Fossil Lab: Grand Canyon A Little Photo Gallery from the Canyon. A Little Bit About the Canyon The Grand Canyon started forming 1,630 million years ago with the deposition of the Vishnu Schist (the bottom layer of the canyon) Over time the Colorado River cut into the rock layers forming the canyon. this section of rock is about 200 feet high. Each layer is deposited one on top of the other. Law of Superposition Layers that are at the bottom are the oldest Layers that are at the top are the youngest As time passes, the rocks broke apart (weathered) and created debris piles at the bottom of the canyon. The hardness of the rock layer determines how it weathers. The softer rocks (shale) weather more and create gentle slopes The harder rocks (limestone and sandstone) create steep cliffs Throughout the canyon fossils of organisms were preserved as each layer was deposited. Just like the rock layers, the fossils at the top of the canyon are the youngest and fossils at the bottom of the canyon are the oldest. Layers of the Canyon Know The Canyons History, See Rocks Made By Time Kaibab Limestone Toroweap Formation Coconino Sandstone Hermit Shale Supai Formation Redwall Limestone Mauv Limestone Bright Angel Shale Tapeats Sandstone Layers of the canyon Key to the rock layers Rocks layers deposited Million years ago Fossil Lab Directions 1.Sort the fossils according to which layer A G it belongs to. 2.Get a white board for laying out the layers 3.On your white board draw layers for A G with A at the top and G at the bottom 4.Place each fossil within the appropriate layer. 5.Carefully examine the structure of the fossils, noting similarities and differences of those from different rock layers. Look for trends and arrange the fossils to best reveal those trends. 6.Draw arrows on the white board to show the possible relationships from one layer to the next.