This layer averages about 350 million years old and is composed of freshwater limestone in the east and dolomite in the west. In the eastern Grand Canyon this layer occurs irregularly and only then by way of limestone lenses that fill stream beds that have been eroded into the underlaying Mauv Limestone. Apart from these channels, which are quite large in places, the Redwall Limestone sits directly atop the Mauv Limestone. The Temple Butte Limestone is quite prominent, however, in the western regions and forms massive cliffs hundreds of feet high. The color of this layer ranges from purplish in the eastern regions to grey or cream colored in the west. The only fossils to be found in the eastern region are bony plates that once belonged to freshwater fish. In the western region there are numerous marine fossils.
 
Grand Canyon Rock Layers
 

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