Title: The continent we live on
Identifier: continentweliveo00sandrich (find matches)
Year: 1961 (1960s)
Authors: Sanderson, Ivan Terence, 1911-1973
Subjects: Physical geography; Natural history
Publisher: New York : Random House
Contributing Library: New College of California
Digitizing Sponsor: Internet Archive

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west side you may look into the Grand Canyon of Saint Helena, from which the river debouches onto a narrow sand-covered plain supporting a forest of huge willows and cottonwoods. Both natural and some artificial meadows of lush grass border this on the north side. The south bank lies at the foot of a gigantic cliff. That is Mexico. Most of the Big Bend area is extremely arid, the valleys and the slopes being covered with cactus scrub and some of the taller mountains being completely bald. The rocks sometimes take grotesque shapes, and large arroyos have been carved out of the uncompacted surface strata and the outwash soils. Despite their towering heights, the Chisos and associated mountains are formed of an ancient plateau that "fell" or sank some thousands of feet into the earth between two faults. Later, the middle of this block was upfolded by pressures from beneath; then vol- canicity added its efforts, further elevating the surface and pour- ing out massive strata of lava. Thus, today, the Chisos rise from a hole in a plateau, but to a height that carries their peaks well above its general level. The Cacomistle or Ring-tailed Cat, a small, soft-furred, and agile type of raccoon found all over the West and Southwest. It can squeeze into tiny crevices.
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The rocks of the old plateau were formed under a sea that very long ago extended up the center of this continent from the Gulf of Mexico to the Arctic Ocean and that later formed great lagoons, coastal swamps, and lakes. Coal beds were laid down in these and the fossil remains of dinosaurs are now to be found in them. Above these are later strata of the Tertiary period, the age of mammals, which contain certain long-extinct animals of great interest, known as Hyracotheres. These were nondescript mam- mals, the size of a large dog, with five toes in front and four behind, all of which terminated in tiny hoofs. They were members of the stock from which the horse tribe later arose. The earliest known member of that tribe is a remarkably similar-looking beast named Eohippus. or the Dawn Horse, found in Egypt and North Africa in strata of similar age. The Chisos Mountains themselves are of extreme beauty. They appear to rise almost straight up in towering red grandeur, and as you go up into them you encounter unexpected growths of all manner of trees. On their summits are pure stands of very fine Alligator Junipers and large Mexican Pinon Pine. There are three species of oak. Higher up still are Ponderosa Pine and even Douglas Fir. In one small place there are great Arizona Cypress, and in another even Quaking Aspen. No less than two hundred species of birds have been observed here, among them both western and eastern species. The list is outstanding for the number of species of birds, such as eight hummingbirds, fifteen hawks, five doves, four jays, four juncos, seven owls, twenty sparrows, six wrens, and seventeen warblers. Outstanding species are the Colima Warbler and a hawk called the Aplomado Falcon. Over fifty-five species of mammals have been observed, and fifty-four reptiles, including twenty-two lizards and twenty-eight snakes. The Chisos form an outlier of the great mountain chain that includes the Rockies and the Sierra Madre Oriental, and they are a stepping stone from the vegeta- tion of one to the other. Plants grow and birds assemble on their summits from both areas. They form, in fact, a northern exten- sion of the eastern Sierras, as may be seen by the map. The whole Big Bend area, not just the Chisos Mountains, is a mecca for botanists and zoologists, for even the apparently arid plains and valleys that surround the mountains support a varied fauna. In recesses far from human passings you may find the Pronghorn Antelope, and after dark the Peccary seems to mate- rialize in droves from nowhere. The beautiful and agile little Kit Fox is plentiful, as it has food here in great abundance. Innumer- able mice and other small rodents swarm, and the Antelope Jack Rabbit is everywhere. LESSER DANGERS There are also in this province two small (two-inch) kinds of scorpions technically named Centruroides that are really danger- ous. These are slim and light-colored, and they run about rather fast on the open ground at night with their pale, slender pincers held before them at the ready. If they encounter anything that moves or that their senses tell them is animal, they stick their tails forward over their heads and then upward, jabbing a mi- nute, hypodermic spine into the prey. This may well be your leg or any other part of your anatomy if you have left it uncovered. The results can be very serious. By official record, more deaths occur in Arizona from scorpion stings than from all other animal stings or bites combined, rattlesnakes not excluded. Not all scorpions are deadly. Of over twenty species recorded from Arizona alone, and many others from the southern reaches of this province, most of the larger

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