Art. V.] Herrick, Geology of New Mexico. 103 
the river. Here is a bed of marl and crag reminding of the su- 
perficial layer opposite Albuquerque, The whole area south of 
Thornton seems to be similar till the Jura-triassic area at Galis- 
teo creek west of Cerrillos is reached. At the very north end 
of the mountains the foot hills seem to be of Cretaceous and 
Jura-triassic but the disturbances have been so great that little 
has been done in unravelling the complicated relations. A 
deep canon cuts far into the range from the north, at the mouth 
of which is the Mexican town of Placitos. The canon is due 
to the extensive fault in the Carboniferous limestone by which 
the lime after dipping from the crest to near the general level 
on the west side of the canon, reappears on the east side in a 
precipitous cliff of perhaps 600 feet. The valley is cultivated 
for a number of miles and apparently contains Cretaceous strata. 
At the extreme northern limit of the eastern wall of the canon 
there is a series of springs and a very confused area. It here 
appears as though the limestones of the Carboniferous were fol- 
lowed with only slight disturbance by the beds of the following 
formation. A limestone occurs which contains fragments of Car- 
boniferous lime together with their fossils commingled with fos- 
sils of a different habitus. The remains are poorly preserved and 
no decision can now be reached as to their age. Among these 
beds are others composed of red granite fragments, forming a 
small-grained conglomerate. Red sandstone and shales seem to 
follow, to be in turn succeeded by banded quartzite and other 
beds ot shale and sand and still other strata of quartzite. The 
strata all dip to the east and it is hard to determine whether the 
series (here regarded, on lithological evidence alone, as Jura- 
triassic) is quite thick or whether it is frequently repeated by 
faulting. East of these exposures there is a very prominent 
ridge with its abrupt escarpment toward the west offering the fol- 
lowing section : at the base at least 200 feet of red sandstone 
with irregular layers of vesicular limestone, then 85 feet of sac- 
charoidal white sandstone and on top a band of 1 5 to 20 feet of 
yellow limestone. This section is crossed by the road to Tijon 
where are saline springs. It is probable that the upper part of 
the section is Cretaceous. The region to the east of this ridge 
