Grand Canyon Research Paper

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Pages: 3

Most of the rock in the Grand Canyon is composed of sedimentary rock. The three main types of sedimentary rock that make up the Grand Canyon are sandstone, shale (or mudstone), and limestone. The rock layers that formed during the Paleozoic Era are the most visible in the Grand Canyon’s walls. Coastal environments and several marine incursions from the west between 550 and 250 million years ago deposited sandstone, shale and limestone layers totaling 2,400 to 5,000 feet thick.
Kaibab Limestone layer, the current top of the Grand Canyon, ranges in color from cream to a greyish-white, averages about 250 million years old, and is composed primarily of a sandy limestone with a layer of sandstone below it. Toroweap Formation layer averages about
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Hermit Shale layer is a deep, rust-colored red, averaging about 265 million years old and is composed of soft, easily eroded shales which have formed a slope. As the shales erode, they undermine the sandstone and limestone layers which causes huge blocks to fall off into the lower reaches of the Canyon, and many of them end up in the side drainages and down on the Tonto Platform. Supai Formation layer varies from red for the shale to tan for the sandstone caps, averages about 285 million years old, and is composed primarily of shale that is mixed together with some small amounts of limestone and covered by sandstone. The limestone features become more prominent in the western regions of the Canyon, which suggests that that region was more marine. Redwall Limestone layer averages about 335 million years old and is composed of marine limestones and dolomites. The deep reddish color of this layer is caused by iron oxides leaching out of the layers above it and staining its outward face. This rock layer forms a sheer cliff ranging from 400-500 feet in height, which has become a natural barrier between the upper and lower regions of the Canyon, making it the most eye-catching layer in …show more content…
This layer occurs irregularly in the eastern Grand Canyon via limestone lenses that fill stream beds that have been eroded into the underlaying Mauv Limestone. Apart from these channels, the Redwall Limestone sits directly atop the Mauv Limestone. In the western regions, the Temple Butte Limestone is quite prominent as it forms massive cliffs hundreds of feet high. Muav Limestone layer is grey in color, averages about 515 million years old and is composed primarily of limestone that is separated by beds of sandstone and shale. The Mauv Limestone layer is much thicker in the western areas of the Canyon than it is in the east. Bright Angel Shale layer is mostly various shades of green with some grey, brown and tan, averages about 530 million years old, is composed primarily of mudstone shale and interbedded with small sections of sandstone and sandy limestone. The retreat of the Canyon rim is accredited primarily to the erosion of this layer which forms the top of the Tonto Platform. Tapeats Sandstone layer, which is dark brown, averages about 545 million years old and is composed of medium-grained and coarse-grained sandstone. Ripple marks formed by ocean waves of an early