of the prairies, we will pass through wonderful Dantesque 

 gullies, filled with bulging, brightly colored rocks and dotted 

 with junipers, pinons, and little oaks, which every now and then 

 open onto small verdant flood plains with lovely groves of 

 willows and cottonwoods interspersed with thick mesquite 

 clumps. These valleys are filled with twittering flocks of birds. 

 Arriving on the top we come onto a level and more or less bare 

 plain stretching to north, east, and southeast, whil, to the west 

 a great barrier of glowering mountains, usually cloud-covered, 

 rises up like the edge of a continent from the sea. These are the 

 Guadalupes. Sacramentos, and attendant ranges that sprawl for 

 a hundred miles to the north. 



These stand in a sea of scrub, and this low vegetation runs far 

 up their flanks, turning into a typical chaparral. Above this the 

 pinon pines close up to form a transition zone with oaks and 

 some other stunted broad-leafed trees: then these give way to a 

 forest of Ponderosa Pines which increase in thickness and height 

 till at the highest altitudes they are replaced by typical boreal 

 forests of spruce, fir. and aspen. On their western flanks, these 

 mountains descend abruptly onto the Tularosa Plain or Basin, 

 which forms the northern part of the Chihuahua deserts. This 

 vegetational "no-man's land" lies in the North Scrub Belt but 

 partakes of both desert and prairie features, contains forested 

 mountains, and yet does not belong specifically to any one of 

 these provinces. Moreover, it contains some unique features of 

 its own. 



LIVING TORNADOS 



Among the lowest foothills of the eastern face of this range the 

 entrance to the famous Mammoth Cave is situated. This has 

 many miles of passages and is notable for its vast colony of bats. 



There are a number of so-called bat caves dotted about the 

 southern periphery of the great central plains. Besides Mammoth 

 Cave, the most notable is perhaps Ney Cavern on the Edwards 

 Plateau. These contain colonies of almost countless numbers of 

 a small insect-eating bat known as the Free-tailed Bat (Tadarida 

 mexicana). These bats sleep in the caves by day. during which 

 they continually eliminate so that there is a constant rain of 

 their dry excrement, composed mostly of the hard parts of 

 insects, dropping on the floor. Since this has gone on for mil- 

 lennia, enormous guano deposits have formed. This is high in 

 ammonia content, forming one of the finest fertilizers, and has 

 been extensively mined for this purpose. Disturbance due to 

 these operations, together with the draining of swamps and anti- 

 malaria spraying, have greatly reduced the numbers of the bats, 

 but they are still an impressive sight as they stream out in close- 

 packed masses each eventide. Accounts of the discovery of these 

 caves all run about the same: some lone cowboy sees what he 

 thinks is a prairie fire on the horizon one night just before dark, 

 with a huge black smoke plume reaching into the sky. Every 

 evening it appears again. Finally the cowboy goes to investigate 

 and finds that the cloud is countless millions of bats streaming 

 out of a hole in the ground. 



The sight is still impressive, and the noise is deafening — 

 having been calculated to surpass in decibels the amount of 

 noise made by a four-engined plane taking off. But more amazing 

 is the fact that collisions are nonexistent, though it was once 

 estimated that two billion bats came out of Ney Cavern — the 

 entrance to which is not much over fifty feet across — in less than 

 half an hour. The animals spread far and wide to feed at night, 

 and they once formed a major control of the mosquitoes and 

 other noxious insects of the region. I mention these colonies here 

 not because they are typical of either the prairies or the deserts 

 but are rather a special feature of both the North and South 

 Scrub Belts. 



THE ROOF OF NORTH AMERICA 



The natural entrance to this province is via the Estancia Valley, 

 which leads directly from the no-man's land just described. 

 This is a northern prolongation of the Tularosa Basin and 

 penetrates deeply into the Colorado Block. In fact, it is a con- 

 tinuation of a trough in the surface which splits that block 

 from south to north and which continues up the San Luis Valley 

 almost to the towering pinnacle of this continent near Leadville. 

 Colorado. This means of approach is not only most "scenic" but 

 also most highly instructive to those interested in the construc- 

 tion of our continent and the types of flora in which it is clothed. 

 As one proceeds up this valley, all the major belts of vegetation 

 to be found north of the deserts are laid out to left and right 

 along the sides of the mountains, and each dips slowly and 

 peters out in succession — first the scrub, then the grasslands, 

 then the parks disappear, until one enters a beautiful transition 

 zone around Santa Fe. Meantime the mountains on either side 



Left: The Puma is still fairly common in large areas of 

 the West and quite numerous in parts of this province. It 

 is generally retiring and not dangerous. 



Right: The upper slopes of the Colorado Rockies are clothed 

 in true alpine flora with massed conifers. The higher ridges 

 and peaks — "the roof" of America — are barren or snow- 

 covered all year. 



