The Grand Canyon from Navajo Point. The Colorado River is to the right and the North Rim can be seen to the left in the distance. Also visible is nearly every sedimentary layer described in this article.

The geology of the Grand Canyon area exposes one of the most complete sequences of rock anywhere, representing a period of nearly 2 billion years of the Earth's history in that part of North America. The major sedimentary rock layers exposed in the Grand Canyon and in the Grand Canyon National Park area range in age from 200 million to nearly 2 billion years old. Most were deposited in warm, shallow seas and near ancient, long-gone sea shores. Both marine and terrestrial sediments are represented, including fossilized sand dunes from an extinct desert. Download high resolution version (1200x443, 102 KB)Image of the Grand Canyon from Navajo Point taken on April 9, 2004 by Daniel Mayer. ... Download high resolution version (1200x443, 102 KB)Image of the Grand Canyon from Navajo Point taken on April 9, 2004 by Daniel Mayer. ... The rocky side of a mountain creek near Orosí, Costa Rica. ... Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ... World map showing North America A satellite composite image of North America. ... Two types of sedimentary rock: limey shale overlaid by limestone. ... The Grand Canyon is a very colorful, steep-sided gorge, carved by the Colorado River, in the U.S. state of Arizona. ... Grand Canyon National Park is one of Americas oldest national parks and is located in Arizona. ... Sea as seen from jetty in Frankston, Australia Look up maritime in Wiktionary, the free dictionary. ... This article is about the sand formations, for other meanings see Dune (disambiguation) Mesquite Flat Dunes in Death Valley National Park In physical geography, a dune is a hill of sand built by eolian (wind-related) processes. ... Erg Chebbi, Morocco In geography, a desert is a landscape form or region that receives very little precipitation. ...

Uplift of the region started about 75 million years ago in the Laramide orogeny, a mountain-building event that is largely responsible for creating the Rocky Mountains to the east. Accelerated uplift started 17 million years ago when the Colorado Plateaus (on which the area is located) were being formed. In total these layers were uplifted an estimated 10,000 feet (3000 m) which enabled the ancestral Colorado River to cut its channel into the four plateaus that constitute this area. But the canyon did not start to form until 5.3 million years ago when the Gulf of California opened up and thus lowered the river's base level (its lowest point) from that of large inland lakes to sea level. The Laramide orogeny was a period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. ... Lyskamm, 4 527 m, Pennine Alps A mountain is a landform that extends above the surrounding terrain in a limited area. ... Moraine Lake, and the Valley of the Ten Peaks, Banff National Park, Alberta, Canada The Rocky Mountains, often called the Rockies, are a broad mountain range in western North America. ... The Colorado Plateau, also called the Colorado Plateaus Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. ... Colorado River in the Grand Canyon from Desert View The Colorado River is a river in the southwestern United States and northwestern Mexico, approximately 1,450 mi (2,333 km) long, draining a part of the arid regions on the western slope of the Rocky Mountains. ... Grand Canyon, Arizona A canyon or gorge is a deep valley between cliffs often carved from the Earth by a river. ... The Gulf of California (also known as the Sea of Cortez or Sea of Cortés; locally known in the Spanish language as Mar de Cortés or, much less frequently, Golfo de California) is a body of water that separates the Baja California Peninsula from the Mexican mainland. ... The base level of a river or stream is the lowest point to which it can flow, often referred to as the mouth of the river. ... For considerations of sea level change, in particular rise associated with possible global warming, see sea level rise. ...

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 by 1.2 million years ago. Also about 2 million years ago volcanic activity started to deposit ash and lava over the area. At least 13 large lava flows dammed the Colorado River, forming huge lakes that were up to 2000 feet (600 m) deep and 100 miles (160 km) long. The nearly 40 identified rock layers and 14 major unconformities (gaps in the geologic record) of the Grand Canyon form one of the most studied sequences of rock in the world. Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ... Volcano 1. ... Ash plume from Mt Cleveland, a stratovolcano Diamond Head, a well-known backdrop to Waikiki in Hawaii, is an ash cone that solidified into tuff Volcanic ash consists of very fine rock and mineral particles less than 2 mm in diameter that are ejected from a volcanic vent. ... Look up lava, Aa, pahoehoe in Wiktionary, the free dictionary. ... There is a billion year gap in the geologic record where this 500 million year old dolomite unconformably overlays 1. ...

Figure 1. A geologic cross section of the Grand Canyon. Black numbers correspond to subsection numbers in section 1 and white numbers are referred to in the text

Download high resolution version (600x836, 67 KB)Photo of a display in the Grand Canyon visitors center. ... Download high resolution version (600x836, 67 KB)Photo of a display in the Grand Canyon visitors center. ...

Deposition of sediments

Some important terms: A geologic formation is a rock unit that has one or more sediment beds, and a member is a minor unit in a formation. Groups are sets of formations that are related in significant ways, and a supergroup is a sequence of vertically related groups and lone formations. The various kinds of unconformities are gaps in the geologic record. Such gaps can be due to an absence of deposition or due to subsequent erosion removing the rock units. A geologic formation is a formally named rock stratum or geological unit. ... Two types of sedimentary rock: limey shale overlaid by limestone. ... Interstate road cut through limestone and shale strata in eastern Tennessee In geology and related fields, a stratum (plural: strata) is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers. ... Interstate road cut through limestone and shale strata in eastern Tennessee In geology and related fields, a stratum (plural: strata) is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers. ... Interstate road cut through limestone and shale strata in eastern Tennessee In geology and related fields, a stratum (plural: strata) is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers. ... // For other uses, see time scale. ...

