Geopic of the week: Plunging folds at Gulpha Gorge

Gulpha Gorge_adjusted

Imagine you took a stack of ribbons, compressed it till it buckled into bows, and then tilted the whole stack on its side.  That pretty much sums up what you can see in this picture of plunging, folded bedrock at Gulpha Gorge Campground, north of Hot Springs, in the Ouachita Mountains of Arkansas.  The bedrock of the Ouachitas was buckled and tilted about 200 million years ago when the South American and North American continents collided – part of the incredible process geologists call plate tectonics.

This is just a couple of wee folds that are exposed at the surface because the bedrock at Gulpha Gorge is novaculite – a really hard rock that doesn’t erode away easily.  However, if we could strip the vegetation and civilization away in central Arkansas, we would see that pretty much all the rocks in the region are folded and tilted in similar ways.  Some of the folds cover many square miles and can be seen from space on a clear day, and others are no bigger than a speed-bump. 

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