Copper and Lead in New Mexico.— Herrick. 285 
thin flat pebbles on the surface of water in which they could 
not be transported if immersed, a fact which may explain 
the presence of scattered grains of coarse sand in beds of 
fine clay. 
The occurrence as seen by Mr. Graham was the removal 
and floating away of sand by gentle waves, splashing against 
the bars along the margin of the Connecticut river. 
Prof. Simonds describes his observations on the Llano 
river, in Texas, where dry sand was gently fed to the surface 
of the water by an undermining process. He explains it 
vaguely as a phenomenon of "superficial viscosity." 
THE OCCURRENCE OF COPPER AND LEAD IN 
THE SAN ANDRE.A^S AND CABALLO 
MOUNTAINS. 
By Pres. C. L. Hereick, Albuquerque, New Mexico. 
A somewhat interesting occurrence of copper in the moun- 
tain chain lying on the east side of the Rio Grande valley may 
be most easily understood from the conditions in the San An- 
dreas, which lies some ten miles east of Lava station south of 
Socorro. The railroad here seems to pass through a syncline 
as the exposures of Carboniferous near the river dip to the 
east while the strata in the Andreas dip towards the north- 
west. To one approaching them from the east, that is from 
the plain of the white sands, the mountains present a rather 
abrupt escarpment rising nearly directly from the plain. The 
face is cut here and there by valleys and canons, but the con- 
figuration and geologic structure are remarkably uniform. The 
lower part of the scarp is composed of granite, gneiss or 
quartzyte of the mctamorphic series and in this respect the 
conditions are precisely as in the Sandias and elsewhere in the 
ranges bordering upon the Rio Grande. Above this granite 
base rises the stratified series composed of Carboniferous 
limestone and interbedded sandstones with a thickness of 600 
to 700 feet. In lithological and paleontological character this 
series presents no noteworthy peculiarities, but it differs from 
the similar exposures further north in the fact that the entire 
limestone series is cut by nearly vertical veins of considerable 
