Wichita Mountains and Arbiicklc Hills. — Vaughan. 53 
Mr. Hill furnishes the following information concerning 
the pre-Carboniferous rocks of this region : 
Concerning the age of the pre-Carboniferous rocks only a little can 
be said but sufficient to confirm the impression that they include 
Trenton (No. 6), Niagara (No. i). Lower Helderberg (No. 2). 
Could accurate collections be made, many other terranes would no 
doubt be shown to exist. The basis for these determinations are (sic) 
as follows: Near Woodford post-office, ten miles west of the railroad, 
I collected from strata which are continuous with and apparently the 
same as No. 2, the following fossils, kindly determined by Prof. H. S. 
Williams: Spirifera lamellosa, Strophomena rugosa (rhomboidalis). 
Rhynconella nucleolata, Lingula? rectilatera. Concerning these he 
says: "It is safe to say the horizon is Upper Silurian and probably 
equivalent to the Lower Helderberg of New York. It is above the 
Niagara, and this is an interesting feature." Concerning the fossils 
from No. 6, he says they are not very satisfactory but a Trinucleus 
concentricus shows No. 1092 a to be of Lower Silurian, probably 
Trenton age. 
It is not my desire to attempt any classification of these pre-Car- 
boniferous rocks, but I believe from stratigraphic evidence that the 
shales at the south end of the gap may prove Devonian. Beneath 
the Trenton rocks are still older terranes, especially in the Red Bird 
mountains, which may be Cambrian.* 
Taking the approximate determination of the Silurian beds 
from fossils collected by Air. Hill in the Chickasaw and Choc- 
taw Nations, and from those collected by myself in the Chick- 
asaw Nation, Indian territory, and along the northern side of 
the Wichita mountains and at Ft. Sill, Oklahoma, it becomes 
evident that there is a great and probably quite complete se- 
quence of these rocks. 
According to Mr. Hill, there may be Cambrian in the Red 
Bird mountains. Lower Ordovician — perhaps Calciferous— is 
found on the north side of the Wichita mountains, and Low. 
Ordovician, about Quebec, on south side, of Boggy creek, 
eight or ten miles above Stonewall. 
Mr. Hill, as was stated in a previous quotation, foimd 
Trenton fossils. According to Dr. Girty the specimens from 
the Ft. Sill quarry are probably Trenton. Mr. Hill mentions 
Niagara and Lower Helderberg. According to Dr. Girty the 
Strophonella from the cherty limestone is probably of Silurian 
and most likely Lower Helderberg age. 
*Am. Jour. Sci. 3rd Ser., vol. XLII, pp. 121-122. 1891. 
