Birdy, thanks for posting those maps.
I have been reading a couple of primary source books lately, the first being James Gillett's "Six Years With the Texas Rangers". Gillett, like many other first-person historians of the period, describes his travels by geographic landmarks, primarily rivers, watersheds, and heights of land. After pulling my hair out trying to find these locations on standard maps (which are great for highway driving, but suck topographically speaking) I ordered this relief map:
http://www.texasmapstore.com/Texas_Raised_Relief_map_p/topo005.htmIt ain't here yet, but when it comes I'm hanging it on the wall above my desk for easy reference.
One passage in Gillett has me particularly intrigued. He describes a "scout" involving about 30 Rangers out of San Antonio along the El Paso road (El Camino Real), out to Fort Lancaster, then north into the table-land between the headwaters of the South Concho and the Pecos watershed; during said scout their mounts nearly expired from lack of water. They went nearly 48 hours without water, which is a LONG time for horses to go without H2O.
As it happens, my wife and I went for a drive last Monday, headed west across the trans-Pecos just to see what's what, and drove through that very area. (We live very close to the headwaters of what he calls the "South Concho" River.) The drive down the Pecos valley is hauntingly beautiful. By chance we took the side road south of I-10 and stumbled upon the stretch where it overruns the El Paso-San Antonio road across the Pecos to Fort Lancaster. The view from the top of the road east of the Fort at sunset was breathtaking beyond belief. We're planning to return there in a few weeks, I'll make sure I get some photos to post here.
Anyways, look up that map. It might be useful to you.
