Geology - South of Shenandoah

[PaddyBeer]

I assume the glaciers did not get down to the southern end. I was wondering if anyone could explain the presense of the large boulders atop the mountains from mid VA south.

Thanks,
Kevin (Paddy)

[The Old Fhart]

PaddyBeer, Google "tectonic plates" or click here. I believe there is a good book on geology available from the ATC as well.

Walking thru VA you can see how the plate on the Atlantic side rode over the inland plate creating the cliffs that overhang toward the west. Tinker and McAfee are good examples.

[stupe]

Paddy,heres my two cents........ north of the limit of the last glacier you find glacial erratics, non local rock dragged by the glacier from further up north, sometimes ending up on mountain tops. But theres more than one way to leave a boulder on top of a mountain.
Boulders of local rock settle when wind and water erosion remove all the softer material over, around, and under them. The vast majority of them get washed down into the valleys. But if they have the luck to land on firm bedrock support on top of whats left of the mountain, there they stay.
If it seems unreal, consider that the mountains in the appalachians were heaved up eons ago, and originally were bigger than the present day Rocky Mountains. They were pared down, south of the furthest reach of the last glacier, by hundreds of millions of years of water erosion. Water cut the Hudson River channel over 600 feet deep in some places, and formed the gaps between mountains. Thinking on that large a scale, a boulder on a mountain top is just a pebble on a rock pile.
I remembered all this stuff from college thirty years ago, and I hope I remembered it right.

[TJ aka Teej]

Underfoot: A Geologic Guide to the Appalachian Trail, by V. Collins Chew
Available from the ATC website, Amazon, etc

[PaddyBeer]

thanks folks


Paddy

[hungryhowie]

consider that the mountains in the appalachians were heaved up eons ago, and originally were bigger than the present day Rocky Mountains. .

Not only were they bigger than the present-day Rockies, they were once also larger than the present day Himalaya!

How would you like to have climbed Clingman's Dome back then, eh?

-howie