page_title: Gildersleeve Mountain
section_title: Geology
hierarchical_section_title: Gildersleeve Mountain / Natural history / Geology
caption_attribution_description: English: Picture by H. Petruschke, June 2006. Released to public domain with request for credit.
context_page_description: Gildersleeve Mountain is a summit located in Kirtland, Ohio, United States.
  Gildersleeve Mountain is interesting and important because it is within one of the largest and most densely populated metropolitan areas in the United States. It is a relatively unspoiled and unique area just 18 miles from downtown Cleveland. While this is not unique in a region where urban and suburban forest preserves abound, it is one of only two natural areas with higher elevations and unique rock outcroppings. Little Mountain, which is near the Holden Arboretum, is similar to Gildersleeve Mountain but is accessible on guided walks only. Gildersleeve Mountain is located in the Chapin Forest Reservation of Lake Metroparks and is referred to as the "scenic overlook".
context_section_description: Around 380 to 300 million years ago the area was on the Earth's equator as a part of the Pangaea super continent. With the uplifting of the continental plate, the area went from continental shelf to shallow sea. The geology of the area reflects this transition.
  The lowest visible bedrock is Chagrin Shale. Named for the Chagrin River and easily found in the river valley, Chagrin shale is blue-gray in color, an offshore alluvial, silt shale of the Devonian period. This layer is found below about 800 feet (240 m) msl and is found when drilling wells on the slopes of Gildersleeve Mountain.
  The next layer is Cleveland shale. This is a black shale that is an important source of local fossils. Again Cleveland shale is not visible on Gildersleeve Mountain but can easily be found in the nearby Chagrin River valley between 800 and 900 feet (270 m) msl.
  Bedford shale is found above the Cleveland Shale layer. This material marks the uncertain transition between the Devonian and Pennsylvanian periods in the region. This layer is found in the ravines that run off the slopes of Gildersleeve Mountain. Bedford shale is a sand shale and is characterized by its roughly 90° cleavage pattern. Pieces of Bedford shale can look as if they were cut by human hands and are found up to about 950 feet (290 m) msl.
  A thin strata of Sunbury shale is often found above the Bedford Shale. This is a thin layered, black shale, of more silty origins, possibly from a period when the waters running into the ocean basin were running slower, creating finer particles.
  Berea sandstone is found from around 950 feet (290 m) msl to roughly 1,070 feet (330 m) msl. However, at this point it should be mentioned that the rock structure around Gildersleeve Mountain is by no means uniform. Millions of years of glaciation and resulting erosion and fill have resulted in many ravines that have been subsequently filled with glacial till and alluvial clays. Still, Berea sandstone is found in outcroppings and in other areas on Gildersleeve Mountain. In the nineteenth century it was quarried from the Stannard Quarry, what is now Quarry Pond, near Chillicothe Road. This material was used to build Kirtland Temple and other local structures. Berea sandstone is still used as a local building material.
  Sharon conglomerate is found beginning around 1,070 feet (330 m) msl. It is the predominant outcropping on Gildersleeve Mountain. Sharon Conglomerate is a sandstone imbedded with white quartz pebbles. It is hypothesized this rock was created by fast-running streams, running down ancient mountains. Faster-running water carried larger pebbles along with the sand, and this was deposited very near shore, or in river or stream deltas and estuaries. It is Sharon conglomerate outcroppings that up make most of the spectacular ledges that are found on the southeast, north, and western sides of Gildersleeve Mountain. The ledges have been split and eroded to create up to three distinct sets of formations separated by deeper crevasses. In some areas, there are vertical faces of over 30 feet (9.1 m) with very steep slopes at the base. In these areas the elevation change is dramatic, going from 1,060 feet (320 m) to 1,130 feet (340 m) in under 150 feet (46 m) of horizontal distance.
  As mentioned earlier, glaciation has played an important part in the geology of Gildersleeve Mountain. During the Wisconsin glaciation, ice sheets more than a mile thick covered the region. Glaciers are the major erosive force in the region and ground down the higher elevations while scooping out the [Great Lakes]. The hard Sharon conglomerate is more resistant to this grinding action.
  Glacial ice is not the only erosive force to act upon Gildersleeve Mountain. Glacial melt released huge amounts of water that flooded the landscape. This water cut ravines and filled others with clay and rocky debris.
  The Gildersleeve Mountain we see today is the result of hundreds of millions of years of erosion. The sedimentary rocks were created by ancient erosion of the land, and the worn-down relic of a higher peak is also the result 
caption: A rock face of exposed Sharon conglomerate
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