January 20, 1905.] 



SCIENCE. 



91 



level between segments of corresponding 

 strata. Here the weird Organ mountains 

 break the horizon by upthrust spires and 

 pinnacles of granite which to some early 

 voyageur crossing these dusty plains sug- 

 gested the pipes and architecture of some 

 far-oft' organ, and the mountains were so 

 named ; but upturned granite means that 

 the sedimentary rocks are here further up- 

 lifted still than on the eastern side, so that 

 we quickly find ourselves in presence of 

 vast parallel faults and our desert lies thus 

 between their giant walls. It is as if half 

 the region between this city and New York 

 should suddenly sink two or three thou- 

 sand feet, or what is the same thing, it is as 

 if the several thousand feet of difference in 

 level were brought about by the depression 

 of the included area, and the simultaneous 

 elevation of the sides. At any rate, the 

 desert plain of the Alamogordo or Tularosa 

 sands is simply the upper surface of a 

 gigantic block of the earth's crust that 

 sank some time subsequent to the deposi- 

 tion of the Jura-Trias and the earlier 

 cretaceous strata of this western world. 

 These strata include, as we know, the 

 famous 'red beds' which tinge the moun- 

 tains of half the continent, the red beds 

 with all their gypsums, marls and salts of 

 every description. Accordingly, as a re- 

 sult of this faulting, our desert has for its 

 foundation everywhere great fields of gyp- 

 sum, often for long distances Avide-exposed, 

 sometimes thinly veiled by loosened sand, 

 sometimes deep buried by vast deposits of 

 wine-red marls and clays, or covered anon 

 by the products of erosion, whether by 

 water or by wind. The waters from the 

 mountain snows have brought their debris ; 

 the winds of the " desert have come with 

 their burden, but nowhere has such trans- 

 portation traversed the desert borders, at 

 least in recent times; there are to-day no 

 excurrent nor percurrent streams; the 



winds die along the mountain walls and 

 the waters sink in the desiccated sands. 



But this is not all. This great sunken 

 block of earth's crust seems itself to have 

 been cracked again and again; there are 

 secondary faults, and along the line of one 

 of these thinner or weaker places the sub- 

 terranean energies of the world have some 

 time found emergence. Floods of lava 

 welled up in the midst of the desert, and 

 fountains of fire streamed along the 

 ground, following existent topography for 

 miles and miles, now narrowing to dimen- 

 sions measured by rods between low ranges 

 of hills, now widening for miles across the 

 broader valleys, only to lie at last a vast 

 field of blackened cinder, slowly disin- 

 tegrated by the desert storms. This is one 

 of the most peculiar topographic features 

 of the whole desert. As things terrestrial 

 go, this is a recent phenomenon. The age 

 of the lava may be measured by centuries, 

 a few thousand years, it would seem, at 

 most. The surface over which it poured 

 was a friable, marly soil. As the floods 

 cooled, the mass cracked and gaped in every 

 direction. Rains descending upon the sur- 

 face sank to the ground below and shaped 

 for themselves channels. The lava so un- 

 dermined has fallen into a tumbled ruin 

 of weirdness and confusion, indescribable, 

 impassable. 



The lava constitutes one of the features 

 of this remarkable desert; there is yet an- 

 other. Along the western border, partly 

 uncovered by erosion, partly by the west- 

 ern winds, great bodies of gypsum lie ex- 

 posed. As this slowly disintegrates the 

 wind gathers the particles set free and 

 bears them eastward, the famous white 

 sands, covering township after township 

 with drifted mineral white as snow. Vast 

 windrows shifting slowly with every storm, 

 and forever reinforced by the unceasing 

 contributions of the west, mark the land- 

 scape over several hundred square miles. 



