Stebbins Gulch Siltstone and Shale

Thin-bedded Siltstone and Shale

The outcrop shown here is part of the Bedford Formation, and shows a typical sequence of buff-colored marine shales interbedded with occasional thin layers of tan-to-yellowish siltstone and fine-grained sandstone. This is a change from the thick layers of shale in the underlying Chagrin and Cleveland units that we see near the lower waterfall. The Bedford Formation directly overlies the Cleveland Shale. We cross the contact between the two units about 0.32 miles up the creek, measured from the lower waterfall. The thin beds of siltstone contain much larger sediment grains than the shale layers, and may represent occasional storms and flooding off the delta where these sediments were deposited. The increasing  number of siltstone beds in the Bedford Formation also explains the sudden increase in small waterfalls and cascades that we encounter after crossing the contact between the Chagrin and Bedford units. Each of the siltstone beds is capable of forming a caprock for a small waterfall, thanks to the less resistant shales above and below it.

     
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