of California around 6 million years ago enabled a large river to cut its way northeast from the gulf.
Geology of the Grand Canyon area | Introduction
Below Lee's Ferry the Colorado begins to trend more south than southwest, through the vertical-walled Marble Canyon which is crossed by the twin Navajo Bridges as it enters Grand Canyon National Park. At the southern end of Marble Canyon, the river is joined by another tributary, the capricious Little Colorado River, which drains the Painted Desert region of northeast Arizona and western New Mexico. Although normally a calm and clear spring-fed stream, it can rise dramatically following monsoon storms over the Colorado Plateau. Then the river then turns abruptly west directly across the folds and fault line of the plateau, through the Upper and Lower Granite Gorges of Grand Canyon, which is long and from between the upper cliffs.
Course of the Colorado River | <a href="Arizona">Arizona</a>
Headward erosion of one of those tributaries, the Paria River, eroded north-northwestward toward what is now Paria Amphitheater. The river took a route roughly parallel to and east of the Paunsaugunt Fault. Erosion from snow and rain that fall directly on the east-facing rim of the Paunsaugunt Plateau forms gullies that widen into alcoves and amphitheaters while differential erosion and frost wedging create the hoodoos. Streams on the plateau do not contribute to the formation of alcoves or amphitheaters because they flow away from the rim. Erosion continues in this fashion today.
Geology of the Bryce Canyon area | Modern drainage and erosion
Around 20,000 years ago the Grand Falls Lava Flow consisting of alkali olivine basalt proceeded along the Little Colorado River bed from a vent near Merriam crater. At Black Falls Crossing the lava flow has blocked the river channel so that when the river is flowing a ten-foot high waterfall is formed. At other times the rock is completely covered by sand.
Black Falls, Arizona | Geology
An unconformity of 15 to 20 million years separates the Supai Group from the previously deposited Redwall Formation. Supai Group was deposited in late Mississippian, through the Pennsylvanian and into the Early Permian time, some 320 million to 270 million years ago. Both marine and non-marine deposits of mud, silt, sand and calcareous sediments were laid down on a broad coastal plain similar to the Texas Gulf Coast of today. Around this time, the Ancestral Rocky Mountains rose in Colorado and New Mexico and streams brought eroded sediment from them to the Grand Canyon area. Supai Group formations in the western part of the canyon contain limestone, indicative of a warm, shallow sea, while the eastern part was probably a muddy river delta.
Geology of the Grand Canyon area | Supai Group
With the Gunnison River's course set, a broad uplift in the area 2 to 3 million years ago caused the river to cut through the softer volcanic deposits. Eventually the river reached the Precambrian rocks of the Gunnison Uplift. Since the river was unable to change its course, it began scouring through the extremely hard metamorphic rocks of the Gunnison Uplift. The river's flow was much larger than currently, with much higher levels of turbidity. As a result, the river dug down through the Precambrian gneiss and schist at the rate of every 100 years. The extreme hardness of the metamorphic rock along with the relative quickness with which the river carved through them created the steep walls that can be seen today.
Black Canyon of the Gunnison National Park | Quaternary
From there it flows west through the Navajo Nation, turning northwest near Shiprock and its namesake monolith, crossing very briefly back into southwest Colorado (within half a mile (0.8 km) of the Four Corners quadripoint) before entering southeastern Utah. West of Bluff, Utah the river slices through the Comb Ridge and enters a series of rugged winding canyons, often over in depth. The lower of the San Juan River, in a remote portion of the Glen Canyon National Recreation Area, are flooded by Lake Powell, which is formed by Glen Canyon Dam on the Colorado River. The San Juan joins the Colorado in San Juan County, Utah at a point about to the north of Navajo Mountain and northeast of Page, Arizona.
San Juan River (Colorado River tributary) | Course
Rocks that form the walls of Goat Canyon are relatively young, being no older than 10,000 years; they were formed in the Quaternary period. The west wall of the canyon is about from the ocean. The eastern wall of the canyon consists of a slope that leads to Spooner's Mesa, which was named after a couple who had a homestead atop it.
