VFEC1: The Talus Slope EarthCache
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VFEC: Valley Forge EarthCache
At the given coordinates you will be standing on the Valley Creek Trail just south of the Upper Forge site. Here you will see one of many talus* slopes located in the 3,500 acres of Valley Forge National Historical Park. They are most easily seen here on Mount Misery and on Mount Joy (across the road to the East).
A talus slope is an accumulation of rock debris at the base of a steep slope. Generally, these are very unstable and inhibit growth of vegetation (other than the primitive nonvascular plants). They are often formed from frost heaving (the expanding and contracting of soil due to reoccurring freezing and thawing), a physical weathering processes that slowly wears mountains down. During non-freezing weather, water flows into cracks and crevices in the rocks. When the temperature drops, the water freezes and expands forming a powerful wedge which eventually breaks out pieces of rock. This repeated cycle can lead to significant erosion. Formation of talus slopes can occur on planets or moons other than the Earth. For example it is fairly common for fresh craters on the Moon to have piles of talus along the base of the inner wall.
Here in Valley Forge, blocks of Chickies quartzite form the slope. It is white on weathered surfaces and dark gray on fresh surfaces. A talus slope is dangerous terrain. The material is sitting at its steepest possible slope, its angle of repose. A small disturbance, such as your misstep, can trigger a slide that may injure or even kill you as you go downhill with it. Also, there is no geological information to be gained from walking on talus.
(*) Scree and Talus are often used interchangeably. Scree often refers to rocks that are smaller than the human head while talus is used for larger rocks. Scree comes from the Old Norse term for landslide.
To log this earthcache, e-mail me an answer to the following question:
Guesstimate the angle of repose on this slope in degrees. (Your answer should be between 5 and 80 degrees).
Sources: http://museum.gov.ns.ca/mnh/nature/nhns/h5/h5-4.htm
http://geology.about.com/library/bl/images/bltalus.htm
http://www.wikipedia.org/
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Valley Forge Caching Info:
It is required that cachers stay on marked trails at all times.
Only Earthcaches and virtual stages of caches may be placed on Valley Forge land.
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Additional Hints
(No hints available.)