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.
Introduction
Geology of the Grand Canyon area
Geology of the Grand Canyon area | Introduction
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. Sorry. I cannot find the answer based on the context. Sorry. I cannot find the answer based on the context. Sorry. I cannot find the answer based on the context.
are the oldest rocks in the world in the grand canyon
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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
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
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 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
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
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
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
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 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
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
The oldest rocks in Arizona likely date to the late Archean or early Proterozoic, although evidence of earlier geology was overwritten during the Yavapai orogeny and the Mazatzal orogeny—major mountain building events 1.8 to 1.6 billion years ago. During this period in the Proterozoic, the Yavapai, Pinal and Vishnu schist rocks formed due to intense metamorphism and were intruded with granites. These ancient deformed rocks are found at the base of the Grand Canyon, in Salt River Canyon, and in mountain ranges throughout the state. Arizona's oldest rocks overall are metamorphosed volcanic rocks, including basalt and rhyolite and related sedimentary rocks, that now constitute the bottom of the Grand Canyon and formed beginning 1.8 billion years ago.
Geology of Arizona | Precambrian: Before 541 million years ago
Any rocks that were deposited on top of the Grand Canyon Supergroup in the Precambrian were completely removed. This created a major unconformity that represents 460 million years of lost geologic history in the area.
Geology of the Grand Canyon area | Grand Canyon Supergroup
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
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
It is a slope-former and is thick. Glauconite is responsible for the green coloration of the Bright Angel. Muav Limestone averages 505 million years old and is made of gray, thin-bedded limestone that was deposited farther offshore from calcium carbonate precipitates (see 3c in figure 1). The western part of the canyon has a much thicker sequence of Muav than the eastern part. The Muav is a cliff-former, thick. These three formations were laid down over a period of 30 million years from early-to-middle Cambrian time. Trilobites followed by brachiopods are the most commonly reported fossils in this group but well-preserved fossils are relatively rare.
Geology of the Grand Canyon area | Tonto Group
At about 2.5 and 1.8 billion years ago in Precambrian time, sand, mud, silt, and ash were laid down in a marine basin adjacent to an orogenic belt. From 1.8 to 1.6 billion years ago at least two island arcs collided with the proto-North American continent. This process of plate tectonics compressed and grafted the marine sediments in the basin onto the mainland and uplifted them out of the sea. Later, these rocks were buried under the surface and pressure-cooked into metamorphic rock. The resulting Granite Gorge Metamorphic Suite, which is part of the Vishnu Basement Rocks, consists of the metasedimentary Vishnu Schist and the metavolcanic Brahma and Rama Schists that were formed 1.75 billion to 1.73 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
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
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
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
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
Isolated pockets of reddish sandstone are also found around Carbon Butte. Stromatolites are found in this layer. The Sixtymile Formation is made of tan-colored sandstone with some small sections of shale. About 800 million years ago the supergroup was tilted 15° and block faulted in the Grand Canyon Orogeny. Some of the block units moved down and others moved up while fault movement created north–south-trending fault-block mountain ranges. About 100 million years of erosion took place that washed most of the Chuar Group away along with part of the Unkar Group (exposing the Shinumo Quartzite as previously explained). The mountain ranges were reduced to hills, and in some places, the whole of the supergroup were removed entirely, exposing the basement rocks below.
Geology of the Grand Canyon area | Grand Canyon Supergroup
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
The rocks exposed in Bryce Canyon are about 100 million years younger than those in nearby Zion National Park, and the rocks exposed in Zion are younger than those in the Grand Canyon to the south. There are, however, shared rock units between all three, creating a supersequence of formations that geologists call the Grand Staircase. Together the formations of the Grand Staircase record nearly 2000 million years of the Earth's history. 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.