Goat Canyon (Tijuana River Valley) | Geography
The next two periods of geologic history, the Ordovician and the Silurian, are missing from the Grand Canyon sequence. Geologists do not know if sediments were deposited in these periods and were later removed by erosion or if they were never deposited in the first place. Either way, this break in the geologic history of the area spans about 65 million years. A type of unconformity called a disconformity was formed. Disconformities show erosional features such as valleys, hills and cliffs that are later covered by younger sediments. Geologists do know that deep channels were carved on the top of the Muav Limestone during this time.
Geology of the Grand Canyon area | Temple Butte, Redwall, and Surprise Canyon
Glen Canyon was carved by differential erosion from the Colorado River over an estimated 5 million years. The Colorado Plateau, through which the canyon cuts, arose some 11 million years ago. Within that plateau lie layers of rock from over 300 million years ago to the relatively recent volcanic activity. Pennsylvanian and Permian formations can be seen in Cataract Canyon and San Juan Canyon. The Moenkopi Formation, which dates from 230 million years ago (Triassic Period), and the Chinle Formation are found at Lees Ferry and the Rincon. Both formations are the result of the ancient inland sea that covered the area.
Lake Powell | Geology
Crustal extension in the Basin and Range Province began about 20 million years ago and the modern Sierra Nevada began forming about 10 million years ago, eventually diverting the Colorado southwards towards the Gulf. As the Colorado Plateau continued to rise between 5 and 2.5 million years ago, the river maintained its ancestral course (as an antecedent stream) and began to cut the Grand Canyon. Antecedence played a major part in shaping other peculiar geographic features in the watershed, including the Dolores River's bisection of Paradox Valley in Colorado and the Green River's cut through the Uinta Mountains in Utah.
Colorado River | Geology
The Laramide orogeny affected all of western North America by helping to build the American cordillera. The Kaibab Uplift, Monument Upwarp, the Uinta Mountains, San Rafael Swell, and the Rocky Mountains were uplifted, at least in part, by the Laramide orogeny. This major mountain-building event started near the end of the Mesozoic, around 75 million years ago, and continued into the Eocene period of the Cenozoic. It was caused by subduction off the western coast of North America. Major faults that trend north–south and cross the canyon area were reactivated by this uplift. Many of these faults are Precambrian in age and are still active today.
Geology of the Grand Canyon area | Uplift and nearby extension
During the Paleozoic era, the western part of what would become North America was near the equator and on a passive margin. The Cambrian Explosion of life took place over about 15 million years in this part of the world. Climate was warm and invertebrates, such as the trilobites, were abundant. An ocean started to return to the Grand Canyon area from the west about 550 million years ago. As its shoreline moved east, the ocean began to concurrently deposit the three formations of the Tonto Group. Tapeats Sandstone averages 525 million years old and is made of medium- to coarse-grained sand and conglomerate that was deposited on an ancient shore (see 3a in ).
Geology of the Grand Canyon area | Tonto Group
The Grand Staircase is an immense sequence of sedimentary rock layers that stretch south from Bryce Canyon National Park through Zion National Park and into the Grand Canyon. Within this sequence, the oldest exposed formation in the Zion and Kolob canyons area is the youngest exposed formation in the Grand Canyon—the Kaibab limestone. Bryce Canyon to the northeast continues where the Zion and Kolob areas end by presenting Cenozoic-aged rocks. In fact, the youngest formation seen in the Zion and Kolob area is the oldest exposed formation in Bryce Canyon—the Dakota Sandstone. In the Permian period, the Zion and Kolob area was a relatively flat basin near sea level on the western margin of the supercontinent Pangaea.
Geology of the Zion and Kolob canyons area | Grand Staircase and basement rocks
This waterfall is not as high, and has a smaller water flow. It is fed by several other falls streaming off the cliffs above it. Further to the left, at about twice the distance from the first falls to the second, another large stream plunges into the canyon. In total, there are at least six waterfalls feeding the canyon. At the base of the canyon, a separate slot canyon, or "The Narrows", begins. The water from the Bras de Caverne waterfall and the waterfall to its left drain into the slot canyon at a 90-degree angle, through a waterfall known informally as the "Washing Machine".
