The Formation Of Devils Tower
Of the Great Plains in Wyoming, Devils Tower is an “upstanding” feature. It is located on the northwestern part of the Black Hills-Bear Lodge uplift, which is a mountainous region. During the Laramide Orogeny, about 60 million years ago, this region formed. The process of the formation of mountains is called an orogeny. Rocky Mountain ranges, such as the Bighorn Mountains and Uinta Mountains were formed by the Laramide Orogeny.
Devil Tower stands 867 feet from base to summit, and above sea level its elevation is 5,112 feet and around 1,267 feet above the north-flowing Belle Fourche River. Sedimentary, igneous, and erosional processes led to the formation of Devils Tower National Monument. First, sedimentary rocks in layers, which are nearly two miles thick, were deposited. About 500 million years ago, most of the layers were deposited in shallow seas. Igneous activity then created the tower until erosional processes exposed it.
The Black Hills region, which is an elliptical dome, was formed …show more content…
through tectonic processes; the rocks were uplifted, fractured, and faulted. The oldest rocks, which are located at a high and central part of the dome, have been eroded the most. Precambrian granites at Mount Rushmore National Park contain older rocks, whereas Triassic Jurassic sedimentary rocks contain younger rocks with less erosion. Younger rocks are more along the edges of the dome. Granites are igneous rocks, in which they have formed from magma that cools below Earth’s surface. Sedimentary rocks form from the consolidation of sediment.
Magma welled up into the older sedimentary rocks, about 50 million years ago. One of the magma bodies became Devils Tower. The magma cooled underground and never reached the surface, which remained buried under sedimentary rock that was more than a mile for many millions of years. The entire Rocky Mountain region was uplifted above sea level, about 5 million years ago, which made the rivers flow aggressively, down into soft sedimentary rocks. Eroded material were carried away and deposited into the Gulfs of Mexico and California. Soft sedimentary rocks, that covered the Tower, were removed by the Belle Fourche River. Igneous rock of the Devils Tower was exposed at the surface.
Layers of sedimentary rocks are formed by mud, sand, and other sediments at Earth’s surface, and are deposited in environments, such as oceans, rivers, and deserts. Solid rock is formed when layers of sand and mud become buried and the weight of additional, overlying material compress mud and sand. Sedimentary rocks are indicators of ancient landscapes, because they begin to form at Earth’s surface. Usually underwater and in layers, the oldest sedimentary rocks are on the bottom while the youngest rocks are on top. Sandstones form cliffs and ledges, because they are harder and more resistant than mudstones. Mudstones form soft and crumbly slopes.
Mudstones and sandstones are named based on their grain size; in the depositional environment, this is an indication of the energy of the currents. Sandstones have a high energy environment, because fast currents are strong enough to move large grains of sand and gravel. Stream channels, windy deserts, and ocean beaches may have currents from high energy environments. Deep Ocean, lakes, and swamps have deposits from mudstones. Mudstones are made up of fine, silt and clay size grains. A particle that is finer than sand and coarser than class is called silt. Fine-grained sediments or soft rock that contain clay-size or colloidal particles is clay.
Fossils, which are remains and traces of past life, are mostly made up of sedimentary rocks. Fossils provide information, such as where sediments have been deposited in an environment. A rock that contains corals and other marine fossils are remains of the ocean environment. Land environments may contain dinosaur fossils. Fossil pollen and other clues are documented to determine the type of environment the organism died at.
The Spearfish, Gypsum Springs, and Sundance formations are three different sedimentary rock layers that are exposed and can be seen along the Red Beds Trail at Devils Tower. Spearfish Formation, of sedimentary rocks, contains the oldest rocks. Spearfish Formation was named after Spearfish, South Dakota. The formation contains layers of bright, red-colored mudstone at low elevations. In the formation, white layers contain a mineral called gypsum, in which is composed of calcium sulfate with two molecules of water. Drywall is made up of gypsum. Gypsum forms when a white crust is left behind when saline water is evaporated in hot, dry conditions.