Vishnu Group

The Vishnu Group had its beginnings about 2 billion years ago in Precambrian time when thousands of feet of ash, mud, sand, and silt were laid down in a shallow forearc basin similar to the modern Sea of Japan. During this time period the basin was between Laurentia (proto-North America/Europe) and an orogenic belt of mountains and volcanoes in an island arc not unlike today's Japan. From 1.8 to 1.6 billion years ago the Yavapai and then the Mojave island arcs collided and accreted with the Wyoming craton of the proto-North American continent. This process of plate tectonics compressed and accreted marine sediments onto Laurentia. Essentially the island arcs slammed into the growing continent and the marine sediments in-between were squeezed together and uplifted out of the sea. The Precambrian (or Pre-Cambrian) is an informal name for the eons of the geologic timescale that came before the current Phanerozoic eon. ... Ash plume from Mt Cleveland, a stratovolcano Diamond Head, a well-known backdrop to Waikiki in Hawaii, is an ash cone that solidified into tuff Volcanic ash consists of very fine rock and mineral particles less than 2 mm in diameter that are ejected from a volcanic vent. ... In computer gaming, a MUD (Multi-User Dungeon or Domain or Dimension) is a multi-player computer game that combines elements of role-playing games, hack and slash style computer games and social chat rooms. ... Patterns in the sand Sand is a granular material made up of fine rock particles. ... Silt is soil or rock derived granular material of a specific grain size. ... The Sea of Japan (East Sea) is a marginal sea of the western Pacific Ocean. ... North American craton. ... World map showing North America A satellite composite image of North America. ... Europe at its furthest extent, reaching to the Urals. ... In geology, orogeny is the process of mountain building. ... Lyskamm, 4 527 m, Pennine Alps A mountain is a landform that extends above the surrounding terrain in a limited area. ... Volcano 1. ... An island arc is a type of archipelago formed by plate tectonics as one oceanic tectonic plate subducts under another and produces magma. ... World geologic provinces. ... Color-coded regions of the world based on the seven commonly-recognised continents Dymaxion map by Buckminster Fuller shows land masses with minimal distortion as nearly one continuous continent A continent is one of several large areas of land on Earth, which are identified by convention rather than any strict... Bridge across the Álfagjá rift valley in southwest Iceland, the boundary of the Eurasian and North American continental tectonic plates. ...

This is the metamorphic rock now exposed at the bottom of the canyon in the Inner Gorge. Geologists call this dark-colored, garnet-studded layer the Vishnu Schist. Combined with the other schists of this period, the Brahma and the Rama, this makes up the Vishnu Group (see 1a in figure 1). No identifiable fossils have been found in these strata, but lenses of marble now seen in these units were likely derived from colonies of primitive algae.^[1] Quartzite, a form of metamorphic rock, from the Museum of Geology at University of Tartu collection. ... Garnet is a group of minerals that have been used since the Bronze Age as gemstones and abrasives. ... Schist The schists form a group of medium-grade metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite, and others. ... Download high resolution version (600x836, 67 KB)Photo of a display in the Grand Canyon visitors center. ... Three small ammonite fossils, each approximately 1. ... Goldenville Strata exposed at a quarry in Bedford, Canada. ... Venus de Milo, front. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ...

The Vishnu Group was intruded by blobs of magma rising from a subduction zone offshore as recently as 1.66 billion years ago. These plutons slowly cooled to form the Zoroaster Granite (seen as light-colored bands in the darker Vishnu Schist; see 1b in Figure 1). Some of this rock eventually was metamorphosed into gneiss. The intrusion of the granite occurred in three phases: two during the initial Vishnu metamorphism period, and a third around 1.5 billion years ago. This third phase was accompanied by large-scale geologic faulting, particularly along north-south faults that caused some rifting, and a possible partial breakup of the continent..^[2] Magma is molten rock located beneath the surface of the Earth (or any other rocky planet), and which often collects in a magma chamber. ... The Juan de Fuca plate sinks below the North America plate at the Cascadia subduction zone. ... Devils Tower, an igneous intrusion exposed when the surrounding softer rock eroded away. ... Quarrying granite for the Mormon Temple, Utah Territory. ... Gneiss Gneiss (IPA: ) is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from preexisting formations that were originally either igneous or sedimentary rocks. ... Fault in metamorphosed strata near Adelaide, Australia Geologic faults or simply faults are planar rock fractures which show evidence of relative movement. ... In geology, a rift is a place where the Earths lithosphere is expanding. ...

Studies of the sequence of rocks show that the Vishnu Group underwent at least two periods of orogeny mountain-building. These orogenies created the 5 to 6 mile (8 to 10 km) high Mazatzal Mountains (Yavapai-Mazatzal orogeny).^[3] This was a very high mountain range, possibly as high as or higher than the modern Himalaya. Then, for over 500 million years, erosion stripped much of the exposed sediments and the mountains away. This reduced this very high range to small hills a few tens to hundreds of feet (tens of meters) high, leaving a major angular unconformity. The once deeply buried mountain roots were all that remained of the Mazatzal Mountains as the sea reinvaded. Orogeny is the process of mountain building, and as such is both a tectonic structural event, a geographical event and a chronological event, in that orogenic events happen within a time frame, affect certain regions of rocks and crust, and cause distinctive structural phenomena and related tectonic activity. ... Lyskamm, 4 527 m, Pennine Alps A mountain is a landform that extends above the surrounding terrain in a limited area. ... Perspective view of the Himalaya and Mount Everest as seen from space looking south-south-east from over the Tibetan Plateau. ...

During the late Cretaceous or early Tertiary time the Farallon tectonic plate subducted under the west coast of the North American plate causing a compressional force across the region that resulted in an uplift and the formation of the Colorado Plateau. The Cretaceous Period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i. ... For other uses, see Tertiary (disambiguation). ... The Farallon Plate is an ancient tectonic plate which began subducting as Pangaea broke apart during the Jurassic period. ... The Juan de Fuca plate sinks below the North America plate at the Cascadia subduction zone. ...  The North American plate, shown in brown The North American Plate is a tectonic plate covering most of North America, extending eastward to the Mid-Atlantic Ridge and westward to the Cherskiy Range in East Siberia. ... The Colorado Plateau, also called the Colorado Plateaus Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. ...

Grand Canyon Supergroup

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 (this rifting ultimately failed to split the continent). Eventually, a region of Laurentia from at least present-day Lake Superior to Glacier National Park in Montana to the Grand Canyon and the Uinta Mountains was invaded by a shallow seaway.^[4] The resulting Grand Canyon Supergroup of sedimentary units is composed of nine varied formations that were laid down from 1250 million to 825 million years ago in this sea. The total thickness of the sediment and lava deposited was well over 2 miles (3 km). Rock outcroppings of the Grand Canyon Supergroup appear in parts of the Inner Gorge and in some of the deeper tributary canyons. The tectonic plates of the world were mapped in the second half of the 20th century. ... The continental crust is the layer of granitic, sedimentary and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. ... USGS image In geology, a rift is a place where the Earths lithosphere is expanding. ... Lake Superior (known as Gichigami in an Ojibwe language), bounded by Ontario and Minnesota to the north and Wisconsin and Michigan in the south, is the largest of North Americas Great Lakes. ... There is also a non-adjoining national park in Canada by the same name. ... Official language(s) English Capital Helena Largest city Billings Area  Ranked 4th  - Total 147,165 sq mi (381,156 km²)  - Width 255 miles (410 km)  - Length 630 miles (1,015 km)  - % water 1  - Latitude 44°26N to 49°N  - Longitude 104°2W to 116°2W Population  Ranked... This view of Kings Peak and the Henrys Fork Basin shows the cliff bands and basins typical throughout the Uintas. ... Look up lava, Aa, pahoehoe in Wiktionary, the free dictionary. ...