Geology of the Bryce Canyon area | Grand Staircase
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
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
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
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
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
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
The park's oldest rocks, Pinto gneiss among them, are 1.7 billion years old. They are exposed in places on the park's surface in the Cottonwood, Pinto, and Eagle Mountains. Much later, from 250 to 75 million years ago, tectonic plate movements forced volcanic material toward the surface at this location and formed granites, including monzogranite common to the Wonderland of Rocks, parts of the Pinto, Eagle, and Coxcomb Mountains, and elsewhere. Erosion eventually exposed the harder rocks, gneiss and granite, in the uplands and reduced the softer rocks to debris that filled the canyons and basins between the ranges. The debris, moved by gravity and water, formed alluvial fans at the mouths of canyons, and "bajadas", where the alluvial fans overlapped.
Joshua Tree National Park | Geology
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
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
Perhaps 3 billion years ago in Precambrian time, sand, limey ooze, silt and clay were deposited in a marine trough (accurate dating is not possible, due to subsequent partial recrystallization of the resulting rock). Between these layers were volcanic deposits, probably from an island arc. These sediments were later lithified into sandstones, limestones, and various shales. These rocks were 5 to 10 miles (8 to 16 km) below the surface when orogenies (mountain-building episodes) around 2.8 to 2.7 billion years ago intensely folded and metamorphosed them, creating alternating light and dark banded gneiss and schist. Today these rocks dominate the east side of the Teton Range with good examples easily viewable in Death Canyon and other canyons.
Geology of the Grand Teton area | Precambrian deposition, metamorphism, and intrusion
The third phase was accompanied by large-scale faulting, particularly along north–south faults, leading to a partial rifting of the continent. The collision expanded the continent from the Wyoming–Colorado border into Mexico and almost doubled the crust's thickness in the Grand Canyon region. Part of this thickening created the high ancestral Mazatzal Mountains. Subsequent erosion lasting 300 million years stripped much of the exposed sediments and the mountains away. This reduced the very high mountains to small hills a few tens to hundreds of feet (tens of meters) high. Geologist John Wesley Powell called this major gap in the geologic record, which is also seen in other parts of the world, the Great Unconformity.
Geology of the Grand Canyon area | Vishnu Basement Rocks
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
The geology of the Grand Teton area consists of some of the oldest rocks and one of the youngest mountain ranges in North America. The Teton Range, partly located in Grand Teton National Park, started to grow some 9 million years ago. An older feature, Jackson Hole, is a basin that sits aside the range. The 2.5 billion year old metamorphic rocks that make up the east face of the Tetons are marine in origin and include some volcanic deposits. These same rocks are today buried deep inside Jackson Hole. Paleozoic rocks were deposited in warm shallow seas while Mesozoic deposition transitioned back and forth from marine to non-marine sediments with the Cretaceous Seaway periodically covering the area late in that era.
Geology of the Grand Teton area | Introduction
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
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
This formation only exists in isolated lenses that are thick. Surprise Canyon was unknown to science until 1973 and can be reached only by helicopter. Fossil logs, other plant material and marine shells are found in this formation. An unconformity marks the top of the Surprise Canyon Formation and in most places this unconformity has entirely removed the Surprise Canyon and exposed the underlying Redwall.
Geology of the Grand Canyon area | Temple Butte, Redwall, and Surprise Canyon
The northern part of the Monument in part has gently sloping, relatively even surfaces ranging in elevation from about in the east to about in the west. These surfaces are upheld by sedimentary rocks of Cretaceous age that are mostly covered by much younger gravel and sand layers deposited in the last several million years. The region is incised by canyons that drain south and west to McElmo Creek; the creek falls from the east at about west at the Utah border. The oldest rocks are exposed in McElmo Canyon and are sedimentary layers of Jurassic age. In and near the Monument, these sedimentary rocks have been bent upwards to form a dome, the McElmo Dome: most of the Jurassic rocks are below the surface in the regions immediately bordering the area.
Canyons of the Ancients National Monument | Geology and topography
The uplift caused the formation of vertical joints which were later preferentially eroded to form the free-standing pinnacles called hoodoos, badlands, and monoliths we see today. The formations exposed in the area of the park are part of the Grand Staircase. The oldest members of this supersequence of rock units are exposed in the Grand Canyon, the intermediate ones in Zion National Park, and its youngest parts are laid bare in Bryce Canyon area. A small amount of overlap occurs in and around each park.
