288 TJic American Geologist. Novombor, i898 
San Andreas mountains. The western escarpment is for the 
most part very steep with evidence of very considerable meta- 
morphism. The very axis of break in some places is preserved 
and afifords very interesting illustrations of what can be done 
in the way of altering a limestone by the agency of mechanical 
friction and pressure without the presence of a source of igne- 
ous heat. So far as seen, there is no intrusive in this range 
but the displacement along the axis of uplift was very great 
::nd the area afifected was quite narrow. The sequence of the 
strata seems to have been about the same as elsewhere in the 
valley although opportunity was lacking to make a sufficient 
examination of the lower as well as some of the higher strata 
at points where the absence of excessive metamorphism would 
admit of expecting organic remains. The fossils seen from 
the upper part are such as are found in the upper three hun- 
dred feet of the Carboniferous in Bernalillo Co., the abundance 
of Bryozoa being quite characteristic. Below the middle there 
are shaly beds in which are found the same facies which occurs 
in the lower parts of the series as exposed in Socorro and 
Bernalillo counties but the lower one hundred feet is so al- 
tered in all the places visited thet it is impossible to deny the 
local belief that it contains some strata of an age' earlier 
than the Carboniferous. However, it may be said that there 
is no evidence of unconformity in the series where undis- 
turbed and there is nothing in the lithological character of this 
portion to dispose one to regard it as other than the sandy 
lower part of the Carboniferous as seen elsewhere in the valley. 
Such fossils as Chonetes mesoloba, Spirifer opirna, Martinia 
lineata, Aviculopectcn carbotiiferus, Terebratula spf Pro- 
ductus corn, P. nebrasccnsis, in the lowest fossiliferous beds 
examined and certainly below the middle of the series permit 
us to expect that the lower p^rts will prove Carboniferous. 
The foot of the western slope is granite, gneiss or schis- 
tose rock of a somewhat nondescript character, varying from 
plr.ce to place and much mingled locally along the axis, which, 
while in general trending north and south, has many local off- 
sets and irregularities. Above the granite is a band of quartz- 
yte as usual, the thickness being little more than twenty 
feet. At the contact with the limestone series is a coarser 
phase which from its position immediately above the impervi- 
