File:The continent we live on (1961) (20684838765).jpg

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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The evening flight of hats from limestone caves in the southern phiteau area is one of the world's wonders. Millions issue forth in half an hour, entirely without collision. show clearly first the boreal forests, then alpine meadows and tundras, and finally bare rocks coming in above. Finally, one bursts onto the San Luis Valley, and there in the distance are mighty snow- and ice-covered mountains, range beyond range, straight ahead. This valley is low enough to be prairie-clad with pleasant parklands around its edges, but it sinks to the north (relative to its latitude) so that some very dry scrub basins occur therein. It is well worth turning to the right about halfway up this valley, going over the La Vela Pass and down to a place called Walsenburg. Here you run down onto the real prairies, on which pronghorns may be seen grazing, while off to the south stand the towering twin Spanish Peaks. These are isolated ancient vol- canos, and all around them on the great sweeping grass-covered gutters that run to their feet are some remarkable geological struc- tures known as dykes, which look like enormous, black, man- made walls, sticking straight out of the plain and all running like spokes of a wheel toward the peaks. These dykes are the remnants of deep lava flows that were pushed up through great cracks in the earth's surface. There are also, dotted about, some cone- or tooth-shaped structures known as volcanic plugs, which are the fillings of old secondary volcanic throats whose cones have been worn away by erosion. The fauna of these mountains is large and varied—elk, deer, puma, bear, and all the lesser fry, with a tremendous emphasis on colorful birds, notably the Mountain Bluebird. The lower slopes are clothed in pinons and junipers, the middle slopes with massed ponderosa pines, and the upper with spruce, fir, and aspen. The peaks have a wide belt of alpine tundra, then are bare and finally snow-clad. A similar arrangement of zones prevails all the way north throughout the Colorado Block, rising to a crescendo about iVlount Elbert, where there are high sus- pended valleys clothed in alpine meadows running up to dense fir forests just as in Switzerland. But we should again turn aside, this time to look at one of nature's oddest sights. This lies at the foot of the Sangre de Cristo Mountains in the San Luis Valley. 202

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