CorrespoHdeace. 57 
the large areas of conglomerate or "wash," especially along the Gila, 
Sapillo and MiraV)res rivers. This last formation, which Varies consid- 
eraVjly lithologically, often attains a thickness of over one thousand 
feet, and has a prevailing yellowish-buff color. In many places the 
basalt has forced its way through and overflowed this late formation: 
while at other localities large areas have been uplifted, tilted and bro- 
ken by eruptions of basalt. 
The next division of greatest interest, although of relatively small ex- 
tent, is the strata representing the Lower Carboniferous and Creta- 
ceous* ages, all of which are much tilted and broken up by eruptive 
agencies. The Cretaceous is mainly composed of rather coarse, brown- 
ish-buff to gray (sometimes red, locally) sandstone and quartzites, in- 
terstratified with a few narrow bands made up almost exclusively of 
beautifully preserved fossil remains, mainly Gasteropoda and Lamelli- 
branchiata and alternate layers and heavy strata of greenish-black 
arenaceous shales, in places cai-rying an interesting flora. 
What is of peculiar interest is that almost evejywhere, as yet observed, 
the Cretaceous strata rest immediately upon the granite below, instead 
of being superimposed upon the older stratified rocks. Only in one or 
two local areas have I observed the Cretaceous to rest upon the Car- 
boniferous, and here, as might be expected, unconformably. 
The Carboniferous is composed of heavily bedded bluish-black lime- 
stone, often containing a great amount of chert and yellowish-buff cal- 
careous, and black carbonaceous shales and quartzite. The strata 
above the quartzite (except the beach shale, which carries a unique but 
rather rich flora) contain extremely interesting and rich faunas. The 
fossils are often weathered out (from the calcareous shales) in great 
numbers and perfect condition. 
The fourth division, although first as to magnitude of area occupied, 
is the Drift formation, which is of much interest and constitutes the 
great desert plains of this region that stretch onward far into old 
Mexico. 
In the Drift at Deming two apparently entire and well preserved 
skeletons of mastodons have V^een exhumed in digging wells, one being 
discovered approximately twenty feet and the other forty feet below the 
surface. Only a portion of each skeleton was removed. 
A large amount of data in the form of notes, maps, sections, ores, 
minerals, fossils, etc., have been collected, as well as a large scale geo- 
logical map of the region constructed.! A detailed account of the re- 
sult of the field work, etc., accomplished will be published in the near 
future. Clement L. Wkbstek. 
*I have here proivs/'oHC^/// considered all tlie strata above the rarboiiiferous (not 
includinK- the contrlonierate) as of Crctac(!ons age. and all below the (^retaceoiix as 
Carboniferous. The (]nestifin as to th(> exact affe of the (juartzite (usually considered 
as Silurian I occu|)yin!.' the lowest horizon in the stratified series here;, will be dis- 
cussed in my fntui-e publications on tiie treoloj^.v of this ref^iou. 
tI woiihi here acknowledge my indebtedness to Prof. .J. H. Huntington (who has 
si)ent many years in southwestern New Mexico), assistant geologist on the State geo- 
logical survey of New Hampshire, for valuable assistance rendered in my geological 
labors in this region. 
