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THE POPULAR SCIENCE MONTHLY 



Fig. 2. Enchanted Mesa, in Western New Mexico ; a High Remnantal Plateau 



of Small Area. 



planes, beveled tables of flexed strata, lava-sheets, or cemented regolith, 

 are of quite different elevations even in the same district. In New 

 Mexico, for instance, these plains attain all altitudes above the general 

 plains-surface, from a few feet in the case of the very recently formed 

 Malagro malpais, in the Hueco bolson northeast of El Paso, to the 

 broad Mesa de Maya which is 3,500 feet above the general plains-surface, 

 and 9,000 feet above the sea-level. The Sierra del Datil in western 

 New Mexico has a magnificent northward-facing escarpment 1,000 feet 

 high; and in sight of it is the Acoma Mesa 500 feet above the plains- 

 floor (Fig. 7). 



Toyalane is a conspicuous flat-topped mountain situated just over 

 the continental divide. The region is the largest, highest and driest 

 desert plain in this country. Structurally and topographically it con- 

 stitutes an essential section of the great Colorado dome, arching from 

 the Eio Grande to the Rio Colorado. Save in one place — the Zuni 

 Swell — its surface is unbroken by tectonic features. In this mesa-land 



