Abstract
The Grand Canyon is the second largest canyon in the world. The region has attracted a lot of tourists from various parts of the world for different reasons. Tourists come to this region for many reasons. Some of the tourists are scholars, while others are just holiday makers.
The rocks of Grand Canyon were formed in a number of ways. The sedimentary rocks found in this place have been inexistence for a period of over 2 billion years. Various climatic conditions and environmental factors have reshaped the rocks in this place. Currently, the rocks exist in different layers, with each layer being unique.
Introduction
The Grand Canyon is one of the most visited places in the world due to its wonderful nature. According to Karl, the Grand Canyon is one of the largest tourist’s attractions in the world, drawing attention of both leisure and academic tourists. This scholar observes that this place is one of the most amazing sceneries around the globe.
The rocks, the trees, and the animals found in the Grand Canyon National Park, and the general nature of this place has seen it make visitors come to the region several times. Thayer says that nature at times comes with many wonders. This scholar says that the nature at the Grand Canyon is breathtaking because there are a number of objects which are obviously defying nature.
The nature of this place demonstrates a number of facts about the development of Grand Canyon. There are a number of natural sceneries in North America with some of the amazing features. However, the Grand Canyon presents something special to visitors who either come for leisure or for academic purposes. The caves in this place formed due to a number of natural activities, come in different shapes and sizes. The caves clearly demonstrate the strength of the rocks around it.
The rocks of the Grand Canyon are some of the most beautiful sceneries at this place. Kaiser says that the rocks of the Grand Canyon have attracted the attention of various scholars from different professions. The sedimentary rocks are arranged in beautiful layers of over 40 that are visible when one visits the Grand Canyon National Park. According to Abbott, there are about fourteen unconformities in geologic records which are in Grand Canyon.
These are features that are obviously going against the law of nature. Understanding these rocks will require an understanding of the historical perspective of the development that took place, and which resulted into the sceneries at Grand Canyon. This research is focused understanding the physical and historic geological facts about the Grand Canyon.
The Formation of the Rocks of Grand Canyon
The history of the geology of the Grand Canyon can be traced back to about 2 billion years ago. According to Augustin, a number of scholars have tried coming up with explanations as to how the rocks at Grand Canyon were formed.
Various geologists have studied the fossils found in this place in order to explain the facts about the formation of this place. This scholar says that some of the records about the formation of this place are contradictory. However, recent geologists have come into agreement in some of the facts. The fact that the rocks at Grand Canyon have been in existence for the last 2000 million years is undisputed.
Karl says that during those Precambrian times, substances such as sand, ashes, silt and mud were on the shallow end of marine basin adjacent to the organic belt. In about 1800 to 1600 million years ago, a number of Island arcs came into a collision with proto-North American continents. The plate tectonic processes then condensed and grafted some marine sediment in the basin. The sediments were pushed out of the sea onto mainland. As time went by, these rocks were buried deep under the surface, about 12 miles deep.
This resulted in a massive pressure on these rocks from the weight above them. The result was the formation of metamorphic rock. The resultant is what was named as Granite Gorge Metamorphic Suite which has attracted the attention of archeologists and geologists alike. This granite consists of Metasedimentary Vishnu, and Metavolcanic Brahma which were formed about 1700 million years ago.
During the collision of mainland and volcanic islands, several magma blobs arose from subduction zone, and then intruded into Granite Gorge Metamorphic Suite. The plutons iced slowly, which then formed Zoroaster Granite. Some part of the granite would later form metamorphosed gneiss. This is visible currently when one is studying these rocks as bands with a light color. According to Thayer, this intrusion took place in three phases. In the early Vishnu age, there were 2 phases of this intrusion.
The third intrusion came much later in about 1400 million years ago. This phase experience a massive faulting, specifically along the south-north faults. This led to a partial rift of the continent. The collision would then lead to the extension of this continent, from Wyoming-Colorado borders to Mexico, nearly doubling-up the depth of the crust in the entire region of Grand Canyon. This was how the ancestral Mazatzal Mountains which is about 10 kilometers high was formed.
Then subsequent erosion came, which lasted about 300 million of years. This erosion swept away sediments of the mountain. The consistent erosion of the mountains over a span of several years resulted in reduction of the height of the mountains, and after a while, the high mountains were turned into small hills which are barely ten meters high.
According to Kaiser, two main factors have contributed to the formation of rocks within this country. About two million years ago, the climate in this region played a major role in the formation of rocks of the Grand Canyon. The region was very wet all through the year. This scholar describes this as the ice age which was about 2 million years ago. During this time, excavation at the Grand Canyon was very high, which dug it deep as it stands now. The figure below shows some of the excavated site at the Grand Canyon.