Trou de Fer | Introduction
The rapid begins after a leisurely right turn in the river and the gradient noticeably increases. Also, a large outcrop of granite on river-left that resembles a cowpie marks the entrance. At the first corner (a left turn) a particular maneuver is required to pass an obstacle known as Split Rock (also known as Cowpie Rock). This is generally navigated on river right with a hard pull back to the left. Proper navigation of Split Rock allows for the ideal set up for the remainder of the rapid. The flow is obstructed by several large boulders and the current weaves from bank to bank.
Northgate Canyon | Rapid Descriptions
Joseph Canyon contains Joseph Creek, a tributary of the Grande Ronde River, which flows into the Snake River, a tributary of the Columbia. The geology is typical of the Columbia Plateau, formed by the Columbia River Basalt Group, and the exposed canyon walls provide a striking view of flood basalt flows and dikes. The canyon floor contains sediments deposited by the Missoula Floods.
Joseph Canyon | Geography
The exact route of the passage is unknown, and dye tests have shown that the water takes over 2 hours to make its 1/4-mile underground journey. Additionally, more water flows from the Rise than enters the cavern at the Sink. The Crow Indian name of the river, "Popo Agie" (pronounced po-PO-shuh), is taken to mean "gurgling river." The canyon has a wide variety of plant species which differ depending on elevation and location. Numerous types of grass, trees, shrubs and other species of plants grow throughout the canyon. The canyon's area is generally divided into two main ecological zones: a subarid environment that is mainly populated by sagebrush and a pine-fir montane forest zone.
Sinks Canyon State Park | Natural history
This exposed the Navajo Sandstone, the surface rock found throughout the Horseshoe Bend area, which also forms the entire depth of the canyon walls of the Grand Canyon at Horseshoe Bend. This sandstone is notable for its crossbedding and iron concretions. It is likely that the Colorado River will eventually cut through the neck of the bend, producing a natural bridge like those found at Natural Bridges National Monument in Utah. The river will then abandon Horseshoe bend, leaving a cutoff meander resembling The Rincon further north along the Colorado River in Utah.
Horseshoe Bend (Arizona) | Geology
The river above the falls was shallow and much wider than the gorge. Thus, it wrapped around the lip of the main falls creating lateral falls. These flowed until the recession of the main falls denied them water. Northrup Canyon in Steamboat Rock State Park, contains a dry cataract as wide as Niagara Falls and three times as high. Steamboat Rock high and a in area, now stands as an isolated rise, but for a time it created two cataracts. When the falls passed north of Steamboat Rock, it found a granite base beneath the basal flows. Granite lacks the close vertical joints of basalt and resisted the erosion from the cataract's plunge.
Grand Coulee | Waterfall Erosion
The river in the canyon is also called Tolantongo. It is pleasantly warm, colored by mineral salts it picks up as it passes through the mountain. The water comes from a complex series of channels inside the mountain that heats the water to about 20 degrees Celsius. Much of this water dwells in niches in the rocky side of the canyon, which has a cooling effect. Another factor is that the water mixes with unheated water as it leaves the grottoes. The result is mostly tepid water outside the grottoes and in the river itself, good for swimming even on a cold day.
Tolantongo | The river
The oldest section of the supergroup is the Unkar Group. It accumulated in a variety of fluvial, deltaic, tidal, nearshore marine, and offshore marine environments. The first formation to be laid down in the Unkar Group was the Bass Formation. Fluvial gravels initially accumulated in shallow river valleys. They later lithified into a basal conglomerate that is known as the Hotauta Member of the Bass Formation. The Bass Formation was deposited in a shallow sea near the coast as a mix of limestone, sandstone, and shale. Diagenesis later altered the bulk of the limestone into dolomite. It is thick and grayish in color.
Geology of the Grand Canyon area | Grand Canyon Supergroup
Related to the proposed ancient age for the canyon is the hypothesis that the canyon was glaciated during the Late Paleozoic, roughly 300 million years ago. The hypotheses of a Paleozoic age and glacial origin for the canyon, remain debated, like many other hypotheses for the origin of this scenic canyon.
Unaweep Canyon | Recent finds
The northern end of the canyon cuts through red sandstone of the Chugwater Formation.
