88 The American Geologist. February, i903. 
greater part of the plateau consists of the yellow, muddy- 
shales and sandstones of Cretaceous number I. They form the 
bottoms and sometimes the walls of the arroyas, and rise in 
low monoclinal hills at various points on the plateau. The 
beds dip northeast 20^ to 40°. In the intervals between the hills, 
there is a deposit of indurated clay of 40 feet in thickness, of 
Pleistocene age. I obtained teeth and other bones of Elephas 
primigenius, subspecies cohimbi, from this bed, and found 
bones of elephants in place in the banks of the arroya. Shells 
of Planorbis, Physa etc. indicate the lacustrine character of the 
deposit which I have called the Placita Marl."^- 
Deposits of the Jenies Valley. — The Pleistocene rocks of 
the Jemez valley are interstratified sands and clays. A section 
in the government well at Jemez showed the following: 
Adobe clay at the surface 9 ft. 
Cross bedded sand 4 ft. 
Adobe clay, an old forest ground 6 ft. 
Whitish yellow clay filled with freshwater 
gasteropod shells that look as though 
they were the same as species now living. . .6 in. 
Cross-beded, loose sand i ft. 
Conglomerate in which the prevailing cob- 
ble stones are black vesicular basalt 2 ft. 
Red brown sand stone (Tertiary) i ft. 
The above section was taken at the eastern margin of the 
deposit. The strata are much thicker in the central part of the 
area. 
Another section was obtained from the government well 
made for the Zia Indians on the Zia reservation. There the 
adobe clay at the surface was found to be 16 feet thick and 
the underlying loose sand to be much thicker. The well did 
not penetrate the entire thickness of the latter. 
These Jemez valley deposits cover a large area. They ex- 
tend along the Jemez river from Canon de los Jemez to the 
Bernalillo volcanoes a distance of 25 miles or more. Their 
average width is from i to 5 miles. This does not include 
the deposits along the lower Vallecieto creek, and lower Salt 
river, which in each case are very extensive. In these deposits 
at a considerable distance below the surface and far from the 
present river channel, wood is found, well preserved, though 
not petrified. These deposits by comparing them with those 
