Uwharrie Exfoliation EarthCache

WARNING: The slope you will traveling has lose rock and can slide.  Go to this site at your own risk.  Dangerous sections exist at this location.

To log this earthcache, send an email with the following information.

1. Exfoliation, GC4ZM37
2. Estimate the angle the exfoliated rock dips.
3. What direction does the exfoliated rock face?

The location you currently stand is the heart of a very ancient mountain.  When the earth formed, scientists think most of the surface was relatively flat and was covered by a shallow sea.  Pressure inside the molten center of the earth caused cracks in the crust and the surface started moving.  These huge sections of cooled crust are called tectonic plates.  Over time, magma seeped through the cracks and added more cooled material.  Over time, dry land formed, separating the seas becoming oceans. The dry land formed continents.  Continental crust is less dense than crust below the ocean.

These moving tectonic plates slowly collided with each other.  As they pressed against each other, several things happened:

1. Because ocean plates are more dense, they were pushed below continental plates.  This caused continental plates to be lifted higher above the oceans and coastal mountain ranges were formed.
2. As two ocean plates collided, they caused ripples and tears in the ocean floor.  These create the great trenches and undersea mountains.
3. As two continental plates collide, since they are similar density, they push up making great folds in the crust and continental mountain ranges. 

The spot you are standing is part of the North American plate.  Over 250 million years ago, the North American plate was pushing against the European and African plates.  The resulting push created the highest mountains the earth has ever seen.  Then, for some reason, these plates started to push apart.  The mountains stopped growing and were now subject to the changing seasons. 

Over the next 250 million years, the earth warmed and cooled several times.  During that time over 7 ice ages covered the planet.  These extreme weather shifts caused the mountains to wear down and erode.  As a result, the spot you are now standing was once the very center of a mountain.  The exposed rock is subjected to temperature shifts each and every year. 

Warm things expand. Cool things contract.  This applies to the rock you are standing.  During the summer months, the exposed rock gets very hot and expands.  This expansion loosens the surface layer from the bedrock below.  During winter months, this rock contracts from the extreme cold.  This expansion and contraction causes exfoliation.  The exfoliated surface rock is now loosened and can slide down the slope. As the rock slides, it further breaks up and eventually turns into soil.

The newly exposed rock is now subjected to the same temperature swings as the rock that just fell.  This process happens year in and year out and is one of the many forces that have worn down the mighty Uwharrie Mountains to what you see today.