98 Bulletin of Laboratories of Deniso^i University [Voi. xi. 
that the yellow and irregular banded sandstone is substituted for 
by massive white sand for shorter or longer distances. Above 
this layer is a conformable bed of yellowish loamy clay which is 
very finely banded and homogeneous. To the east the inclina- 
tion of the faulted blocks becomes less, those near the river 
having a dip of about five degrees. Near the eastern margin 
of the valley the strata are nearly horizontal and the Cretaceous 
strata describe above disappear below the surface. Their place 
is occupied with bands of sand which have the texture of the 
upper loamy layer mentioned as overlying the Cretaceous near 
the river. The color is variable however and the strata are so 
disturbed that it cannot be said certainly that the two are part 
of the same system. We incline to that view and think that 
the red sands which appear in the eastern wall of the valley, 
inclined at a barely perceptible dip, are of the same age as the 
outliers in the eastern part of the valley and these in turn of the 
same age as the remnants of fine material on the upper surface 
of the Cretaceous near the river. 
At present we can only conjecture that these sandy beds 
are of Tertiary or Pleistocene age. 
THE SANDIA MOUNTAINS. 
This range is the most conspicuous mountain group visible 
from Albuquerque, directly east of which it lies at a distance of 
from five to eight miles. The highest point of the range is 
about 10,000 feet above the sea or a little more than 5,000 feet 
above Albuquerque. The mountains are part of a great mono- 
cline which extends along the left bank of the Rio Grande to 
the south. This monocline passes into an anticline by degrees, 
as the Ladrones, Limitar Mt. and Socorro range contain the 
same formations dipping to the west on the right bank. The 
Rio Grande may be said to occupy the axis of an anticline or, 
better still, an axis of disturbance which in various parts has 
resulted in different geologic structures according to circum- 
stances. . These disturbances were inaugurated, so far as the 