Geology of the Bryce Canyon area | Introduction
The youngest rocks exposed in the canyon are a series of basalt lava flows that form the east rim, the youngest of which is an estimated 6 million years old.
Oak Creek Canyon | Geology
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
Current archaeological evidence suggests that humans inhabited the Grand Canyon area as far back as 4,000 years ago and at least were passers-through for 6,500 years before that. Radiocarbon dating of artifacts found in limestone caves in the inner canyon indicate ages of 3,000 to 4,000 years. In the 1950s split-twig animal figurines were found in the Redwall Limestone cliffs of the Inner Gorge that were dated in this range. These animal figurines are a few inches (7 to 8 cm) in height and made primarily from twigs of willow or cottonwood. This and other evidence suggests that these inner canyon dwellers were part of Desert Culture; a group of semi-nomadic hunter-gatherer Native American.
History of the Grand Canyon area | Early history
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
Other sediments may have been added but, if they ever existed, were completely removed by erosion. Such gaps in the geologic record are called unconformities by geologists. The Great Unconformity is one of the best examples of an exposed nonconformity, which is a type of unconformity that has bedded rock units above igneous or metamorphic rocks.
Geology of the Grand Canyon area | Vishnu Basement Rocks
The Precambrian and Paleozoic history of the Colorado Plateau is best revealed near its southern end where the Grand Canyon has exposed rocks with ages that span almost 2 billion years. The oldest rocks at river level are igneous and metamorphic and have been lumped together as Vishnu Basement Rocks; the oldest ages recorded by these rocks fall in the range 1950 to 1680 million years. An erosion surface on the "Vishnu Basement Rocks" is covered by sedimentary rocks and basalt flows, and these rocks formed in the interval from about 1250 to 750 million years ago: in turn, they were uplifted and split into a range of fault-block mountains.
Colorado Plateau | Geology
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
The exposed geology of the Canyonlands area is complex and diverse; 12 formations are exposed in Canyonlands National Park that range in age from Pennsylvanian to Cretaceous. The oldest and perhaps most interesting was created from evaporites deposited from evaporating seawater. Various fossil-rich limestones, sandstones, and shales were deposited by advancing and retreating warm shallow seas through much of the remaining Paleozoic. Eroded sediment from a nearby mountain range later mixed with coastal dune and sand bar deposits. The end of the Paleozoic and the start of the Mesozoic saw the last seas start to leave the region for good.
Geology of the Canyonlands area | Introduction
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
Saguaro National Park's oldest rocks, the Pinal Schist, pre-date the formation of the contemporary Basin and Range Province, of which the park is a part, by about 1.7 billion years. The schist is exposed in the Rincon Mountain District along a dry wash off Cactus Forest Loop Drive. Other ancient rocks, 1.4-billion-year-old altered granites, form much of Tanque Verde Ridge in the Rincon Mountain District. Much later, about 600 million years ago, shallow seas covered the region around present-day Tucson; over time that led to deposition of sedimentary rocks—limestones, sandstones, and shales. Limestone, which occurs in the park in several places, was mined here in the late 19th century to make mortar.
Saguaro National Park | Geology
Grand Teton National Park has some of the most ancient rocks found in any American national park. The oldest rocks dated so far are 2,680 ± 12 million years old, though even older rocks are believed to exist in the park. Formed during the Archean Eon (4 to 2.5 billion years ago), these metamorphic rocks include gneiss, schist and amphibolites. Metamorphic rocks are the most common types found in the northern and southern sections of the Teton Range. 2,545 million years ago, the metamorphic rocks were intruded by igneous granitic rocks, which are now visible in the central Tetons including Grand Teton and the nearby peaks.
Grand Teton National Park | Geology
At 2.7 billion years old, they are older than the rocks in the bottom of the Grand Canyon. Tintic Quartzite is found on the northern third of the island. It is about 550 million years old. Tufa rocks on the island are some of the youngest rocks in the United States. They were deposited as Lake Bonneville receded between 10,000 - 15,000 years ago. The tufa rocks resemble concrete and are in the vicinity of Buffalo Point.
