Loyalhanna Gorge EarthCache
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The pristine Loyalhanna Gorge which towers over Loyalhanna Creek and Route 30 between Ligonier and Latrobe is owned by Westmoreland County and has been designated as The Loyalhanna Gorge Greenway. The Loyalhanna Gorge is a three-mile-long section of the Chestnut Ridge that has been carved by actions of the Loyalhanna Creek. Elevations around the rim of the gorge rise to 1900 feet. The river gradient drops about 100 feet over this three mile section with gentle pools and boulder-strewn rapids. The topographic crest of the gorge corresponds to the Chestnut Ridge which was formed during the Allegheny Orogeny, 300 to 350 million years ago, when two continents collided to form the Allegheny and Appalachian Mountains. Massive sandstones of the Pottsville Group, (Pennsylvanian age),form the rim, whereas softer, sandy shales of the Oswayo Formation,(Devonian age), are exposed at the river channel. The geologic record of hundreds of millions of years is exposed in the rocks of this gorge. The story of the formation of the Loyalhanna Gorge is one of erosion. Erosion is the process by which material is removed from a region of the Earth surface. It can occur by weathering and transport of solids (sediment, soil, rock and other particles) in the natural environment, and leads to the deposition of these materials elsewhere. It usually occurs by transport due to wind, water or ice; by down-slope creep of soil and other material under the force of gravity; or by living organisms, such as burrowing animals. In order to log this EarthCache, 1. Record the date and time of your visit. 2. Using your GPS receiver,measure the elevation at the posted coordinates. 3. Determine the elevation of the water's surface at the time of your visit. 4. Using your measurements and the information contained in this EarthCache listing, calculate your best estimate of how many years it takes the Loyalhanna Creek to erode one foot of rock from the Chestnut Ridge. Each visitor must email their answers to these four questions prior to logging. Failure to do so will result in deletion. Dave Lentz
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