Coal Measure Horizon hi N. M. — Herrick and Bendrat, 235 
purpose to indicate the conditions as they exist in the Sandia 
mountains, east of Albuquerque. This range is essentially a 
great monocline, the abrupt face of granite, looking toward the 
Rio Grande, being on the eastern side of the fault, the west- 
ern side having dropped from four to ten thousand feet. 
The escarpment is of granite to near its summit where it 
bears the remnant of the stratified series consisting at the bot- 
tom of about fifty feet or more of quartzyte with occasional 
conglomerate phases. The granite has been usually referred 
to the Archean but the discovery of interbedded limestones in 
the granite in the Limitar mountains and the fact that these 
limestones carry poorly preserved fossils would seem to neces- 
sitate the placing of this member in a higher part of the 
column. 
The quartzyte is not generally composed of materials that 
can be directly referred to the granite but rather consists of 
white quartz fragments such as might have been derived from 
veins or more probably from the quartz schists that in many 
cases break through and cover the granite. It is probable that 
there was a long unrecorded interval between the granite and 
the quartzyte, as is further suggested by the extreme irregular- 
ity of the surface of the granite. In regions of great disturb- 
ance in more recent geological time the granite may have been 
again fused and in that case portions of the lower strata were 
lost or incorporated with the schists which are characteristic of 
such regions. It is only in such cases that the quartzyte seems 
to be absent and there will be found small areas where the 
granite is immediately covered by the Carboniferous at various 
horizons.* 
Above the quartzyte in typical sections occurs a series of 
shales, sandstones and conglomerates with occasional bands of 
sandy limestone which we have called the Sandia series. The 
maximum thickness is apparently not over 150 feet. It may be 
that the horizon in question can be identified with some por- 
tion of the Aubrey sandstone as reported by Button in the 
western part of the territory, but the lithological differences are 
so great as to require a distinctive name. 
The variability of the lithological details is considerable. 
*Farther south a larj^e sub-Carboniferous series is intercalated be- 
tween granite and Carboniferous lime. 