Antelope Island | 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 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
The Red Rock area has a complex geological history, which over millions of years, helped create the region's dramatic landscape. The Red Rock area was under an ocean basin during the Paleozoic Era 600 million years ago. Up to of limey sediments were deposited and eventually lithified to limestone. During the Mesozoic Era 250 million years ago, the earth's crust started to rise due to tectonic shifts, and marine shales and sandstones were deposited. As the basin became isolated evaporite formations of salt and gypsum were deposited. Oxidation of the iron minerals in the sediments resulted in the red colors of some of the rocks.
Red Rock Canyon National Conservation Area | Geology
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
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 late Mississippian time, the Grand Canyon region was slowly uplifted and the Redwall was partly eroded away. A Karst topography consisting of caves, sinkholes, and subterranean river channels resulted but were later filled with more limestone. The exposed surface of Redwall gets its characteristic color from rainwater dripping from the iron-rich redbeds of the Supai and Hermit shale that lie above. Surprise Canyon Formation is a sedimentary layer of purplish-red shale that was laid down in discontinuous beds of sand and lime above the Redwall (see 4c in figure 1). It was created in very late Mississippian and possibly in very earliest Pennsylvanian time as the land subsided and tidal estuaries filled river valleys with sediment.
Geology of the Grand Canyon area | Temple Butte, Redwall, and Surprise Canyon
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 preserve houses some of the oldest exposed rocks in California, dated at almost two billion years. They consist of granite that has been altered by centuries of heat and pressure to form gneiss and schist. The preserve is characterized by steep canyons, rugged terrain and desert oases. The upstream end of the canyon originates in the Mojave Desert, while its downstream portion opens into the Colorado Desert. The Morongo fault running through the canyon causes water draining from the surrounding mountains to form Big Morongo Creek and the marsh habitat.
Big Morongo Canyon Preserve | Geography
Sandstone is the youngest stone represented in the gorge. It formed during the Lower Permian and is therefore about 250 million years old. During this period, which had a desert climate characterized by large temperature differences between day and night and little precipitation, large rocks under the influence of weather conditions disintegrated into small pieces or sand. However, when this area was flooded by the shallow sea, these particles, together with silt and clay, were consolidated into new rock.
Dovžan Gorge | Sandstone
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
Most of the basal part of the Mesozoic sequence consists of the more than thick, soft, bright-red, and Triassic-aged rocks known as the Chugwater Formation. The distribution of Mud cracks, fossilized reptiles and amphibians suggest deposition in a tidal flat environment with a sea several kilometers southwest of Jackson Hole. Evaporite deposits of a few beds of white gypsum (calcium sulfate) were likely formed after shallow bodies of salt water were cut off from the sea. A small amount of iron oxide creates the red color and the formation erodes into colorful hills east and south of the park. As the Triassic gave way to the Jurassic, wind spread salmon-red colored sand across the red beds of the Chugwater Formation to form the Nugget Sandstone.
Geology of the Grand Teton area | Sundance Sea covers older deposits
Deposition by streams and in swamp environments resulted in the formation of petrified wood in the area. By 180 million years ago, the climate continued to change and the area became a desert with vast expanses of huge shifting sand dunes. These dunes accumulated over a broad area, up to thick, and were lithified, cemented with calcium carbonate and iron oxides. They developed as the colorful Aztec Sandstone.
Red Rock Canyon National Conservation Area | Geology
The following description of the geology of the Monument is derived mostly from contributions to Anderson et al. (1997), unless otherwise referenced. The nomenclature of the rock units here may not represent the present consensus. The sedimentary sequence is over thick and is represented by the stratigraphic units listed below.
