42 The American Geologist. July, i898 
In the immediate environs of Albuquerque there are no 
complete exposures of the Cretaceous, but at a point on the 
west side of the Rio Grande about three miles northwest of the 
bridge at Los Corrales there is a fairly good continuous ex- 
posure of sands and marly lime referred to this period. The 
rock is very slightly coherent — scarcely more than a crag — 
and occurs in bands of red, yellow and white, while near the 
top is a narrow band of lime containing some imperfect re- 
mains which have not yet been studied. The entire thickness 
exposed is rather over one hundred feet, of which the lower 
half is of red sand with nodules of greater consi-stency. Some 
layers are quite firmly cemented. Near the top of the light- 
colored division the sand is loose and contains numerous peb- 
bles of red and black chert, quartz, quartzyte and other ma- 
terials apparently of granitic origin. It appears that this Cre- 
taceous series is the country rock back from the river and that 
it has furnished a large part of the materials for both the 
older and the more recent river deposits. The valley nearer 
the river at this point is filled with materials similar to the 
portion about Albuquerque, the loess being below and over- 
topped by coarser material deposited on the eroded surface of 
the loess in sand-bar formation of the most interesting sort. 
Prominent among the coarser materials are fragments of 
basaltic lava evidently derived from flows higher up the river. 
No such material is seen in the Cretaceous gravel beds. Re- 
specting the latter it may be noted that these beds are similar 
to those occupying the hills northeast of Socorro, where they 
are conspicuous by reason of their colors and stratigraphic 
distinctness. 
IV. The Albuquerque Volcanic Group. 
A good illustration of the circumscribed lava flows from 
the latest eruptive cones is seen about six miles west of Al- 
buquerque. Here five small cones rise in a group from the 
western crest of the valley. The axis of the group is north 
and south. Each cone may be the core or plug of the orig- 
inal crater, but, in that case, the walls of the crater proper 
have disappeared. It is claimed that there are evidences of 
local heat and vapors, but of this we have no evidence. The 
lava is a black vesicular basalt, and it extends in all directions. 
