![]() Though this bedrock is most exposed in the canyon itself, you can catch glimpses of it nearby: in weathered rock knobs poking through to the land surface, in layered strata exposed along road cuts and in local stone quarries. In fact, the exposed bedrock contains many marine fossils. This rock formation, which lies much deeper under central and southwest Iowa, was deposited as limey mud and shell fragments in a warm, clear, shallow sea that covered the interior of North America about 430 million years ago (Silurian age). The landscape-changing factor in this case is bedrock: durable dolomite-a magnesium-rich limestone. Such eye-catching features in Iowa’s scenery are usually the result of underlying geological conditions. In addition to great scenery, this canyon offers lessons in Iowa geology, both here and throughout the state. Only on near-approach does the sudden, 150-foot drop into this geological gem come into full, spectacular view. ![]() Looking out across the rolling countryside from Highway 151 or county roads, you could miss this canyon all together. Below the canyon, the creek valley broadens again before emptying into the North Fork of the Maquoketa River. The zig-zag course takes nearly three miles to cover a two-mile, straight-line distance. Geological Survey topographic map, identifying a deep, twisting, forested segment of Whitewater Creek.Īs the creek flows from southern Dubuque County into northeastern Jones County, its valley abruptly narrows to a constricted gorge bound by steep bedrock bluffs, a series of sharp turns and tight meander loops deeply entrenched into the surrounding landscape: Whitewater Canyon. The word “canyon” is rare among Iowa place names.
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