The oldest section of the supergroup is the Unkar Group (a group is a set of two or more formations that are related in notable ways). It was laid down in an offshore environment Interstate road cut through limestone and shale strata in eastern Tennessee In geology and related fields, a stratum (plural: strata) is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers. ...

• Bass Limestone (averages 1250 million years old) – Wave action eroded the land, creating a gravel that later lithified into a basal conglomerate. This formation is known as the Hotauta Member of the Bass Limestone. The Bass Limestone formation was deposited in a shallow sea near the coast as a mix of limestone, sandstone, and shale. It is 120 to 340 feet (40 to 100 m) thick and grayish in color. This is the oldest layer exposed in the Grand Canyon that contains fossils—stromatolites.
• Hakatai Shale (averages 1200 million years old) – The Hakatai Shale is made of thin beds of non-marine-derived mudstones, sandstones, and shale. 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 – This formation was a resistant marine sandstone that later formed islands in Cambrian time. Those islands withstood wave action long enough to become re-buried by other sediments in the Cambrian Period. It was later metamorphosed into quartzite.
• Dox Sandstone (averages 1190 million years old) – A shallow formation made of ocean-derived sandstone with some interbedded shale beds and mudstone. 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.
• Cardenas Lava (1250 to 1100 million years old) – This is the youngest formation of the Unkar Group and is made of layers of dark brown basaltic rocks that flowed as lava up to 1000 feet (300 m) thick.

The Nankoweap Formation averages 1050 million years old and is not part of a group. 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 Lava. The Nankoweap is only exposed in the eastern part of the canyon. A gap in the geologic record, an unconformity, follows the Nankoweap. Limey shale overlaid by limestone. ... Gravel being unloaded from a barge Gravel is rock that is of a certain grain size range. ... A conglomerate with iron oxide cementing material A conglomerate (IPA: ) is a rock consisting of individual stones that have become cemented together. ... Limey shale overlaid by limestone. ... Red sandstone interior of Lower Antelope Canyon, Arizona, worn smooth due to erosion by flash flooding over millions of years Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. ... Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Pre-Cambrian stromatolites in the Siyeh Formation, Glacier National Park. ... Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Mudstone is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Quartzite Quartzite is a hard, metamorphic rock which was originally sandstone. ... The Cambrian is a major division of the geologic timescale that begins about 542 ± 1. ... Quartzite Quartzite is a hard, metamorphic rock which was originally sandstone. ... Red sandstone interior of Lower Antelope Canyon, Arizona, worn smooth due to erosion by flash flooding over millions of years Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. ... Oceans (from Okeanos in Greek) are saline waters that cover almost three quarters (71%) of the surface of the Earth. ... Look up lava, Aa, pahoehoe in Wiktionary, the free dictionary. ... Basalt Columnar basalt at Sheepeater Cliff in Yellowstone Basalt (IPA: ) is a common gray to black volcanic rock. ... Look up lava, Aa, pahoehoe in Wiktionary, the free dictionary. ...

All formations in the Chuar Group (about 1000 to 825 million years old) were deposited in coastal and shallow sea environments.^[5]

• Galeros Formation – A mainly greenish formation composed of interbedded sandstone, limestone, and shale with some shale ranging in color from red to purple. Fossilized stromatolites are found in the Galeros.
• Kwagunt Formation – The Kwagunt consists of black shale and red to purple mudstone with some limestone. Isolated pockets of reddish sandstone are also found around Carbon Butte. Stromatolites are found in this layer.
• Sixtymile Formation – Sixtymile 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.^[6] Some of the block units moved down and others moved up while fault movement created north-south-trending fault-block mountain ranges. Some 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 12,000 feet (3700 m) of the supergroup were removed entirely, exposing the Vishnu Group below. This created what geologist John Wesley Powell called the Great Unconformity, itself one of the best examples of an exposed nonconformity (an unconformity with bedded rock units above igneous or metamorphic rocks) in the world. In all some 250 million years of the area's geologic history was lost in the Great Unconformity.^[7] Good outcrops of the Grand Canyon Supergroup and the Great Unconformity can be seen in the upstream portion of the Inner Gorge. Old fault exposed by roadcut near Harrisburg, Pennsylvania. ... Fault-block mountains are produced when normal (near vertical) faults fracture a section of continental crust. ... First camp of the John Wesley Powell expedition, in the willows, Green River, Wyoming, 1871 John Wesley Powell (March 24, 1834 - September 23, 1902) was a U.S. soldier, geologist, and explorer of the American West. ... The Great Unconformity is a geologic feature where two adjacent layers of rock were not formed one after another in the earths development. ... There is a billion year gap in the geologic record where this 500 million year old dolomite unconformably overlays 1. ... Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... Metamorphic rock is the result of the transformation of a pre-existing rock type, the protolith, in a process called metamorphism, which means change in form, derived from the Greek words meta, change, and morphe, form. The protolith is subjected to extreme heat (>150 degrees Celsius) and pressure causing profound...

Tonto Group

When the ocean started to return to the area 550 million years ago in the Cambrian, it began to concurrently deposit the three formations of the Tonto Group as the shoreline moved eastward: The Cambrian is a major division of the geologic timescale that begins about 542 ± 1. ...

• Tapeats Sandstone (averages 545 million years old) – This formation is made of cliff-derived medium- to coarse-grained sand and conglomerate that was deposited on an ancient shore (see 3a in figure 1). Ripple marks are common in the upper members of this dark brown thin-bedded layer. Fossils and imprint trials of trilobites and brachiopods have also been found in the Tapeats. Today it is a cliff-former, 250 to 300 feet (75 to 90 m) thick.
• Bright Angel Shale (averages 530 million years old) – Bright Angel is made of mudstone shale interbeded 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. It is a slope-former, 325 to 400 feet (100 to 120 m) thick.
• Muav Limestone (averages 515 million years old) – The Muav is made of gray thin-bedded limestone that was deposited further offshore as calcium carbonate precipitates (see 3c in figure 1). It is fossil poor yet trilobites and brachiopods have been found in it. The western part of the canyon has a much thicker sequence of Muav than the eastern part.^[8] The Muav is a cliff-former, 250 to 375 feet (80 to 120 m) thick.

