TNRIS has a great general USGS map of the area in and around Big Bend with many of the natural features referenced in this forum labeled. The topography map isn't sufficiently detailed for hiking but is a great reference for those who want to track the geologic features and locations discussed around here.
http://www.tnris.state.tx.us/datadownload/quad.jsp?Quad=Persimmon%20Gap&num=29103-F2I scrolled down and downloaded the 250K Collared DRG. You can open with a photo program, then zoom in and around!
Al
P.S. I forgot to mention there are several files in a zip file. Open the image file first.