i88 The American Geologist. September, i904 
shells serves to indicate a comparatively fresh condition of the 
waters during the hight of the period. 
Economic E.rploitation. Some eftorts have been made 
to utilize the gypsum sands, a companv having been formed 
operating from Alamogordo for the manufacture of cement 
and artificial stone. It would appear that the more impure 
deposits occasionally occur in such mixtures with earth and 
vegetable matter as to require no retarder and simply need 
to be partially burnt to be ready for use. Artificial stone and 
stucco are produced but much remains to be done in the 
practical exploitation of what will sometime prove a great in- 
dustry and afford a substitute for the lumber which at no 
very distant date will disappear from the southwest. Mexioo 
affords an illustration of the great variety of uses to which 
a cheap cement may be* put. Irrigation ditches and wiers as 
well as very substantial buildings are constructed of com- 
binations of adobe, poor brick, and cement. In this country 
the use of slow setting ("dead burnt") plasters is not in 
vogue so that great care is necessary to get the right degree 
of dehydration. 
The entire region is strictly saline and the thin covering 
of sandy marl of the Tularosa formation does not disguise the 
fact, though in the vicinity of the talus fans, especially on 
the east side of the valley, there is a fringe of good soil which 
will prove very productive when irrigated with fresh water. 
Such towns as Tularosa and La Luz near the base of the 
mountains are surrounded by thrifty orchards and alfalfa 
fields. There is little doubt that mountain reservoirs may 
do much towards the reclamation of a part of this area, but 
in the bed of the lake out from the immediate margin the 
salinity of the Otero formation will always impregnate the 
superficial layers. 
Although the only economic use so far made of the 
vast deposits of salts has been that of ♦"he local stock men who 
occasionally drive into one of these flats and shovel up a 
load of salt, is is probable that a large industry will one day 
be carried on here. It will be found possible to evaporate the 
brines by a solar process on a very large scale and the cement 
for making the pans is immediately at hand. Cheap coal 
