Geological Rccoimoissance in N. M. — Herrick. 341 
castellated forms to a hight of 25 feet or more. The rock 
has not been examined as yet, but appears to the eye like the 
soda porphyrytes and syenytes of the Ortiz region. Crossing 
this ridge by a rough and romantic road we descend to an 
irregular depression north of Bear mountain. The rocks are 
largely of th.e red series and the waters are accordingly largely 
impregnated with salt. The basalt sheet marks the northern 
walls of this area, which has some portions densely punctured 
by basalt cones and dykes. The Cretaceous appears beneath 
the basalt sheet as we pass west while the red series gradually 
sinks from view. East of Tres Hermanos is an exception- 
ally good exposure showing the three members of the red se- 
ries and a considerable amount of the Cretaceous above. The 
same sequence is observed at this place as near Albuquerque. 
The Dakota sandstone appears to be absent and the so-called 
gasteropod zone is within a hundred feet of the bottom, with 
fossils of Fort Benton age. followed by a band of sandstone 
with enormous concretions. After a series of soft shales the 
zone of cephalopods appears and then the Fox Hills sand- 
stones with their large marine assemblage. 
West of the long tongue of lava-topped mesa that terminates 
in the three basaltic peaks of Tres Hermanos is a valley ex- 
cavated in the Cretaceous and numerous exposures of the Fox 
Hills lignite occur here as w€ll as south of the Alamosa river. 
Passing up Alamosa river, which is chiefly excavated in 
the Cretaceous, the dip again becomes easterly and the strata 
rise about with the inclination of the valley. At range 8, north 
of the Alamosa, is a curious mountain formed by the protru- 
sion of a basaltic neck through the soft strata. This "Turtle 
mountain" forms the southern projection of a long terraced 
ridge at the foot of which is a good exposure of the maroon 
sands and marls of the vermilion division of the red series. 
Above this, in successive benches the sands and shales of the 
Cretaceous are finely displayed and follow the same sequence 
as in the Rio Puerco region. In the yellow sands of the 
Upper Fox Hills it is interesting to find numerous dicoty- 
ledonous leaves, and this is true in all exposures seen, especi- 
ally in the neighborhood of the lignites. 
It would seem that these have led to the identification of 
the beds in question and the associated lignites with the La- 