Approximately 240 million years ago, during the Triassic time, the Spearfish Formation was deposited. During this time, North America, South America and Africa were joined together near the equator; therefore, the Atlantic Ocean and Gulf of Mexico had not formed yet. Triassic age rocks contain the oldest dinosaur fossils.
Mudstones and very fine-grained sandstones make up the Spearfish Formation. On a flat, hot desert plain near the ocean, a fairy low-energy environment had deposited the Spearfish Formation. Iron forms a rusty, red color in sediments. In a hot, dry desert climate, iron was oxidized. Sediments would “rust”, as a result from them being moistened and then dried repeatedly.
Above the red rocks of the Spearfish Formation, contains Gypsum Springs Formation, which only appears as a thin white layer. The mineral gypsum is mostly made up of Gypsum Springs Formation. Gypsum is soft and easily erodible, and forms when saline water evaporates in hot, dry climates, such as the Gypsum Springs Formation. This formation was formed about 150 million years ago, during the Jurassic Period . North America, South America, and Africa began to separate, and form the Atlantic Ocean and Gulf of Mexico. Dinosaur tracks have been discovered in the Gypsum Springs Formation.
The Devils Tower is located in a coastal desert, whereas Death Valley lay in an inland desert environment. The process of gypsum forms is the same in both of these areas. Before the Rocky Mountains had formed, Devils Tower existed on a desert shoreline. During the Jurassic period, Devils Tower area would have been flat, hot, and not mountainous.
The youngest sedimentary rocks are contained within the Sundance Formation. Both a mudstone and a sandstone layer exist within this formation. The gray slope of Stockade Beaver mudstone is under the Yellow Hulett Sandstone that has formed a cliff. The sandstones at this formation at the Tower were deposited from waves that left ripple marks frozen into the sand on a Jurassic coastline.
Sundance Formation is Jurassic age. Africa and South America moved away from North America; the Atlantic Ocean and Gulf of Mexico formed. A shallow sea, called the Sundance Sea, was where deposits of the Sundance Formation formed. During this time period, the sea covered a lot of the Rocky Mountains; Devils Tower was submerged. Near the shoreline in shallow water, and close to a sandy beach was where the Hulett Sandstone was deposited. Farther offshore, in quieter water was where the Stockade Beaver underlying mudstone layer was deposited.
Dinosaur tracks are located throughout the Sundance Formation, when they walked across a shallow tidal flat that was covered with algal mats. Algal mats contain various species of algae. During photosynthesis, the mats produce gasses that cause the mats to rise to the surface. This layer at Devils Tower contains the most fossils, such as oyster shells and remains of fossil squid called belemnites.
Above the Sundance formation, more than 7,000 feet of younger sedimentary rocks were deposited over the next 100 million years. Younger rocks were removed by erosion, but have been preserved in the Powder River Basin. Material from erosion, during this episode, is equivalent to five times the height of the Sears Tower that is located in Chicago.
How fast magma cooled can be determined by the size of crystals in igneous rocks. Crystals have a long time to form and can grow largely when magma cooled deep underground. This can trap heat, because it can be insulated by overlying layers. Intrusive igneous rock is the result of this formation. Crystals that are large enough to see with the naked eye are called phaneritic. Crystals that do not have time to grow large form when magma cools quickly that has exploded or flowed onto Earth’s surface. This is called extrusive igneous rock. These crystals cannot be seen with the naked eye, and their texture is called aphanitic.
It may take tens of thousands or millions of years for a large mass of magma to solidify.
Large crystals, that contained molten lava and change environments by moving into an area with lower temperatures, would cool quickly. A porphyritic texture is where large and small crystals are embedded; therefore, porphyry contains this texture. The matrix, around the large phenocrysts, is formed by the small crystals. Phonolite porphyry is the igneous rocks that form Devils Tower. In the Phonolite, the white phenocrysts are made up of feldspar. Smaller black phenocrysts may be made up of augite. These crystals were formed when the magma, that formed the tower and deep underground, cooled slowly. The magma, including phenocrysts, moved upward until about a mile below the surface, and then formed the rest of the crystals. The rest of the magma cooled quickly, at cooler temperatures, and formed the aphanitics. Aphanitics are gray rocks, with fine-grained texture, around the
phenocrysts.
