Here are some good spots to stop.
If you do come out to the Texas hill Country, and you are driving in from the East, I can tell you some good fossil hunting location in East Texas where I have found shells, coral and even a sharks tooth in the sandstone. These East Texas fossils are very recent geologically speaking, and are fragile compared to those in the Central Texas limestone.
More Valley Spring Gneiss info.
This site gives a history of Valley Spring Gneiss and Packsaddle Schist. Here is part of what it says;
“The first sediments were eroded rhyolites and volcanic tuffs, which would later become the Valley Spring Gneiss. These where followed by arkoses eroded from the igneous bodies of the old mobile belt which would become the Lost Creek Gneiss, and, as the mobile belt began to erode to sea level, the sandstones, shales and limestones which were to become the Packsaddle Schist were deposited.â€
Try going on a college field trip with a bunch of nerdy rockhounds (like myself) and see how long it takes before the comments "That is nice Gneiss", or "Oh Schist! (Said like cursing)" get old :)
Space/Science » in reply to I'm gonna bookmark that one, REB.
Some more info Valley Spring Gneiss and Packsaddle Schist