These three formations were laid down over a period of 30 million years from early to middle Cambrian time. Fossils of trilobites and burrowing worms are common in these formations. 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 with the Tapeats Sandstone and Muav Limestone forming cliffs, and the Bright Angel Shale forming slopes. Unlike the Paleozoic 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. Patterns in the sand Sand is a granular material made up of fine rock particles. ... A conglomerate with iron oxide cementing material A conglomerate (IPA: ) is a rock consisting of individual stones that have become cemented together. ... Download high resolution version (600x836, 67 KB)Photo of a display in the Grand Canyon visitors center. ... Subphyla and classes See Classification Brachiopods (from Latin bracchium, arm + New Latin -poda, foot) make up one of the major animal phyla, Brachiopoda. ... Dolomite crystals from Touissite, Morocco Dolomite is the name of both a carbonate rock and a mineral consisting of calcium magnesium carbonate (formula: CaMg(CO3)2) found in crystals. ... Earthworm A worm is an elongated soft-bodied invertebrate animal. ... Calcium carbonate is a chemical compound, with chemical formula CaCO3. ... Earthworm A worm is an elongated soft-bodied invertebrate animal. ... An aquifer is an underground layer of water-bearing permeable rock, or unconsolidated materials (gravel, sand, silt, or clay) from which groundwater can be usefully extracted using a water well. ... Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of geologic formations. ...

Temple Butte, Redwall, and Surprise Canyon

The next two periods of geologic history, the Ordovician and the Silurian, are missing from the Grand Canyon geologic 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 marks an unconformity of about 165 million years. The geologic timescale is used by geologists and other scientists to describe the timing and relationships between events that have occured during the history of the Earth. ... The Ordovician period is the second of the six (seven in North America) periods of the Paleozoic era. ... The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 443. ... Severe soil erosion in a wheat field near Washington State University, USA. For erosion as understood by materials science, see Erosion (materials science) For erosion as an English analogy, see Erosion (figurative) Erosion is the displacement of solids (soil, mud, rock and other particles) by the agents of wind, water... There is a billion year gap in the geologic record where this 500 million year old dolomite unconformably overlays 1. ...

Geologists do know that deep channels were carved on the top of the Muav Limestone during this time. Streams were the likely cause but marine scour may be to blame. Either way, these depressions were filled with freshwater limestone about 350 million years ago in the Middle Devonian in a formation that geologists call the Temple Butte Limestone (see 4a in figure 1). Marble Canyon in the eastern part of the park displays these filled purplish-colored channels well. The Temple Butte Limestone 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. An unconformity marks the top of this formation. The Temple Butte is 250 to 375 feet (80 to 120 m) thick. A running stream. ... Limey shale overlaid by limestone. ... Disambiguation: Devonian is sometimes used to refer to the Southwestern Brythonic language, and the people of the county of Devon are sometimes referred to as Devonians The Devonian is a geologic period of the Paleozoic era. ... Download high resolution version (600x836, 67 KB)Photo of a display in the Grand Canyon visitors center. ... Marble Canyon is the section of the Colorado River canyon from Glen Canyon Dam to the confluence with the Little Colorado River, which marks the beginning of the Grand Canyon. ... Dolomite crystals from Touissite, Morocco Dolomite is the name of both a carbonate rock and a mineral consisting of calcium magnesium carbonate (formula: CaMg(CO3)2) found in crystals. ... The backbone is a synonym for the spine of a vertebrate organism. ...

The next formation in the Grand Canyon geologic column is the cliff-forming Redwall Limestone, which is 450 to 525 feet (140 to 160 m) thick (see 4b in figure 1). The Redwall is composed of thick-bedded, dark brown to bluish gray limestone and dolomite with white chert nodules mixed in and was laid down in a retreating shallow tropical sea near the equator in early to middle Mississippian time (about 335 million years ago). 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. Caves and natural arches are also found. After this formation was deposited the Grand Canyon region was slowly uplifted, and part of the upper Redwall was eroded away in late Mississippian. The exposed surface of the Redwall gets its characteristic color from rainwater dripping from the redbeds of the Supai and Hermit shale that lie above. Chert Chert (IPA: ) is a fine-grained silica-rich cryptocrystalline sedimentary rock that may contain small fossils. ... The tropics are the geographic region of the Earth centered on the equator and limited in latitude by the two tropics: the Tropic of Cancer in the north and the Tropic of Capricorn in the southern hemisphere. ... World map showing the equator in red The Equator is an imaginary circle drawn around a planet (or other astronomical object) at a distance halfway between the poles. ... This article is about the geologic period; for the North American culture, see Mississippian culture. ... Orders Articulata Cladida(extinct) Flexibilia(extinct) Camerata(extinct) Disparida(extinct) Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the echinoderms (phylum Echinodermata). ... Subphyla and classes See Classification Brachiopods (from Latin bracchium, arm + New Latin -poda, foot) make up one of the major animal phyla, Brachiopoda. ... Fossilized Bryozoa, Ordovician limestone, Batavia, Ohio Bryozoans (moss animals) are tiny colonial animals that generally build stony skeletons of calcium carbonate, superficially similar to coral. ... Also called tetracoralla, the Rugosa are an extinct group of corals that were abundant in Middle Ordovician to Late Permian seas. ... Orders Palcephalopoda †Plectronocerida †Ellesmerocerida †Actinocerida †Pseudorthocerida †Endocerida †Tarphycerida †Oncocerida †Discosorida Nautilida Neocephalopoda (in part) †Orthocerida †Ascocerida †Bactritida Nautiloids are a group of marine mollusks in the subclass Nautiloidea, which all possess an external shell, the best-known example being the modern nautiluses. ... Classes Calcarea Hexactinellida Demospongiae The sponges or poriferans (from the Greek poros pore and ferro to bear) are animals of the phylum Porifera. ... Lechuguilla Cave, New Mexico This article is about natural caves; for artificial caves used as dwellings, such as those in north China, see yaodong. ... Rainbow Bridge was formed by a meandering watercourse A natural arch or natural bridge is a formation (or landform) where a rock arch forms, with a natural passageway through underneath. ... For the singer, see Rain (singer). ...

The Surprise Canyon Formation is a sedimentary layer of purplish-red shale that was laid down in discontinuous beds above the Redwall (see 4c in figure 1). It was created by evolving tidal estuaries in very late Mississippian and possibly in very earliest Pennsylvanian time. This formation, which only exists in isolated lenses up to 40 feet (12 m) thick, can only be reached by helicopter. It was unknown to science until the 1980s.^[9] 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. Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Estuaries and coastal waters are among the most productive ecosystems on Earth, providing ecological, economic, cultural, and aesthetic benefits. ... The Pennsylvanian is an epoch of the Carboniferous period lasting from roughly 325 Ma to 299 Ma (million years ago). ... Robinson Helicopter Company (USA) R44, a four seat development of the R22 A helicopter is an aircraft which is lifted and propelled by one or more horizontal rotors, each having two or more rotor blades. ...