The scientific method applies to Devils Tower. The hypotheses for how the tower was formed, suggest that rocks were cooled and then hardened about 1.5 miles underground. The tower was exposed when erosion removed soft sedimentary rock around the hard igneous rock.
Devil Tower stands 867 feet from base to summit, and above sea level its elevation is 5,112 feet and around 1,267 feet above the north-flowing Belle Fourche River. Sedimentary, igneous, and erosional processes led to the formation of Devils Tower National Monument. First, sedimentary rocks in layers, which are nearly two miles thick, were deposited. About 500 million years ago, most of the layers were deposited in shallow seas. Igneous activity then created the tower until erosional processes exposed it.
The Black Hills region, which is an elliptical dome, was formed …show more content…
through tectonic processes; the rocks were uplifted, fractured, and faulted. The oldest rocks, which are located at a high and central part of the dome, have been eroded the most. Precambrian granites at Mount Rushmore National Park contain older rocks, whereas Triassic Jurassic sedimentary rocks contain younger rocks with less erosion. Younger rocks are more along the edges of the dome. Granites are igneous rocks, in which they have formed from magma that cools below Earth’s surface. Sedimentary rocks form from the consolidation of sediment.
Magma welled up into the older sedimentary rocks, about 50 million years ago. One of the magma bodies became Devils Tower. The magma cooled underground and never reached the surface, which remained buried under sedimentary rock that was more than a mile for many millions of years. The entire Rocky Mountain region was uplifted above sea level, about 5 million years ago, which made the rivers flow aggressively, down into soft sedimentary rocks. Eroded material were carried away and deposited into the Gulfs of Mexico and California. Soft sedimentary rocks, that covered the Tower, were removed by the Belle Fourche River. Igneous rock of the Devils Tower was exposed at the surface.
Layers of sedimentary rocks are formed by mud, sand, and other sediments at Earth’s surface, and are deposited in environments, such as oceans, rivers, and deserts. Solid rock is formed when layers of sand and mud become buried and the weight of additional, overlying material compress mud and sand. Sedimentary rocks are indicators of ancient landscapes, because they begin to form at Earth’s surface. Usually underwater and in layers, the oldest sedimentary rocks are on the bottom while the youngest rocks are on top. Sandstones form cliffs and ledges, because they are harder and more resistant than mudstones. Mudstones form soft and crumbly slopes.
Mudstones and sandstones are named based on their grain size; in the depositional environment, this is an indication of the energy of the currents. Sandstones have a high energy environment, because fast currents are strong enough to move large grains of sand and gravel. Stream channels, windy deserts, and ocean beaches may have currents from high energy environments. Deep Ocean, lakes, and swamps have deposits from mudstones. Mudstones are made up of fine, silt and clay size grains. A particle that is finer than sand and coarser than class is called silt. Fine-grained sediments or soft rock that contain clay-size or colloidal particles is clay.
Fossils, which are remains and traces of past life, are mostly made up of sedimentary rocks. Fossils provide information, such as where sediments have been deposited in an environment. A rock that contains corals and other marine fossils are remains of the ocean environment. Land environments may contain dinosaur fossils. Fossil pollen and other clues are documented to determine the type of environment the organism died at.
The Spearfish, Gypsum Springs, and Sundance formations are three different sedimentary rock layers that are exposed and can be seen along the Red Beds Trail at Devils Tower. Spearfish Formation, of sedimentary rocks, contains the oldest rocks. Spearfish Formation was named after Spearfish, South Dakota. The formation contains layers of bright, red-colored mudstone at low elevations. In the formation, white layers contain a mineral called gypsum, in which is composed of calcium sulfate with two molecules of water. Drywall is made up of gypsum. Gypsum forms when a white crust is left behind when saline water is evaporated in hot, dry conditions.
Approximately 240 million years ago, during the Triassic time, the Spearfish Formation was deposited. During this time, North America, South America and Africa were joined together near the equator; therefore, the Atlantic Ocean and Gulf of Mexico had not formed yet. Triassic age rocks contain the oldest dinosaur fossils.
