This layer averages about 335 million years old and is composed of marine limestones and dolomites. This is probably the most prominent rock layer in the Canyon as it usually 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. The only way though this barrier is in areas where the rock has faulted and broken apart to form a slope which can be climbed upon. The deep reddish color of this layer is caused by iron oxides leaching out of the layers above it and staining its outward face. Behind the reddish face the rock is a dark brownish color. Numerous marine fossils can be found in the Redwall Limestone including brachiopods, clams, snails, corals, fish and trilobites. Many caves and arches can also be seen in the Redwall.
 
Grand Canyon Rock Layers
 

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