While rafting not long ago down part of the Rio Grande in the Big Bend, I learned with a shade of a disappointment that the blackish, dense, fluted, and sculptured material forming the superb high walls of Mariscal Canyon consists of Lower Cretaceous limestone partially metamorphosed toward marble by ancient heat and pressure. Not being a devout or even passably competent geological type, I don’t ordinarily get emotional about the composition of rocks. But a good many years before, I had canoed happily and ignorantly in that region with some others mainly as happy and ignorant as myself, along a stretch of the Conchos in Chihuahua to where it joins the Rio Grande at Presidio in the Big Bend, and when passing through other fine canyons sliced out of that same stone we had airily classed it as basalt. This was because it was dark and hard and sometimes shiny, but even more, I suspect, because “basalt” as a word rang richly in our ears, sounding igneous and exotically different from the prosaic limestones and sandstones and shales we were used to in our more easterly and sedimentary native habitat.
The friend who provided this mild disillusionment, Jim Bones, does not see the Lower Cretaceous as undramatic at all, and of course it isn’t, not in a haunting, otherwordly place like Mariscal Canyon. The Rio Grande, all 1885 miles of it plus some tributaries, is “his” river in a mental way that I understand, having felt thus myself in my time about a couple of other streams. The feeling comes not from deeds of title but from knowledge and caring, and it gives every stone and thorny bush and biting bug and cry in the night its full significance in the riverine scheme of things. Through informed awareness, friend Bones possesses the Rio Grande where it begins in the snowy Colorado Rockies, and where it courses clear and cold and copious through the mountain valleys and high cool deserts of the ancient Pueblo country of northern New Mexico, and in the hotter arid places south of there to El Paso and