Mudstones and very fine-grained sandstones make up the Spearfish Formation. On a flat, hot desert plain near the ocean, a fairy low-energy environment had deposited the Spearfish Formation. Iron forms a rusty, red color in sediments. In a hot, dry desert climate, iron was oxidized. Sediments would “rust”, as a result from them being moistened and then dried repeatedly.
Above the red rocks of the Spearfish Formation, contains Gypsum Springs Formation, which only appears as a thin white layer. The mineral gypsum is mostly made up of Gypsum Springs Formation. Gypsum is soft and easily erodible, and forms when saline water evaporates in hot, dry climates, such as the Gypsum Springs Formation. This formation was formed about 150 million years ago, during the Jurassic Period . North America, South America, and Africa began to separate, and form the Atlantic Ocean and Gulf of Mexico. Dinosaur tracks have been discovered in the Gypsum Springs Formation.
The Devils Tower is located in a coastal desert, whereas Death Valley lay in an inland desert environment. The process of gypsum forms is the same in both of these areas. Before the Rocky Mountains had formed, Devils Tower existed on a desert shoreline. During the Jurassic period, Devils Tower area would have been flat, hot, and not mountainous.
The youngest sedimentary rocks are contained within the Sundance Formation. Both a mudstone and a sandstone layer exist within this formation. The gray slope of Stockade Beaver mudstone is under the Yellow Hulett Sandstone that has formed a cliff. The sandstones at this formation at the Tower were deposited from waves that left ripple marks frozen into the sand on a Jurassic coastline.
Sundance Formation is Jurassic age. Africa and South America moved away from North America; the Atlantic Ocean and Gulf of Mexico formed. A shallow sea, called the Sundance Sea, was where deposits of the Sundance Formation formed. During this time period, the sea covered a lot of the Rocky Mountains; Devils Tower was submerged. Near the shoreline in shallow water, and close to a sandy beach was where the Hulett Sandstone was deposited. Farther offshore, in quieter water was where the Stockade Beaver underlying mudstone layer was deposited.
Dinosaur tracks are located throughout the Sundance Formation, when they walked across a shallow tidal flat that was covered with algal mats. Algal mats contain various species of algae. During photosynthesis, the mats produce gasses that cause the mats to rise to the surface. This layer at Devils Tower contains the most fossils, such as oyster shells and remains of fossil squid called belemnites.
Above the Sundance formation, more than 7,000 feet of younger sedimentary rocks were deposited over the next 100 million years. Younger rocks were removed by erosion, but have been preserved in the Powder River Basin. Material from erosion, during this episode, is equivalent to five times the height of the Sears Tower that is located in Chicago.
How fast magma cooled can be determined by the size of crystals in igneous rocks. Crystals have a long time to form and can grow largely when magma cooled deep underground. This can trap heat, because it can be insulated by overlying layers. Intrusive igneous rock is the result of this formation. Crystals that are large enough to see with the naked eye are called phaneritic. Crystals that do not have time to grow large form when magma cools quickly that has exploded or flowed onto Earth’s surface. This is called extrusive igneous rock. These crystals cannot be seen with the naked eye, and their texture is called aphanitic.
It may take tens of thousands or millions of years for a large mass of magma to solidify.
Large crystals, that contained molten lava and change environments by moving into an area with lower temperatures, would cool quickly. A porphyritic texture is where large and small crystals are embedded; therefore, porphyry contains this texture. The matrix, around the large phenocrysts, is formed by the small crystals. Phonolite porphyry is the igneous rocks that form Devils Tower. In the Phonolite, the white phenocrysts are made up of feldspar. Smaller black phenocrysts may be made up of augite. These crystals were formed when the magma, that formed the tower and deep underground, cooled slowly. The magma, including phenocrysts, moved upward until about a mile below the surface, and then formed the rest of the crystals. The rest of the magma cooled quickly, at cooler temperatures, and formed the aphanitics. Aphanitics are gray rocks, with fine-grained texture, around the
phenocrysts.
The scientific method applies to Devils Tower. The hypotheses for how the tower was formed, suggest that rocks were cooled and then hardened about 1.5 miles underground. The tower was exposed when erosion removed soft sedimentary rock around the hard igneous rock.