This figure shows the activities of nature that has resulted in a massive excavation of the sedimentary rocks formed about 1800 millions years earlier. The wet weather meant that there was a constant flow of water during most part of the year. The figure above shows a ridge formed due to constant flow o water. The figure clearly demonstrates the power of water in motion in the development of some rocks. The movement of water started off by washing away the top, soil which could easily be swept away.
As the top soil was washed away, the sedimentary rock that had been formed due to the cooked-pressure remained exposed to the flowing water. This movement of water on the rock slowly excavated the rock over hundreds of millions of years. The first step would be to soften the rock. When the rock was made soft, it became easier for some of its particles to break off, and with time, the erosion became deeper and bigger. As Karl explains, the flowing water would form a path.
The figure above shows a path of water that can be clearly be stated as the main agent of the erosion of the sediments. Other parts where the water has not formed its path have remained higher. As the rock particles fall into the moving water, they are always swept off into downer parts of the stream. As they move in this water, they come under constant collision leading to their further breakage.
They decrease in size, and lose their original shapes. The vegetation is another natural factor that has had impact in the formation of the rocks. The sedimentary rocks can be strong enough to withstand the flow o water for a very long period of time. However, when there are vegetations on the rock, some of the roots would crack the rocks as they penetrate into the soil.
When the rock is crack, it becomes easy for water to penetrate into the rock and cause further erosion of the sediments. Earth quake forms another agent of the breakage of the rock in this region. The region is still prone to massive earthquakes which create cracks on the rocks. Mass wasting erosions still affect the regions, leading to further breakage of the sedimentary rocks.
Human activities have affected the rocks of the Great Canyon in two main ways. At first, activities of human accelerated the excavation of the sedimentary rocks. During those early years, farming was not practiced. However, hunting and gathering wild fruits were common. This could also involve digging deep into the soil to get some of the roots that were either considered as medicine, or fruits.
This digging was part of excavation, and when water swept such surfaces, erosion would be inevitable. As men became more sophisticated, farming became important. Farming also had an increasing effect on the excavation of the rocks. It was easier for the soil on the farms to be swept off. By the end of Pleistocene ice age nearing the onset of the Holocene, the climatic condition of this area began to change.
This was majorly due to human activities. The climate of this area was changing from a cool and wet pluvial climate, to a semi-arid climate. The area is currently a semi-arid. With the conditions getting drier, water erosion on the rocks became less. However, mass wasting was on the rise. Several cliffs became stiffer, making the Grand Canyon and tributary canyons wider. Mass wasting was reducing rocks in this canyon, as the debris fell off and was swept into Colorado River in a gradual and consistent process.
As modernization came to effect, people realized the importance of preserving these sites. Upon the realization that the sites were important, people came up with strategies that would help preserve these places. Building of dams have significantly minimized capability of Colorado River (which was one of the leading excavators of the canyons) to dig out the rocks Grand Cantons.
It has totally changed the pattern of movement of sediments, and their deposition. Glen Canyon Dam was constructed to control floods in order to bring a restorative effect on the Canyons. Animals, both domesticated and wild animals also play a vital role in the developments of the rocks at Grand Canyon.
Every animal, both carnivores and herbivores play an important role in the development of rocks. When these animals walk within the Grand Canyon National Park, they break particles of the rock. This is especially so to the large herbivores with hooves which have the ability to break rocks into smaller particles. These herbivores also eat the vegetations that cover the soil. This leaves the soil bear, and when rain comes, it easily erodes the rocks.
The Composition of the Rocks of Grand Canyon
According to Abbott, understanding the composition of the rocks of the Grand Canyon may be interesting process. This geologist and a scholar say that the rocks of Grand Canyon have been in existence for a period of over 70 million of years. The plate tectonics on the North American continents and other adjacent island caused collision, and this was the genesis of how the rocks in this place started forming, as explained above.
As time went by, several activities, mostly natural process accompanied by some human activities, resulted in a massive erosion of the rocks, and the result is what we have today; different layers of rocks on top of one another forming the current Grand Canyon. The figure below shows the composition of the rocks of the Grand Canyon.
The figure above shows rocks arranged in a strata, with each stratum having a particular layer of rocks having different years. The layers are as follows.
Kaibab Limestone
This is the top most layers in the strata. According to reports given by Thayer (29), this layer is over 250 million of years old. The Kaibab Limestone has formed the surface of Coconino and Kaibab plateaus. In this stratum, the composition of the rocks is mainly sandy limestone, with a huge layer of sandstone under it.
Shale and sandstone subsist as upper layers in a number of places, particularly the upper regions of the cliffs (Abbott 94). The color of this layer is ranging from grayish-white to cream, depending on a number of factors. Abbott (26) notes that the layer has a strong resemble with a bathtub ring, and so the layer was named Canyon bathtub ring.