Canyons of the Ancients National Monument | Formations from the Cretaceous and Jurassic periods
The Surprise Canyon Formation is found extensively in regions below Grand Canyon Village, Arizona, South Rim, regions northwest, north, and northeast. It is discontinuous, but is found in geologic sequences below the South Rim, and its various landforms, and also especially at the Inner Gorge in specific landforms that have cliffs, and upper surface platforms of the Redwall Limestone. Example landforms near Grand Canyon Village, are Pattie Butte-(Newton Butte), Tower of Set, (due west of Isis Temple), and Brahma Temple's southern Redwall Limestone points, Johnson and Sturdevant Points, due east of Isis Temple. Fossils of plant material, marine shells, where some fossils may have been 'derived fossils' from the Redwall Limestone, are found in the formation; also fossil logs, showing the erosion, or valley and canyon topographies and the erosional forces of the time period.
Surprise Canyon Formation | Introduction
Most of the mountains and canyons in the Sierra Nevada are composed of granitic rocks. These rocks, such as granite, diorite and monzonite, formed when molten rock cooled far beneath the surface of the earth. The molten rock was the result of a geologic process known as subduction. Powerful forces in the earth forced the landmass under the waters of the Pacific Ocean beneath and below an advancing North American Continent. Super-hot water driven from the subducting ocean floor migrated upward and melted rock as it proceeded. This process took place during the Cretaceous Period, 100 million years ago. Granitic rocks have a speckled salt-and-pepper appearance because they contain various minerals including quartz, feldspars and micas.
Sequoia National Park | Geology
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
Although the Grapevine Mountains were uplifted relatively recently, most of the rocks that make up the range are over half a billion years old. The gray rocks lining the walls of the western end of Titus Canyon are Cambrian age (570–505 million years old) limestone. These ancient Paleozoic rocks formed at a time when the Death Valley area was submerged beneath tropical seas. By the end of the Precambrian, the continental edge of North America had been planed off by erosion to a gently rounded surface of low relief. The rise and fall of the Cambrian seas periodically shifted the shoreline eastward, flooding the continent, then regressed westward, exposing the limestone layers to erosion.
Titus Canyon | Geology
The mesa is topped by a hard volcanic basalt. This layer, formed approximately 10 million years ago by basalt flows, suppressed erosion compared to the surrounding sedimentary rock layers, which suffered rapid downcutting from the action of the Colorado and the Gunnison rivers. The top layer rests on a thick sequence of Eocene shale and sandstone known as the Green River and Wasatch Formations. These layers in turn rest on a Cretaceous layer known as the Mesaverde Group that forms a cliff about halfway up the side of the mesa. The lowest layers are yellow and gray Mancos Shale of late Cretaceous age.
Grand Mesa | 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
The light colored granites of the central Teton Range contrast with the darker metamorphic gneiss found on the flanks of Mount Moran to the north. Magma intrusions of diabase rocks 765 million years ago left dikes that can be seen on the east face of Mount Moran and Middle Teton. Granite and pegmatite intrusions also worked their way into fissures in the older gneiss. Precambrian rocks in Jackson Hole are buried deep under comparatively recent Tertiary volcanic and sedimentary deposits, as well as Pleistocene glacial deposits. By the close of the Precambrian, the region was intermittently submerged under shallow seas, and for 500 million years various types of sedimentary rocks were formed.
Grand Teton National Park | Geology
Younger rock units were laid down but were mostly removed by subsequent uplift-accelerated erosion. Outcrops of these formations can be found in the northern part of the park and in a few places on the plateau rim. Among these are the thick Oligocene or Miocene-aged Boat Mesa Conglomerate and the Pliocene to early Pleistocene-aged Sevier River Formation. The Boat Mesa is made mostly of conglomerates with minor amounts of sandstone and some limestone from lakes, representing stream and overbank flood deposits. The brownish-gray sandstone and gravels of the Sevier River Formation were laid down in valleys that were part of the ancestral Sevier River drainage system.
