O o 
3 35' 
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9 № 
COLORADO PLATEAU 
VOLCANIC MOUNTAINS 
VOLCANIC NCCK 
||si; ..'vlS 
8ASIN RANGELAND 
Fig. 2.16 Volcanic mountain type. This volcanic cone, with 
an elevation of 11,400 ft., erupted above a high plateau, 
covering its sandstone strata with a lava cap. The plateau 
has a cover of pine, which gradually changes to fir, spruce 
and aspen on the mountain slopes. The timber is -low in 
quality because of the poor lava soils. Extensive grass 
lands at upper elevations, caused by old burns, provide sum 
mer range for cattle and sheep. The local climate is sub 
arctic with deep snows in winter and cool summers. Precipi 
tation averages between 30" and 40". Movement over terrain 
of this type must be by trail or by steep logging roads. 
Mountains of this type provide water for irrigation because 
of the large amount of rainfall, but water is scarce at 
higher levels because of the porosity of the rock. 
Mt. Taylor, near Grants, New Mexico. April 1949. 
COLORADO PLATEAU 
UPLIFT MOUNTAINS 
Fig. 2.17 Uplift mountain type. This 6,700 ft. mountain 
is an elongated dome from which the upper sedimentary rock 
has weathered, leaving cuestas on all sides. It has a veg 
etation cover of pine forests of good quality and high ec 
onomic value, and its open parks provide summer range for 
cattle. The local climate is temperate with moderate snow 
fall in winter and warm summers. There are moderate summer 
rains and precipitation amounts to 20" - 30". Movement over 
this terrain may be over a network of good timber access 
roads with their many minor spur roads. A fire lookout is 
located on the highest peak. Springs and running streams 
are scarce and frequently dry up in summer. Zunl Mountains, 
near Grants, New Mexico. April 1949. 
GVII-98 PHOTOGRAMMETRIC ENGINEERING