[ETL]

Did you ever look up at the top and see the layer about four feet below the surface, you know with just a little dirt and grass on it and observe that it is just as hard as the stuff at the bottom?

That's most often an erosionally truncated surface of rock. ie, it *was* at one time deep beneath the surface under great pressure. What was once above it is no more.

[ETL]

"it *was* at one time deep beneath the surface under great pressure. What was once above it is no more."

To follow up, often an erosionally truncated surface can be correlated with identical rock layers at another location where the overlying (younger) rock layers are still present. The Catskills are loaded with such examples. (I see from your About page you're from the New York area as well).

And since you recommended some books, here are a couple I recommend. Sorry, they don't have one for Joisey:

http://geology.com/store/roadside-geology-new-york.shtml

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http://geology.com/store/roadside-geology-pennsylvania.shtml