Geology of the Bryce Canyon area | Formation of the High Plateaus
At Pine, on Arizona State Route 87, at the northeast region of the Mazatzal Wilderness, north terminus of the Mazatzal Mountains, the route traverses the contact between two important geologic units. The horizontally laid Tapeats Sandstone, (common areal extent in Grand Canyon), was deposited on Precambrian granite, the Zoroaster Granite. The time between the erosion of the lower unit and deposition of the horizontal sandstone above, is about 1 billion years-(1,000 million years), and is named the Great Unconformity. Besides its occurrence in the Grand Canyon, it is also found west, in the Las Vegas Valley, at Frenchman Mountain. The Zoroaster Granite and other granites, were intruded into the major unit of the Vishnu Schist, the basement paleo unit found in the Inner Gorge region of the Grand Canyon.
Mazatzal Mountains | Great Unconformity, Mazatzal Wilderness region
Alternating layers of nonmarine, intertidal, and marine sediments lay on top of each other as a result. Conglomerate, siltstone, and fossil-rich sandstone that together are up to thick mark the arrival of the Cretaceous Seaway. Called the Dakota Sandstone, it is the oldest formation exposed in the Bryce Canyon area but the youngest one exposed in the Zion and Kolob canyons area to the southwest. Abundant amounts of petrified wood, oyster beds containing millions of fossils, and coal are all found in the Dakota. In the Bryce Canyon area, this formation can be seen in the Paria Valley where it is found as a lithified blanket sand that probably accumulated on beaches, in lagoons, and vast coal-producing swamps as the Cretaceous Seaway transgressed (advanced inland) over the region and later retreated.
Geology of the Bryce Canyon area | Advance
the Cretaceous and Jurassic periods). The bedrock of the lower slopes of the canyon - largely hidden under slope debris/ravine fill - is pillow lava or greenstone; these erupted from fissures in the deep ocean floor when the terrane was located hundreds of miles southwest of its present location. The upper slopes and cliffs are of layered chert, which hardened into rock from the ooze of remains of countless radiolarian creatures that accumulated on top of the lava. The ooze was colored red by iron from hydrothermal springs. Both lava and chert were formed in the deep ocean near the equator, and were rafted northeast on the gradually-moving ocean floor toward California.
Glen Canyon Park | Geology and rock outcrops
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
The Great Unconformity of Powell in the Grand Canyon is a regional unconformity that separates the Tonto Group from the underlying, faulted and tilted sedimentary rocks of the Grand Canyon Supergroup and vertically foliated metamorphic and igneous rocks of the Vishnu Basement Rocks. The unconformity between the Tonto Group and the Vishnu Basement Rocks is a nonconformity. The break between the Tonto Group and the Grand Canyon Supergroup is an angular unconformity. Powell's Great Unconformity is part of a continent-wide unconformity that extends across Laurentia, the ancient core of North America. It was first recognized twelve years before Powell's expedition by John Newberry in New Mexico, during the Ives expedition of 1857-1858.
Great Unconformity | Powell’s Unconformity, Grand Canyon
The eastern Uinta Mountains near the Colorado line and the Raft River-Dover Creek Mountains contain the oldest rocks in Utah from more than two billion years ago. Rubidium-strontium dating of the Red Creek Quartzite in 1965 indicated an age of 2.3 billion years. Other geologists found 2.4 billion year old schist and gneiss in the Albion Range Green Creek Complex. Prior to the 1960s, geologists inferred the Vishnu and Farmington Canyon gneiss and schist as Archean in age, but subsequent research indicated an formation between 1.6 and 1.5 billion years ago in the Proterozoic. From 1.75 to 1.65 billion years ago, Utah was impacted by the Matzatzal Orogeny.
Geology of Utah | Geologic History, Stratigraphy & Tectonics
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
Erosion greatly reduced this mountain range prior to the encroachment of a seaway along the passive western edge of the continent in the early Paleozoic. At the canyon rim is the Kaibab Formation, limestone deposited in the late Paleozoic (Permian) about 270 million years ago. A extension of the Ancestral Rocky Mountains called the Uncompahgre Mountains were uplifted and the adjacent Paradox Basin subsided. Almost 4 mi. (6.4 km) of sediment from the mountains and evaporites from the sea were deposited (see geology of the Canyonlands area for detail). Most of the formations were deposited in warm shallow seas and near-shore environments (such as beaches and swamps) as the seashore repeatedly advanced and retreated over the edge of a proto-North America (for detail, see geology of the Grand Canyon area).