Supai Group

The Supai Group was deposited in Pennsylvanian and early Permian time in swampy and riparian environments from clastic sediment mostly derived from the Ancestral Rocky Mountains (the average age of this group is 285 million years). The Supai in the western park of the canyon contains limestone, indicative of a warm, shallow sea, while the eastern part was likely a muddy river delta. This formation consists of red siltstones and shale capped by tan-colored sandstone beds that together reach a thickness of 600 to 700 feet (180 to 210 m). Shale in the early Permian formations in this group were oxidized to a bright red color. Fossils include amphibian footprints, reptiles, and plentiful plant material in the eastern part and increasing numbers of marine fossils in the western part. The formations of the Supai Group are (from oldest to youngest; an unconformity is present at the top of each): The Permian is a geologic period that extends from about 299. ... A freshwater swamp This article is about the wetland type (a landform). ... A riparian zone schematic from the Everglades. ... Moraine Lake, and the Valley of the Ten Peaks, Banff National Park, Alberta, Canada The Rocky Mountains, often called the Rockies, are a broad mountain range in western North America. ... Siltstone Siltstone is a geological term for a sedimentary rock whose composition is intermediate in grain size between the coarser sandstone and the finer mudstone. ... Red sandstone interior of Lower Antelope Canyon, Arizona, worn smooth due to erosion by flash flooding over millions of years Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. ... The most fundamental reactions in chemistry are the redox processes. ... For other uses, see Amphibian (disambiguation). ... Subclasses Anapsida Diapsida Reptiles are tetrapods and amniotes, animals whose embryos are surrounded by an amniotic membrane. ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta - liverworts Anthocerotophyta - hornworts Bryophyta - mosses Vascular plants (tracheophytes) †Rhyniophyta - rhyniophytes †Zosterophyllophyta - zosterophylls Lycopodiophyta - clubmosses †Trimerophytophyta - trimerophytes Pteridophyta - ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering plants...

• Watahomigi (see 5a in figure 1): Slope-forming gray limestone with some red chert bands, sandstone, and purple siltstone that is 90 to 175 feet (30 to 50 m) thick.
• Manakacha (see 5b in figure 1): Cliff- and slope-forming pale red sandstone and red shale that is 200 to 275 feet (60 to 85 m) thick.
• Wescogame (see 5c in figure 1): Ledge- and slope-forming pale red sandstone and siltstone that is 100 to 225 feet (30 to 70 m) thick.
• Esplanade (see 5d in figure 1): Ledge- and cliff-forming pale red sandstone and siltstone that is 225 to 300 feet (70 to 90 m) thick.^[10]

An unconformity marks the top of the Supai Group. Download high resolution version (600x836, 67 KB)Photo of a display in the Grand Canyon visitors center. ...

Hermit, Coconino, Toroweap, and Kaibab

Like the Supai Group below it, the Hermit Shale was deposited in a swampy environment (see 6a in figure 1). The alternating thin-bedded iron oxide, mud and silt were deposited via freshwater streams in a semiarid environment an average of 265 million years ago. Fossils of winged insects, cone-bearing plants, and ferns are found in this formation as well as tracks of amphibians and reptiles. It is a soft, deep red shale and mudstone slope-former in the canyon that is 160 to 175 feet (49 to 53 m) 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. An unconformity marks the top of this formation. Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Download high resolution version (600x836, 67 KB)Photo of a display in the Grand Canyon visitors center. ... Iron oxide pigment There are a number of iron oxides: Iron oxides Iron(II) oxide or ferrous oxide (FeO) The black-coloured powder in particular can cause explosions as it readily ignites. ... In computer gaming, a MUD (Multi-User Dungeon or Domain or Dimension) is a multi-player computer game that combines elements of role-playing games, hack and slash style computer games and social chat rooms. ... Silt is soil or rock derived granular material of a specific grain size. ... Three small ammonite fossils, each approximately 1. ... Orders See taxonomy Insects are invertebrates that are taxonomically referred to as the class Insecta. ... Classes Psilotopsida Equisetopsida Marattiopsida Polypodiopsida A fern is any one of a group of about 20,000 species of plants classified in the phylum or division Pteridophyta, also known as Filicophyta. ... Mudstone is a fine-grained sedimentary rock whose original constituents were clays or muds. ...

The Coconino Sandstone formed as the area dried out and sand dunes made of pure quartz sand invaded a growing desert some 260 million years ago (see 6b in figure 1). Today, it is a 375 to 650 ft (115 to 200 m) thick golden white to cream-colored cliff-former near the canyon's rim. Eolian (wind-created) cross bedding patterns of the frosted, well-sorted and rounded sand can be seen in its fossilized sand dunes. Also fossilized are arthropod and early reptile tracks along with some burrows. An unconformity marks the top of this formation. Coconino Sandstone is a geologic formation that spreads across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah. ... This article is about the sand formations, for other meanings see Dune (disambiguation) Mesquite Flat Dunes in Death Valley National Park In physical geography, a dune is a hill of sand built by eolian (wind-related) processes. ... Quartz is one of the most common minerals in the Earths continental crust. ... Erg Chebbi, Morocco In geography, a desert is a landscape form or region that receives very little precipitation. ... Cross bedding is a geological term referring to the way a sedimentary deposit is affected by water currents, during its formation. ... Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ...

Next in the geologic column is the Toroweap Formation, 200 to 250 feet (60 to 75 m) thick (see 6c in figure 1). It consists of red and yellow sandstone and shaly gray limestone interbedded with gypsum that were deposited in a warm, shallow sea as its shoreline transgressed (invaded) and regressed (retreated) over the land (average age of the rock is about 250 million years). In modern times it is a ledge- and cliff-former that contains fossils of brachiopods, corals, and mollusks along with other animals and various terrestrial plants. The Toroweap is divided into the following three members: Red sandstone interior of Lower Antelope Canyon, Arizona, worn smooth due to erosion by flash flooding over millions of years Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. ... Gypsum is a very soft mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. // Heating gypsum to between 100°C and 150°C (302°F) partially dehydrates the mineral by driving off exactly 75% of the water contained in its chemical structure. ... Subclasses Alcyonaria Zoantharia See text for orders. ... Classes Caudofoveata Aplacophora Polyplacophora Monoplacophora Bivalvia Scaphopoda Gastropoda Cephalopoda † Rostroconchia The mollusks or molluscs are the large and diverse phylum Mollusca, which includes a variety of familiar creatures well-known for their decorative shells or as seafood. ...

• Seligman: Slope-forming yellowish to reddish sandstone and siltstone.
• Brady Canyon: Cliff-forming gray limestone with some chert.
• Wood Ranch: Slope-forming pale red and gray siltstone and dolomitic sandstone.