Wind River Canyon | Geology
The formation is typically made of sandy limestone sitting on top of a layer of sandstone. This is the cream to grayish-white rock that park visitors stand on while viewing the canyon from both rims. It is also the surface rock covering much of the Kaibab Plateau just north of the canyon and the Coconino Plateau immediately south. Shark teeth have been found in this formation as well as abundant fossils of marine invertebrates such as brachiopods, corals, mollusks, sea lilies, and worms. An unconformity marks the top of this formation.
Geology of the Grand Canyon area | Hermit, Coconino, Toroweap, and Kaibab
Averaging 1250 million years old, this is the oldest layer exposed in the Grand Canyon that contains fossils—stromatolites. Hakatai Shale is made of thin beds of marginal-marine-derived mudstones, sandstones, and shale that, together, are thick. This formation indicates a short-lived regression (retreat) of the seashore in the area that left mud flats. Today it is very bright orange-red and gives the Red Canyon its name. Shinumo Quartzite is a resistant marine sedimentary quartzite that was eroded to form monadnocks that later became islands in Cambrian time. Those islands withstood wave action long enough to become re-buried by other sediments in the Cambrian Period.
Geology of the Grand Canyon area | Grand Canyon Supergroup
As a result, the San Juan is an extremely muddy river, contributing more than half of the sediment in the upper Colorado above Lees Ferry despite accounting for only 14 percent of the total runoff. Between 1914 and 1980 the U.S. Geological Survey station at Bluff, Utah recorded an average of 25.41 million tons of sediment carried by the San Juan River each year, ranging from a minimum of 3.24 million tons in 1978 to 112.4 million tons in 1941. The majority of the sediment originates in the watershed downstream of the Animas River. Since the closure of Glen Canyon Dam in 1963, sediments have been building a delta in Lake Powell instead of continuing down the Colorado River.
San Juan River (Colorado River tributary) | Geology
In late Precambrian time, extension from a large tectonic plate or smaller plates moving away from Laurentia thinned its continental crust, forming large rift basins that would ultimately fail to split the continent. Eventually, this sunken region of Laurentia was flooded with a shallow seaway that extended from at least present-day Lake Superior to Glacier National Park in Montana to the Grand Canyon and the Uinta Mountains. The resulting Grand Canyon Supergroup of sedimentary units is composed of nine varied geologic formations that were laid down from 1.2 billion and 740 million years ago in this sea. Good exposures of the supergroup can be seen in eastern Grand Canyon in the Inner Gorge and from Desert View, Lipan Point and Moran point.
Geology of the Grand Canyon area | Grand Canyon Supergroup
The Grand Canyon Supergroup overlies the Vishnu Basement Rocks, but were never subjected to metamorphism. The units of the Supergroup were faulted and then tilted from 10 to 15 degrees. A section of the Unkar Group members is visible north of Grand Canyon Village, on the South Rim; specifically at the intersection of the Bright Angel Fault and the Grandview–Phantom Fault (which cuts through Phantom Creek), on the North Rim (at the north side of Granite Gorge). The majority of the Grand Canyon Supergroup geologic members are found in the south and south-southwest stretch of the Colorado River as it issues from Marble Canyon; traverses the southeast perimeter of the Kaibab Plateau; and flows northeasterly, entering Granite Gorge and regions of the Vishnu Basement Rocks.
Grand Canyon Supergroup | Geology
At the same time, sediment filled the lakes behind the dams. Sediment would fill a lake behind a -high dam in 10.33 months, filled a lake behind an -high dam in 345 years, and filled the lake behind the tallest dam in 3000 years. Cascades of water flowed over a dam while waterfalls migrated up-river along it. Most lava dams lasted for around 10,000 to 20,000 years. However others have proposed that the lava dams were much more ephemeral and failed catastrophically before overtopping. In this model dams would fail due to fluid flow through fractures in the dams and around dam abutments, through permeable river deposits and alluvium.
Geology of the Grand Canyon area | Volcanic activity in the western canyon
This is the resistant rock now exposed at the bottom of the canyon in the Inner Gorge. As the volcanic islands collided with the mainland around 1.7 billion years ago, blobs of magma rose from the subduction zone and intruded the Granite Gorge Metamorphic Suite. These plutons slowly cooled to form the Zoroaster Granite; part of which would later be metamorphosed into gneiss. This rock unit can be seen as light-colored bands in the darker garnet-studded Vishnu Schist (see 1b in ). The intrusion of the granite occurred in three phases: two during the initial Vishnu metamorphism period, and a third around 1.4 billion years ago.