This scholar says that geologists have stated that this ring was curved in a way that may give the impression that the process was influenced by activities of human being. Besides the rocks stated above, some fossils also form composition of this layer. This includes the sea lilies, the corals, mollusks, and some brachiopods (Abbott 22). Fish teeth and worms also form part of this layer.
Toroweap Formation
This is the second stratum. This stratum is about 255 million of years old. This layer was formed through a pretty similar process as that of Kaibab Limestone above, but as time went by, it was pushed down due to the formation of the Kaibab Limestone. The composition of the rocks in this layer is similar to that in the Kaibab Limestone. Their fossil history is almost the same, only that the worms and fish teeth found in Kaibab Limestone are very minimal in Toroweap Formations. This layer is dark in color. The color ranges from grey to yellow.
Coconino Sandstone
The formation of this layer was in about 260 million of years ago. The rock composition in this layer is different from that of the above two layers. In this layer, the main composition of the rocks is pure quartz sand. According to Kaiser (59), these are essentially petrified sand dunes. This scholar also states that this stratum has a wedge shape cross bending, which is visible in places where the traverse section of the layer can be seen. In this layer, the color ranges from cream to white colors (Abbott 83).
Although archeologists and geologists have tried to study the rocks in this layer, skeletal fossils are yet to be found here. This may be an indication that this layer could not have supported life. However, the geologists and archeologists are still studying this layer for further investigation because a number of invertebrate tracks, and some fossilized burrows have been discovered.
Hermit Shale
This layer has been in existence for about 265 million of years. In this layer are the soft and easily eroded shale rocks (Karl 45). They have formed a slope. The weakness of this layer has been the main agent of mass wasting of these rocks. Because of this weakness, the rocks in this layer easily break off, undermining the sedimentary rocks in the above layer.
This makes it easy for this layer, and layers on top of it to fall off into the drainage in the lower canyons down into Tonto Platform. In this layer, the color is rust-colored red. The fossils in this layer include conifers, ferns, and other plants. Also discovered were fossilized tracks of amphibians and reptiles.
Supai Formation
This layer has been in existence for about 285 million of years. The layer mainly consists of shale which is mixed up with limestone capped together by sandstone (Thayer 48). In the western part of the Canyon, limestone features are more prominent (Augustin 29). Geologists have associated this by the possibility that this side could have been a marine as opposed to the eastern part. In this layer, the color ranges from tan for sandstone caps, to red for shale (Abbott 46).
On the eastern section, there are a number of fossils of the reptiles, the amphibians and some terrestrial plants, whilst on western part are the marine fossils (Thayer 19).
Redwall Limestone
This layer has been in existence for about 335 million of years (Karl 87). The main composition of this layer includes dolomites and marine limestone. According to Augustin (65), the Redwall limestone is the most prominent of the Canyon layers forming a cliff of about 400-500 feet high.
This layer is a barrier between upper canyon and the lower parts of Canyon. Though various earth movements, this layer cracked in some regions, breaking the barrier between the upper and lower parts of the canyon. The rock is brown in color. However, due to the presence of iron oxide, this layer appears to be red. Some of the fossils in this layer include corals, fish, trilobites and clams (Augustin 34).
Temple Butte Limestone
This layer has been in existence for about 350 million years. In the eastern part is dolomite; while to the west is freshwater limestone. The rocks in this layer are irregular. This may be due to the erosion of the Mauv Limestone. The layers are also very prominent, which then forms a cliff of great heights of several hundreds of feet (Karl 67). The colors of the layers range from grayish cream to the west, to purple on the east.
Tonto Group.
The rocks in this layer have been in existence for over 515 million of years. These layers differ in color and composition. Vishnu Schist forms the base of the Grand Canyon
Conclusion
The Rock of Grand Canyon is one of the geographical wonders around the world. The rocks have attracted a number of geologists who have developed interest in understanding how the formation of the rocks was. The formation of the rocks was heavily influenced by a number of climatic conditions. The initial rocks of this place were ingenious rock. This changed after a long period of natural activities. The rocks of The Grand Canyon are mainly sedimentary, having been formed due to weathering process of the initial rocks.
References
Augustin B. The Grand Canyon. New York, Marshall Cavendish Benchmark, 2010.
Kaiser J. Grand Canyon: the Complete Guide. Ringgold: Destination Press, 2011.
Karl K. Grand Canyon Geology: Two Billion Years of Earth’s History. Boulder: Geological Society of America, 2012.
Stanley S. Earth System History Third Edition. New York: Clancy Marshall, 2009.
Thayer D. An Introduction to Grand Canyon Fossils. New York: Grand Canyon Association, 2009. Print.