Jciiiea — Albuquerque^ iV. Mex. — Regan. 85 
mesa is reached thus indicating that the Nacimiento moun- 
tains here have been gradually elevated at the south through- 
out many geological ages. Now, in Eocene time these moun- 
tains, in their upward movement, were continually pushing 
the Tertiary lake shore farther south, till the northern limit of 
this lake was about on a line with Mesa Blanco and the Jemez 
river in its lower course when the marl stratum of the Zia 
mesa was deposited ; this marl then would not appear to the 
north of that river. Proof that this interpretation is a correct 
one is shown by the fact that the marl extends west of Mesa 
Blanco, as we have seen, to the Rio Puerco below Capizon ; 
but to the north of this line it tapers out to a thin edge and 
disappears. 
The Pliocene Strata. — At the close of Eocene epoch, there 
was a faulting and breaking up of the country on a grand 
scale. The great Eocene lake (sea) was obliterated ; and in 
its stead all the troughs made by the faulting and shifting of 
the strata became fresh water lakes. One of these lakes oc- 
cupied the area between the Zia mesa at the south and the Red 
Bed and Carboniferous mesa north and west of Jemez Pueblo, 
covering an area of more than 80 'square miles. Another 
large lake occupied the Rio Grande valley from the Eocene 
bluffs west of the present river east to the foot of the San 
Dias. 
The serata of this formation are alternating softer and 
harder calcareous sandstones and conglomerates varying from 
white to deep green and light rufous. 
The Jemez Marls. — This series in the Jemez valley is al- 
ways capped with a conglomerate stratum now considerably 
cut up and eroded. The marls are a lighter color and also' 
much softer than the marls in the Eocene formation, just de- 
scribed. The Indians at Jemez call these marls "Dafwa" and 
use them for various purposes. The marl is pulverized and 
with it a whitewashing solution is prepared, which is more 
desirable than the standard material prepared from gvpsum. 
The writer will adopt the Indian name Jemez for these marls. 
The Jemez marls are 250 feet in thickness on the bluffs, in the 
vicinity of Jemez ; but in the valley of the Jemez their thick- 
ness is less than a hundred feet. They rest upon the strata of 
various formations ranging from Carboniferous to Eocene. 