Geology of the Grand Canyon area | Vishnu Basement Rocks
There is a gap of about a billion years between the 500-million-year-old stratum and the level below it, which dates to about 1.5 billion years ago. This large unconformity indicates a long period for which no deposits are present.
Grand Canyon | Geology
The river canyon is deep and narrow, and even in the summer sunshine only reaches the canyon bottom for a few hours. The land is mostly steep, rocky, semi-arid except for the narrow canyons, and inaccessible. The upstream river canyon is characteristic of the Ventana Wilderness region: steep-sided, sharp-crested ridges separating valleys. Upstream from the Boy Scout camp are narrow gorges, waterfalls, and a few large pools. Several northwest-trending faults cut across the Little Sur River drainage: the Sur, the Palo Colorado, and the Church Creek faults. The river flows mostly west for much of its length, unlike other rivers in the region which tend to flow to the northwest or southeast.
Little Sur River | Geology
The river drops down the canyon and intersects the bedrock layers where the underground river flows. Also at this point numerous large underground streams join and greatly amplify the flow. The canyon is constantly being eroded by the churning and swirling of the water. The effect of this has made the width across at some points and a depth of . Limestone is one of the most dominant minerals within the canyon. It was deposited in a shallow tropical sea by plankton which secrete limestone.
Maligne Canyon | Geology
Manakacha (see 5b in figure 1) is a cliff- and slope-forming pale red sandstone and red shale that averages thick in Grand Canyon. Wescogame (see 5c in figure 1) is a ledge- and slope-forming pale red sandstone and siltstone that is thick. Esplanade (see 5d in figure 1) is a ledge- and cliff-forming pale red sandstone and siltstone that is thick. An unconformity marks the top of the Supai Group.
Geology of the Grand Canyon area | Supai Group
The lower Dolores River may have once been the original course of the Colorado River, which flowed through the now dry Unaweep Canyon, currently occupied by West Creek, a small tributary of the Dolores. When the Uncompahgre Plateau was formed it diverted the larger Colorado northwards through what is now the Grand Valley, looping around through Westwater Canyon to the confluence with the Dolores in eastern Utah and leaving Unaweep Canyon as a huge dry gap across the plateau. However, some geologists contend that the Colorado never flowed through Unaweep and the lower Dolores River, as the erosive force of the river should have created a water gap here; instead, the canyon may have been formed by glaciation during the Paleozoic.
Dolores River | Geology
Ripple marks are common in the upper members of this dark brown thin-bedded layer. Fossils and imprint trails of trilobites and brachiopods have also been found in the Tapeats. Today it is a cliff-former that is thick. Bright Angel Shale averages 515 million years old and is made of mudstone-derived shale that is interbedded with small sections of sandstone and shaly limestone with a few thin beds of dolomite. It was mostly deposited as mud just offshore and contains brachiopod, trilobite, and worm fossils (see 3b in figure 1). The color of this formation is mostly various shades of green with some brownish-tan to gray parts.
Geology of the Grand Canyon area | Tonto Group
These flash floods probably happened more than once. The canyon is a classic V-shaped valley, indicative of river-type erosion rather than glaciation. Today the canyon is still being eroded by the Yellowstone River. The colors in the canyon are also a result of hydrothermal alteration. The rhyolite in the canyon contains a variety of different iron compounds. When the old geyser basin was active, the "cooking" of the rock caused chemical alterations in these iron compounds. Exposure to the elements caused the rocks to change colors. The rocks are oxidizing; in effect, the canyon is rusting. The colors indicate the presence or absence of water in the individual iron compounds.
Grand Canyon of the Yellowstone | Geology
The canyon was formed during the Miocene period (23.7–5.3 million years ago) by the river cutting into the uplifting Interior Plateau. From the northern Cariboo to Fountain, the river follows the line of the huge Fraser Fault, which runs on a north-south axis and meets the Yalakom Fault a few miles downstream from Lillooet. Exposures of lava flows are present in cliffs along the Fraser Canyon. They represent volcanic activity in the southern Chilcotin Group during the Pliocene period and the volcanic vents of their origins have not been discovered.
