The Grand Canyon: Geology
The Grand Canyon, with its many layers of sediment, tells a story as old as 2 billion years. Chronologically, the layers fallow the Law of Superposition (youngest rocks on top, oldest on bottom). In toltal one would see 9 distinctive layers that give us evidence to how and what was going on millions of years ago.
The first layer of sediment dating back 250 mil years ago existed during a time where the area was submerged in water. This is evident by its Kaibab limestone formations and marine animal fossils. Going a layer down we find evidence of what the GC was like 260 million years ago. Cocoino sandstone shows evidence that the Grand Canyon was above sea level with footprints of vertebrate animals confirming. If we go further, we start uncovering 265 million year old Hermit shale and land dwelling animal fossils. This shows during this time the grand canyon was still above sea level. Go another layer down and we hit the 285 million year old Supia Formation. This layer was a mix of both sheals and limestone's which makes it hard to tell weather or not it was or was not above sea level. However, due to the larger amounts of limestone scientists believe it to be more of a marine layer. The next layer is around 320million years old. Its a layer of Redwall limestone that is roughly 500ft high and typically drops at a 90 degree angle. This layer, due to its limestone nature and fossil content was created during a time of submergence. The next three layers make up the layer grouping labeld as the Tonto Group. The youngest layer of this group is The Mauv limestone formation, found below redwall limestone and they too were created while underwater. Trilobite fossils are abundant here. below the Muav we find a layer of Bright Angle Shale signifing the grand canyon was abouve sea level
The Grand Canyon has been transforming the last 2 billion years, in fact, its still transforming. From its depth to its width, water levels and general...
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