Mowry Shale

The Mowry Formation fossils are over 98 million years old.

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Scenic View/Photo Spot

The Mowry Shale is easy to overlook today, despite its fascinating history. Look for the silvery gray mounds of shale rock between the prominent ridges of the Muddy and Frontier sandstones. The older Muddy Sandstone contains 100 million year old beach sand stained bright orange and yellow by iron-rich minerals. The younger Frontier Sandstone, formed from 90 million year old beach sediments. Along the coast of an ancient sea, volcanoes (near the present California/Nevada border) spewed ash which fell into salty waters. By studying minerals decaying in the shale, geologists determined that the ash was deposited between 99 and 97 million years ago. The ash likely killed most of the fish swimming here. Currents at the bottom of the sea then scattered their scales. Look for tiny, shiny gray-to-golden fish scales fossilized in these rocks. Taking the time to discover even the tiniest of fossils can bring ancient ecosystems to life in our imaginations.