"...I didn't either. My friend and I were talking about the fossils we find in his creek gravel in the hills of central KY. They're old, old looking sea shells, and other marine fossils that look like they've been embedded for forever and a day. We were hypothesizing that they were maybe brought there by tsunami or something, but this would make sense.
Does anyone know if they have an estimate for how far inland the waves came?..."
I grew up there (in Clark County), and was a fossil hunter from a very young age; I probably have the same fossils; mostly brachiopods, a few cephalopods, some sea cucumbers, etc. They are of upper Ordovician age (meaning that they are at leat 443 million years old). These fossils have absolutely nothing to do with the Chesapeake crater.
The sea fossils you are finding were deposited when that strata was a marine environment.