Fraser Canyon | Geology
In December 2012, a study published in the journal "Science" claimed new tests had suggested the Grand Canyon could be as old as 70 million years. However, this study has been criticized by those who support the "young canyon" age of around six million years as "[an] attempt to push the interpretation of their new data to their limits without consideration of the whole range of other geologic data sets." The canyon is the result of erosion which exposes one of the most complete geologic columns on the planet. The major geologic exposures in the Grand Canyon range in age from the 2-billion-year-old Vishnu Schist at the bottom of the Inner Gorge to the 270-million-year-old Kaibab Limestone on the Rim.
Grand Canyon | Geology
The river then turns due-south—running down the East Kaibab Monocline.
Grand Canyon Supergroup | Northeast Grand Canyon
This rock unit is made of coarse-grained sandstone, and was deposited in a shallow sea on top of the eroded surface of the Cardenas Basalt. The Nankoweap is only exposed in the eastern part of the canyon. A gap in the geologic record, an unconformity, follows the Nankoweap. All formations in the Chuar Group were deposited in coastal and shallow sea environments about 1000 to 700 million years ago. The Galeros Formation is a mainly greenish formation composed of interbedded sandstone, limestone, and shale. Fossilized stromatolites are found in the Galeros. The Kwagunt Formation consists of black shale and red to purple mudstone with some limestone.
Geology of the Grand Canyon area | Grand Canyon Supergroup
The geology of Westwater Canyon is very similar to nearby National Parks and Monuments such as Canyonlands National Park, Colorado National Monument, and Arches National Park. The uppermost rocks in the canyon date from the Triassic-Jurassic periods and are composed of the reddish, cliff-forming Wingate Sandstone atop the green to purple, slope-forming Chinle Formation. Within the inner gorge of Westwater, a large unconformity separates the Chinle Formation from the Precambrian basement rocks composed of metamorphic Vishnu Schist (black) and Zoroaster Granite (pink). Westwater Canyon and Ruby Canyon are the only places on the Colorado River outside of the Grand Canyon where Precambrian rocks are exposed.
Westwater Canyon | Geology
Sediments from surrounding mountains added weight to the basin, keeping it at relatively the same elevation. These sediments later lithified (turned to rock) to form the Toroweap Formation, now exposed in the Grand Canyon to the south but not in the Zion and Kolob area. This formation is not exposed in the park, though it does form its basement rock.
Geology of the Zion and Kolob canyons area | Grand Staircase and basement rocks
Canyon walls in this stretch rise above the sandy bed of the river. Other sights include large boulders, juniper trees, and Native American petroglyphs.
Dry River (Crooked River tributary) | Introduction
In 2012, Rocky Contos descended the entire river with various companions along the way.
Marañón River | The Grand Canyon of the Amazon
This formation consists of red siltstones and shale capped by tan-colored sandstone beds that together reach a thickness of 600 to 700 ft (around 200 m). Shale in the early Permian formations in this group were oxidized to a bright red color. Fossils of amphibian footprints, reptiles, and plentiful plant material are found in the eastern part and increasing numbers of marine fossils are found in the western part. Formations of the Supai Group are from oldest to youngest (an unconformity is present at the top of each): Watahomigi (see 5a in figure 1) is a slope-forming gray limestone with some red chert bands, sandstone, and purple siltstone that is thick.
Geology of the Grand Canyon area | Supai Group
The Uinkaret volcanic field is an area of monogenetic volcanoes in northwestern Arizona, United States, located on the north rim of the Grand Canyon. Lava flows from the Uinkaret volcanic field that have cascaded down into the Grand Canyon, damming the Colorado River, have been used to date the canyon's carving. One of these cascades is today's Lava Falls. Lava Falls Rapid, below Lava Falls on the Colorado River, is "at all water levels, the most severe rapid in Grand Canyon." The Colorado River was dammed by lava flows multiple times from 725,000 to 100,000 years ago. While some believe that these lava dams were stable, lasting up to 20,000 years and forming large reservoirs, others think they failed quickly and catastrophically as massive floods.
Uinkaret volcanic field | Introduction