Jellies — Albuquerque, N. Mex. — Reagan. 87 
to ten feet in thickness. The upper strata are adobe. The line 
of thickest deposits Hes in a north and south direction and con- 
forms very nearly to the present course of the Vallecieto creek 
which runs through the area. It tapers out to a thin edge to 
the west in less than a quarter of a mile while to the east it ex- 
tends for more than two miles. The eastern margin lies on the 
Tertiary, the middle or lowest on the Cretaceous, and the west- 
ern margin on the Red Beds. In Pleistocene times this area was 
a lake, and was initiated by the shifting of the strata to the 
south and east of the Red Beds hogback at the close of the 
Tertiary, and remained laked till a channel was cut along the 
fault line to the southwest, thus giving it an outlet to the Jemez 
river. Along this fault the river has cut a deep channel 
through the solid Red Beds to get an outlet, although the 
strata to the southeast of the lake is but partly lithified sands 
and clays. This shows that faulting aided in locating the pres- 
ent channel. There is also strong evidence to show that the 
basalt eruptions took place in Post Tertiary times, because the 
lava flowed into the lake and at the eastern margin is inter- 
bedded with the Pleistocene deposits here described. 
The Placita Marl. — The Pleistocene deposits between San 
Felipe and Placita are found in the depressions between the 
rolling hills. In places they overlie the Tertiary, at others, the 
Cretaceous, and near Tejon, the Carboniferous. On the east 
they are closed in by a spur of Red Beds which projects north- 
eastward from the foot of the San Dias. The above indicates 
that there was an erosive period after the close of the Tertiary, 
a lost record, before the Pleistocene deposits were laid down. 
These deposits are cross bedded promiscuously mixed sands 
and gravels overlaid with thick deposit of adobe clay. 
Dr. Cope visited these deposits and in his remarks about 
them, says : 
"A section carried across from Algodones (near San Fel- 
ipe) on the Rio Grande to the San Dia mountains through the 
village and creek of Placita, gave the following results : The 
road winds among and ascends for several miles mesas of 
coarse Tertiary gravel and cobblestones until it reached a wide 
plateau, from which the mountains rise on the east. This tract 
is traversed by Placita creek and its tributary arroyas which 
furnish interesting sections. From these it appears that the 
