Stebbins Gulch Lower Stratigraphy

    The stratigraphic units of lower Stebbins Run

At this point the creek bed is floored by a resistant siltstone that forms a pavement-like surface for over 100 feet along the approach to the lower waterfall. The siltstone “floor” is part of the Chagrin Shale, as are the eight feet of red-tinted claystone and blue-gray shale above it. Continuing upwards, the dark gray, younger, Cleveland Shale comes next.  The dark color indicates that it accumulated in stagnant, oxygen-depleted conditions on the sea bottom. Incomplete decomposition allowed organic matter to accumulate in the sediments. The Cleveland Shale is an oil shale, containing significant amounts of a waxy hydrocarbon called kerogin. All the marine sediments seen here are part of the 370-million-year-old, 650-foot-thick Ohio Formation. The outcrop is topped with a thick layer of glacial till. Till is  a loose jumble of boulders, cobbles, pebbles, sand, silt and clay  deposited by melting glaciers some 10,000 to 12,000 years ago over two-thirds of Ohio. Imagine what would happen if the forest were suddenly clear-cut from the steep slopes above the creek. Enormous amounts of sediment would immediately start eroding into the creek, with profound implications for the water clarity, temperature and biodiversity of the stream.

     
Return to Stop 5