These formations, known as the Cincinnatian Series, are approximately 200 meters (600 feet) thick and are composed of alternating thin to very thin bedded, gray, fossiliferous limestone and blue-gray ...

Mudstone, shale, and limestone are examples of sedimentary rock likely to contain fossils. As the layers of sediment build up on top of one another, they create a physical timeline. The oldest layers, ...

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A shallow sea advances and retreats several times during this period, leaving behind the layers named Kaibab Limestone, Toroweap Formation, and Hermit Shale. The Coconino Sandstone layer was ...

A sandstone and shale cap, as thick as 50 feet in places, acts as an umbrella over limestone ridges. The umbrella leaks at places called sinkholes, from which surface water makes its way ...

and shale and limestone mountains. This is a land where elk, moose, wolves, and bighorn sheep roam almost as freely today as ...