,^t 



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. 



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