Colorado Plateau | Geology
The exposed geology of the Bryce Canyon area in Utah shows a record of deposition that covers the last part of the Cretaceous Period and the first half of the Cenozoic era in that part of North America. The ancient depositional environment of the region around what is now Bryce Canyon National Park varied from the warm shallow sea (called the Cretaceous Seaway) in which the Dakota Sandstone and the Tropic Shale were deposited to the cool streams and lakes that contributed sediment to the colorful Claron Formation that dominates the park's amphitheaters. Other formations were also formed but were mostly eroded following uplift from the Laramide orogeny which started around 70 million years ago (mya).
Geology of the Bryce Canyon area | Introduction
Volcanic activity in the Marysvale and Bryce area ceased some 500,000 years ago. Basaltic rocks of the same age can be seen along the Sevier Fault near the entrance to Red Canyon; the dark colored volcanic rocks have been displaced by the fault some and are now in direct contact with the much older Claron Formation.
Geology of the Bryce Canyon area | Marysvale volcanics
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
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
As the shoreline continued to move eastward, the 285-foot-thick (87 m) Death Canyon Limestone Member of the Gros Ventre Formation was laid down in clear water farther from shore. It consists of two thick beds of dark blue-gray limestone that are separated by 15 to 20 feet (4.5 to 6 m) of shale. The Death Canyon contains abundant fossil of brachiopods and trilobites in some places. Following this the sea retreated to the west for a short time. The 220-foot-thick (67 m) Park Shale Member of the Gros Ventre Formation was deposited in the shallow muddy water resulting from this retreat.
Geology of the Grand Teton area | Covered by a shallow sea
The Grand Canyon Supergroup is a Mesoproterozoic to Neoproterozoic sequence of sedimentary strata, mostly exposed in the eastern Grand Canyon of Arizona. This group is composed of the Unkar Group, Nankoweap Formation, Chuar Group and the Sixtymile Formation, which overlie Vishnu Basement Rocks. Several notable landmarks of the Grand Canyon, such as the "Isis Temple and Cheops Pyramid" and the "Apollo Temple," are surface manifestations of the Grand Canyon Supergroup.
Grand Canyon Supergroup | Introduction
The green to black serpentine created was used by Native Americans to make bowls. Sometime around 2.5 billion years ago, blobs of magma intruded into the older rock, forming plutons of granitic rock. Extensive exposures of this rock are found in the central part of the range. About 1.3 to 1.4 billion years ago in Late Precambrian, 5 to 200 foot (1.5 to 60 m) thick black diabase dikes intruded as well, forming the prominent vertical dikes seen today on the faces of Mount Moran and Middle Teton (the dike on Mount Moran is ). Some of the large dikes can be seen from the Jenny Lake and String Lake areas.
Geology of the Grand Teton area | Precambrian deposition, metamorphism, and intrusion
The canyon is part of the Canadian Shield, a fundamental rock formation of northern parts of Manitoba, Ontario and Quebec, all around the Hudson Bay. It all started in the Precambrian Age (1,2 billion years ago) when hard rock formed the canyon's underlying rock. This metamorphic rock, called granitic gneiss, was formed at high pressure in the extremely hot depths of earth then rose to the surface through erosional uplift. It comprises much of Mount St. Anne. Later, some 450 million years ago, a sedimentary Palaeozoic sediment, a marine mud, was deposited in ancient seas on top of the gneiss, and consolidated into a rock called shale.
Canyon Sainte-Anne | Geology
This geological formation is an eroded fin composed of Cedar Mesa Sandstone, which is the remains of coastal sand dunes deposited about 245–286 million years ago, during the early Permian period. The top of the formation rises 450 feet above the canyon floor, and two keyhole openings have a height of 85 feet, and a width of 20 feet.
