i64 The American Geologist. ^^aici., looi. 
lying red shales and sandstones has not been satisfactorily de- 
termined. 
Devonian. Near Greaterville in Prince county on the east- 
ern side of the Santa Rita mountains I have found a locality 
of Devonian fossils in limestone, and have collected Spirifer 
hungerfordi, Atrypa recticularis Bellerophon and the coral 
Acervularia davidsoni, besides others not yet determined.* 
These occur in a massive bed of light colored limestone stand- 
ing nearly on edge contiguous to a thick stratum of limestone 
conglomerate made up of rounded pebbles of limestone, un- 
questionably derived from some older beds. 
In the Box canon which cuts through this mountain from 
east to west there is a remarkably interesting section. Resting 
upon a coarse porphyritic granite at the western side we find in 
nearly vertical attitude a pebbly conglomerate overlaid by 
quartzyte and this in turn by a thick series of red shales prob- 
ably over I, GOG feet thick. At the eastern end a last exposure 
ot this section, the fossiliferous limestone, the equivalent of 
that at Greaterville and like it, accompanied by the calcareous 
conglomerate, crops out in such a way as to render its relation 
to the red shales obscure. There is seemingly a break and want 
of conformity as at the Catalina section farther north. 
Faulting. There have been great faultings and displace- 
ments over the entire area of Arizona, notably along the valley 
of the San Pedro northwest and northeast.! In the Huachuca 
mountains on the western side of this valley the dominant char 
acteristic section is a very heavy regularly stratified quartzyte 
surmounted by limestone and resting upon porphyritic granite 
and presenting bold escarpments towards the east. In the sec- 
tion of these mountains thick beds of red shales are found like 
those of the Santa Ritas, while higher in the range there are 
massive strata of limestone conglomerate apparently not con- 
formable with the red shales. This conglomerate appears to be 
the equivalent of that found in close association with the De- 
vonian limestone of Greaterville. 
Silurian and Cambrian. We are without evidence by fossils 
of the existence of Silurian terranes, but the identification of a 
* In the identification of the species mentioned I have had the assistance of 
Prof. C. E. Beecher of the Peabody Museum, Yale University. 
i- Such faultings have been noted and described by Dr. Comstock. 
