Quote:
Originally Posted by jjone20
That would be the Appalchian Mountain chain. Formerly mountains as high or higher than the Rockies. Formed by continental drift millenia ago, and since eroded to their current form. The curve is caused by the distortion of colliding plates and different rock composition. In a nutshell...
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I can expand on this.
This question would have been right out of one of my geology midterms back in the early Holocene at UCSB. The essay answer would be longer than what I will bore you with here.
When the early Appalachians were formed during the collision between Africa and North America, the sedimentary rocks were folded and uplifted to mountains that would have looked a lot like the Alps today. Then the two continents moved apart, ending the episode of uplift.
The large mountain chain then eroded. The contorted layers of sedimentary rock eroded at different rates. Harder sandstone layers stand out. The folding created plunging anticlines and synclines. A plunging fold is a fold whose fold-axis is not horizontal. When you erode plunging folds, you end up with U-shaped features in map view. This is what you've got here.