Druid Arch | Geology
The park's geologic record preserves three different groups of rock and sediment. The oldest rocks are Early to Middle Proterozoic gneiss and schist, including the Ute Canyon Stock. Overlying these, and separated by an angular unconformity, are mostly horizontally bedded Mesozoic sedimentary rocks, including the cliff-forming Wingate Sandstone. Overlying these are various types of Quaternary unconsolidated deposits such as alluvium, colluvium, and dunes. The sedimentary rocks are folded into monoclines by several faults, including the Redlands Thrust Fault.
Colorado National Monument | Geology
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
Within the Grand Canyon, the Great Unconformity represents a period of about 175 million years between the Tonto Group and the youngest subdivision, the Sixtymile Formation, of the Grand Canyon Supergroup. At the base of the Grand Canyon Supergroup, where it truncates the Bass Formation, the period of time represented by this angular unconformity increases to about 725 million years. Where the Tonto Group overlies the Vishnu Basement Rocks, the Great Unconformity represents a period as much as 1.2 to 1.6 billion years. (See also geological timescale.)
Great Unconformity | Powell’s Unconformity, Grand Canyon
The spectacularly eroded walls of the canyon are formed mostly of Paleozoic sedimentary rocks. Exposures of the Kaibab Limestone, (the geologic formation found at the top of the Grand Canyon), and the Toroweap Formation are found only at the northern end of the canyon. The more predominant rock units exposed in the cliffs of southern Oak Creek Canyon are the buff to white colored, frequently cross-bedded Permian Coconino Sandstone and the red sandstones of the Permian Schnebly Hill Formation. Unlike all the other formations exposed in Oak Creek Canyon, the Schnebly Hill Formation is not present at the Grand Canyon.
Oak Creek Canyon | Geology
The Grand Canyon is a river valley in the Colorado Plateau that exposes uplifted Proterozoic and Paleozoic strata, and is also one of the six distinct physiographic sections of the Colorado Plateau province. Even though It is not the deepest canyon in the world (Kali Gandaki Gorge in Nepal is much deeper), the Grand Canyon is known for its visually overwhelming size and its intricate and colorful landscape. Geologically, it is significant because of the thick sequence of ancient rocks that are well preserved and exposed in the walls of the canyon. These rock layers record much of the early geologic history of the North American continent.
Grand Canyon | Geography
Early in the Permian a transgressing (advancing) sea laid down the Halgaito Shale. Coastal lowlands returned to the area after the sea regressed (retreated), forming the Elephant Canyon Formation. These formations can now be seen in Cataract and Elephant Canyons. The Uncompahgre Mountains (Uncompahgre Plateau) were undergoing extensive erosion during this time. Large alluvial fans filled the basin where it met the range. The resulting Cutler red beds are made of iron-rich arkose sandstone. Underwater sand bars and sand dunes on the coast inter-fingered with the red beds and later became the white-colored cliff-forming Cedar Mesa Sandstone. Today these two competing rock units are exposed in a 4 to 5 mile (6.4 to 8 km) wide belt across the park, stretching from south of the Needles through the Maze and to the Elaterite Basin.
Geology of the Canyonlands area | Cutler Group
Over 40 million years ago an ocean covered San Clemente Canyon during the Eocene epoch of the Paleogene period. Horizontal lines of round rocks at many levels, separated by clay and sand, represent the various levels of the ocean washing sand away and leaving rocks at surf level. Fossilized mollusks, such as snails and clams from that period are still found in the canyon's walls. The fossils are preserved in the sandstones and siltstones of the Scripps Formation that is best exposed in the roadcuts along Regents Road and Genesee Avenue.
San Clemente Canyon | Canyon geology
The Glen Canyon Group of formations includes (from oldest - lowest - to youngest) the These formations are most prominently exposed in the western and northern sections of the park. Triassic climates progressively became dryer, prompting the formation of sand dunes that buried dry stream beds and their flood plain. This sand became the cliff-forming several hundred feet (many tens of meters) high and red-colored Windgate Sandstone. Outcrops tend to run for hundreds of miles (hundreds of kilometers) with few breaks, creating an impediment to human travel. For a time climatic conditions became wetter and streams cut channels through the sand dunes.
Geology of the Canyonlands area | Glen Canyon Group