An unconformity marks the top of this formation. Chert Chert (IPA: ) is a fine-grained silica-rich cryptocrystalline sedimentary rock that may contain small fossils. ...

One of the highest, and therefore youngest, formations seen in the Grand Canyon area is the massive Kaibab Limestone, 250 to 350 feet (80 to 110 m) thick (see 6d in figure 1). A prominent ledgy cliff-former, the Kaibab Limestone was laid down in middle Permian time an average of about 225 million years ago in the deeper parts of the same advancing warm, shallow sea that deposited the underlying Toroweap Formation. The Kaibab is typically made of sandy limestone sitting on top of a layer of sandstone, but in some places sandstone and shale are near or at the top.^[11] This is the cream to grayish-white rock that park visitors stand on while enjoying the spectacular vistas of the canyon from both rims (some call it "Grand Canyon's bathtub ring" due to its appearance). 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 abundant fossils of marine invertebrates such as brachiopods, corals, mollusks, sea lilies, and worms. An unconformity marks the top of this formation. The Kaibab is a geologic formation that is spread across the U.S. states of northern Arizona, southern Utah, east central Nevada and southeast California. ... The Kaibab Plateau is located in northern Arizona in the United States. ... The Coconino Plateau is found north and northwest of Flagstaff, Arizona, in the United States. ... Orders Carcharhiniformes Heterodontiformes Hexanchiformes Lamniformes Orectolobiformes Pristiophoriformes Squaliformes Squatiniformes Sharks (superorder Selachimorpha) are fish with a full cartilaginous skeleton[1] and a streamlined body. ... Invertebrate is a term coined by Jean-Baptiste Lamarck to describe any animal without a spinal column. ... Classes Caudofoveata Aplacophora Polyplacophora Monoplacophora Bivalvia Scaphopoda Gastropoda Cephalopoda † Rostroconchia The mollusks or molluscs are the large and diverse phylum Mollusca, which includes a variety of familiar creatures well-known for their decorative shells or as seafood. ... Orders Articulata Cladida (extinct) Flexibilia (extinct) Camerada (extinct) Disparida (extinct) Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the echinoderms (phylum Echinodermata). ...

Mesozoic deposition

Reddish Moenkopi outcrop below volcanic rubble on Red Butte

Uplift marked the start of the Mesozoic and streams started to incise the newly dry land. Broad, low valleys deposited sediment eroded from nearby uplands in Triassic time creating the once 1000 foot (300 m) thick Moenkopi Formation. The formation is made from sandstone and shale with gypsum layers in between. This easily eroded formation may have been deposited above the rim of the Grand Canyon. 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.^[12] Image File history File linksMetadata Download high resolution version (2272x1704, 614 KB) West face of Red Butte, Arizona. ... Image File history File linksMetadata Download high resolution version (2272x1704, 614 KB) West face of Red Butte, Arizona. ... Red Butte is located in the Kaibab National Forest in Coconino County, Arizona. ... The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. ... Severe soil erosion in a wheat field near Washington State University, USA. For erosion as understood by materials science, see Erosion (materials science) For erosion as an English analogy, see Erosion (figurative) Erosion is the displacement of solids (soil, mud, rock and other particles) by the agents of wind, water... The Triassic is a geologic period that extends from about 251 to 200 Ma (million years ago). ... The Moenkopi is a formation that is spread across the U.S. states of New Mexico, northern Arizona, Nevada, southeastern California, eastern Utah and western Colorado. ... Gypsum is a very soft mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. // Heating gypsum to between 100°C and 150°C (302°F) partially dehydrates the mineral by driving off exactly 75% of the water contained in its chemical structure. ... Colorado River in the Grand Canyon from Desert View The Colorado River is a river in the southwestern United States and northwestern Mexico, approximately 1,450 mi (2,333 km) long, draining a part of the arid regions on the western slope of the Rocky Mountains. ... Marble Canyon is the section of the Colorado River canyon from Glen Canyon Dam to the confluence with the Little Colorado River, which marks the beginning of the Grand Canyon. ... Cedar Mountain, Nevada Earthquake of 1932 December 21, 1932 Magnitude 7. ... Several mesas near Los Alamos, New Mexico. ... Red Butte is located in the Kaibab National Forest in Coconino County, Arizona. ... Grand Canyon Village is a census-designated place located right on the south rim of the Grand Canyon, in Coconino County, Arizona. ...

Formations totaling over 5000 feet (1500 m) 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 (see below). For details on these layers see geology of the Zion and Kolob canyons area, and geology of the Bryce Canyon area. All these rock units together form a super sequence of rock known as the Grand Staircase. The Cenozoic Era (IPA pronunciation: ); sometimes Caenozoic Era in the United Kingdom) meaning new life (Greek kainos = new + zoe = life) is the most recent of the three classic geological eras. ... Kolob Canyons from the end of Kolob Canyons Road. ... The exposed geology of the Bryce Canyon area 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 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. ...

Creation of the Grand Canyon

Uplift and nearby extension

Uplift of the Colorado Plateaus forced rivers to cut down faster.

The Laramide orogeny affected all of western North America by helping to build the Cordilleran Mountain Range (of which the Rocky Mountains are a major part). This major mountain-building event started near the end of the Mesozoic (around 75 million years ago) and lasted well into the early Cenozoic. A second period of uplift started 17 million years ago, creating the Colorado Plateaus (the Kaibab, Kanab, and Shivwits plateaus bound the northern part of the canyon and the Cococino bounds the southern part). However, for reasons poorly understood, the beds of the Colorado Plateaus remained mostly horizontal through both events even as they were uplifted an estimated 9000 feet (2700 m). One hypothesis suggests that the entire plateau shifted in a clockwise rotation during the uplift and this helped to maintain its stability. Before the uplift the plateau region was about 1000 feet (300 m) above sea level and bounded by high mountains to the south and west. NPS image [1] Edited with the GIMP This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... The Laramide orogeny was a period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. ... World map showing North America A satellite composite image of North America. ... The American cordillera consists of an essentially continuous sequence of mountain ranges that form the western backbone of both North America and South America. ... Moraine Lake, and the Valley of the Ten Peaks, Banff National Park, Alberta, Canada The Rocky Mountains, often called the Rockies, are a broad mountain range in western North America. ... The Colorado Plateau, also called the Colorado Plateaus Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. ... The Kaibab Plateau is located in northern Arizona in the United States. ... For considerations of sea level change, in particular rise associated with possible global warming, see sea level rise. ... Lyskamm, 4 527 m, Pennine Alps A mountain is a landform that extends above the surrounding terrain in a limited area. ...

