178 
The American Geologist. 
September, 1904. 
supposed to be of Permian age, and evidently represent the 
tops of faulted blocks indicating a drop of perhaps 4000 to 
5000 feet. Similar conditions are not known to exist on the 
west side of the valley but the tops of faulted blocks may be 
buried beneath the sediments. 
Four fossils from the Cerrito Tularcsa, an outlier of Permian limestone 
along fault line on the east side of Lake Otero basin. 
It is clear that the axis of uplift became a drainage axis 
quite early. To the east the sedimentaries carried to the top 
valley, where, as I am informed by Dr. W. G. Tight, who has 
studied the region, they form the water-bearing horizons of 
that celebrated artesian area. The same mav prove to be true 
of the plains to the west of the San Andres known as the 
Jourado del IMuerto (Journey of Death). Although the 
fracture axis of our valley may have been early, the latest up- 
lift of the Sierra Blanca was certainly later than the Cretace- 
ous for Mr. H. N. Herrick has collected Fox Hills fossils 
from well up on the western slope and a curious broken area 
of Cretaceous intersected by dikes of recent basalt occupies 
a position at the base near Three Rivers and this block is 
faulted down to the level of the Permian which borders it. 
It may be supposed that the great faults which reduced 
the valley to something like its present level occurr.»d during 
late Cretaceous or Tertiary time, though even greater disloca- 
tions may have followed the period of the Red Beds, i. e. at 