In middle Tertiary time (about 20 million years ago) tensional forces (crustal stretching) created and expanded faults in the area and caused some moderate volcanic activity. To the west, these forces created the Basin and Range province by forming long north-south-trending faults along which basins (grabens) dropped down and mountain ranges (horsts) were uplifted. The extreme western part of the park is intersected by one of these faults, the Grand Wash. For other uses, see Tertiary (disambiguation). ... Fault in metamorphosed strata near Adelaide, Australia Geologic faults or simply faults are planar rock fractures which show evidence of relative movement. ... This article is about volcanoes in geology. ... Basin and Range index map - USGS The Basin and Range Province is a particular type of topography that covers much of the southwestern United States and northwestern Mexico that is typified by elongate north-south trending arid valleys bounded by mountain ranges which also bound adjacent valleys. ... USGS image A graben is a depressed block of land bordered by parallel faults. ... USGS image In physical geography and geology, a horst is the raised fault block bounded by normal faults. ...

The Colorado River is born and cuts down

The Colorado River had cut down to nearly the current depth of the Grand Canyon by 1.2 million years ago.

Continued uplift of the Colorado Plateaus created monoclines and also increased the elevation of its plateaus. This steepened the gradient of streams flowing in the Colorado Plateaus province. The ancestral Colorado River was a landlocked river until 5.3 million years ago (see below). Before that it had a series of temporary base levels (lowest points) in large lakes in the Colorado Plateaus in the early Tertiary and possibly the Basin and Range by the middle Tertiary.^[13] Image taken in April 2004 by Daniel Mayer. ... Image taken in April 2004 by Daniel Mayer. ... A fold in Slichowice nature reserve in Kielce (Variscan orogeny) The term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of plastic (i. ... Stream gradient is the ratio of drop in a stream per unit distance, usually expressed as feet per mile or meters per kilometer. ... Colorado River in the Grand Canyon from Desert View The Colorado River is a river in the southwestern United States and northwestern Mexico, approximately 1,450 mi (2,333 km) long, draining a part of the arid regions on the western slope of the Rocky Mountains. ... For other uses, see Tertiary (disambiguation). ...

The opening of an arm of the Gulf of California 5.3 million years ago changed the direction of nearby streams toward the sagging and rifting region. The upstream uplift and downstream sagging caused streams flowing into the gulf to run and downcut much faster. Soon (geologically speaking) headwater capture consolidated these streams into one major river and associated tributary channels—the modern Colorado drainage system. The most important consolidation occurred when a separate preexisting river that was carving a channel into the San Andreas Fault and out into the gulf likely captured the landlocked Colorado.^[14] Excavation of the eastern part of the Grand Canyon began previous to this but was greatly accelerated and expanded west afterward. The Gulf of California (also known as the Sea of Cortez or Sea of Cortés; locally known in the Spanish language as Mar de Cortés or, much less frequently, Golfo de California) is a body of water that separates the Baja California Peninsula from the Mexican mainland. ... Erosional downcutting by the San Juan River in Utah. ... Stream capture is a geological or hydrological phenomenon which occurs when a stream from a neighboring drainage system erodes through the divide between two streams and captures another stream which then is diverted from its former bed and now flows down the bed of the capturing stream. ... View of the San Andreas Fault on the Carrizo Plain in central California, 35°07N, 119°39W The San Andreas Fault is a geological fault that runs a length of roughly 800 miles (1300 kilometres) through western and southern California in the United States. ...

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, steepened gradient, and lower base level, the Colorado cut faster than ever before and started to quickly excavate the Grand Canyon two million years before present, almost reaching the modern depth by 1.2 million years ago.^[15] Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ... The Pleistocene epoch (IPA: ) is part of the geologic timescale. ... A pluvial lake is a lake which experiences significant increase in depth and extent as a result of increased precipitation and reduced evaporation. ... Severe soil erosion in a wheat field near Washington State University, USA. For erosion as understood by materials science, see Erosion (materials science) For erosion as an English analogy, see Erosion (figurative) Erosion is the displacement of solids (soil, mud, rock and other particles) by the agents of wind, water... Spring is one of the four seasons of temperate zones, the transition from winter into summer. ... Lower Antelope Canyon was carved out of sandstone by flash floods A Flash Flood is a rapid flooding of geomorphic low-lying areas (washes), rivers and streams, caused by the intense rainfall associated with a thunderstorm, or multiple training thunderstorms. ... For other uses, see Summer (disambiguation). ...

Volcanic activity dams the new canyon

Vulcan's Throne volcano above Lava Falls. Lava flows like this heavily eroded remnant once dammed the Colorado River.

In later Pleistocene time, around one to two million years ago, basaltic lava covered part of the area and in places cascaded down side canyons, even damming the western part of the canyon between miles 178 and 188 (286 and 302 km) in the Mount Trumbull area. The river was dammed in this way at least 13 times from 1.8 million to 400,000 years ago.^[16] Download high resolution version (1400x1117, 1024 KB)USGS image by Balsley, J.R., taken in 1950. ... Download high resolution version (1400x1117, 1024 KB)USGS image by Balsley, J.R., taken in 1950. ... Basalt Columnar basalt at Sheepeater Cliff in Yellowstone Basalt (IPA: ) is a common gray to black volcanic rock. ... Look up lava, Aa, pahoehoe in Wiktionary, the free dictionary. ... Scrivener Dam, in Canberra, Australia, was engineered to withstand a once-in-5000-years flood A dam is a barrier across flowing water that obstructs, directs or retards the flow, often creating a reservoir, lake or impoundment. ...

Three of these lava dams were over 1000 feet (300 m) high, forming lakes similar to reservoirs such as Lake Mead or Lake Powell. Some of the lakes were over 100 miles (160 km) long and 200 to 2000 feet (60 to 600 m) deep for many years, before finally over-topping the dam and eroding much of it away in massive cascading waterfalls (it took about 20,000 years from start of each dam's formation to its destruction). Cinder cones and the remnants of lava flows are visible in the Toroweap area, and the remains of some of the dams exist today as rapids such as Lava Falls. A man-made lake in Keukenhof, Netherlands A lake is a body of water or other liquid of considerable size surrounded by land. ... A man-made lake in Keukenhof, Netherlands A lake is a body of water or other liquid of considerable size surrounded by land. ... Panoramic view of Lake Mead. ... Lake Powell is a man-made reservoir on the Colorado River, straddling the border between Utah and Arizona. ... Hopetoun Falls near Otway National Park, Victoria, Australia A waterfall is usually a geological formation resulting from water, often in the form of a stream, flowing over an erosion-resistant rock formation that forms a sudden break in elevation. ... Cinder Cone is a cinder cone volcano in Lassen Volcanic National Park. ... A rapid is a section of a river where it loses elevation over a relatively short distance (that is, the stream gradient is locally steepened), causing an increase in water flow and (usually) turbulence. ...

Recent geology, human impact, and the future

Glen Canyon Dam has greatly reduced the amount of sediment transported by the Colorado River through the Grand Canyon.

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 (although much of the rim then, as now, received enough precipitation to support large forests). With less water to cut, the erosive ability of the Colorado was greatly reduced (the rocks of the Inner Gorge are also relatively resistant to erosion). Mass wasting processes thus began to become relatively more important than they were before, creating steeper cliffs and further widening the Grand Canyon and its tributary canyon system. USGS image from http://geology. ... USGS image from http://geology. ... The Holocene epoch is a geological period that extends from the present day back to about 10,000 radiocarbon years, approximately 11,430 ± 130 calendar years BP (between 9560 and 9300 BC). ... Eucalyptus Forest at Swifts Creek in East Gippsland, Victoria, Australia. ... Mass wasting, also known as mass movement or slope movement, is the geomorphic process by which soil, regolith, and rock move downslope under the force of gravity. ...

In modern times, the building of the Glen Canyon Dam and other dams further upstream have regulated the flow of the Colorado River and have substantially reduced the amount of water and sediment it carries. This has diminished the river's ability to scour rocks, and the demand for water is so great that in most years the Colorado does not reach its delta in the Gulf of California. Glen Canyon Dam on 19 June 2005. ... River Gambia flowing through Niokolokoba National Park A river is a large natural waterway. ... Nile River delta, as seen from Earth orbit. ... The Gulf of California (also known as the Sea of Cortez or Sea of Cortés; locally known in the Spanish language as Mar de Cortés or, much less frequently, Golfo de California) is a body of water that separates the Baja California Peninsula from the Mexican mainland. ...

The dam has also changed the character of the river water. Once both muddy and warm, with only bottom feeding fish, the river is now clear and cold and now supports planted trout. This in turn has changed the migration patterns of the bald eagle, which previously would transit the canyon to favorable fishing sites downstream, but now use the river as their seasonal feeding site. Rainbow trout, Oncorhynchus mykiss Biwa trout, Oncorhynchus masou subsp Trout is the common name given to a number of species of freshwater fish belonging to the salmon family, Salmonidae. ... Binomial name Haliaeetus leucocephalus (Linnaeus, 1766) Subspecies (Linnaeus, 1766) Southern Bald Eagle Audubon, 1827) Northern Bald Eagle or Washingtons Eagle Synonyms Falco leucocephalus Linnaeus, 1766 The Bald Eagle (Haliaeetus leucocephalus), also known in North America as the American Eagle, is a bird of prey found in North America, most...

About 45 earthquakes occurred in or near the Grand Canyon in the 1990s. Of these, five registered between 5.0 and 6.0 on the Richter Scale. Dozens of faults cross the canyon, with at least several active in the last 100 years. An earthquake is a phenomenon that results from the sudden release of stored energy in the Earths crust that creates seismic waves. ... The Richter magnitude test scale (or more correctly local magnitude ML scale) assigns a single number to quantify the size of an earthquake. ...

The stream gradient of the Colorado River is still steep enough to suggest that the river could cut another 1200 to 2000 feet (400 to 600 m) assuming no additional uplift in the geologic future. This does not account for human impact, which would tend to slow the rate of erosion.

References

Works cited

Grand Canyon from a trail below Grandview Point

In order of greatest use. Download high resolution version (1000x1204, 205 KB)Image of the Grand Canyon from Grandview Point taken on April 9, 2004 by Daniel Mayer. ... Download high resolution version (1000x1204, 205 KB)Image of the Grand Canyon from Grandview Point taken on April 9, 2004 by Daniel Mayer. ...

• Geology of National Parks: Fifth Edition, Ann G. Harris, Esther Tuttle, Sherwood D. Tuttle (Iowa, Kendall/Hunt Publishing; 1997) ISBN 0-7872-5353-7
• Geology of U.S. Parklands: Fifth Edition, Eugene P. Kiver, David V. Harris (New York; John Wiley & Sons; 1999; pages 397-409) ISBN 0-471-33218-6
• Kaibab.org, Grand Canyon Rock Layers, The Geology of the Grand Canyon (viewed 19-20 March 2005)
• Secrets in The Grand Canyon, Zion and Bryce Canyon National Parks: Third Edition, Lorraine Salem Tufts (North Palm Beach, Florida; National Photographic Collections; 1998) ISBN 0-9620255-3-4
• Grand Canyon: The Continuing Story, Connie Rudd (KC Publishing, Inc.; 1990) ISBN 0-88714-046-7
• The Colorado River Super Guide Map of the Grand Canyon, Bronze Black (Flagstaff, Arizona; Dragon Creek Publishing; 2003)
• Geology of Grand Canyon National Park, North Rim by Annabelle Foos
• "Grand Canyon: Solving Earth's Grandest Puzzle", James Lawrence Powell (Pi Press 2005) ISBN 0-13-147989-X

Notes

1. ^ Geology of U.S. Parklands, page 398
2. ^ Pages of Stone: Geology of the Grand Canyon & Plateau Country National Parks & Monuments, page 100
3. ^ Secrets in the Grand Canyon, Zion and Bryce Canyon National Parks, page 10
4. ^ Geology of U.S. Parklands, page 398
5. ^ Kaibab.org, "The Geology of the Grand Canyon: When did this all happen?" and "Grand Canyon Rock Layers"
6. ^ Geology of National Parks, page 11 and Geology of U.S. Parklands, page 399
7. ^ Kaibab.org, "The Geology of the Grand Canyon: When did this all happen?"
8. ^ Kaibab.org, "Grand Canyon Rock Layers"
9. ^ Geology of National Parks, page 23, 3, Retrieved 4 January 2007
10. ^ http://www2.nature.nps.gov/geology/education/foos/grand.pdf
11. ^ Kaibab.org, "Grand Canyon Rock Layers"
12. ^ Geology of U.S. Parklands, page 405
13. ^ Geology of U.S. Parklands, page 405
14. ^ Kaibab.org, "The Geology of the Grand Canyon: Why does it look like it does?"
15. ^ Geology of U.S. Parklands, page 407
16. ^ Geology of U.S. Parklands, page 407

External links

• USGS: Geologic studies to support restoration of the Grand Canyon environment
• pbs.org: Geologic timelime for the Grand Canyon
• J. David Rogers' Grand Canyon Research Volcanism
• Interactive Hypermedia on GC geology & Colin Fletcher's trek through the Canyon likened to a Bach fugue [shockwave required]