GEOLOGIC SECTIONS. 303 



PRESTON SECTION. 



This section is from Tishomingo, Chickasaw nation, south Avard to Sher- 

 man, Texas. It is typical of the western portion of the area, and the 

 following beds are exposed • 



Pleistocene and recent { geeondTottom deposits. 



{Austin chalk. 

 Eagle Ford shales. 

 Lower Cross Timber (or Dakota) sands. 



Main Street limestone . ] 



Washita division ] Marietta beds J 



Fort AVorth limestone. 



Duck Creek chalk I x> *. -u j 



Kiamitia clays [ Preston beds. 



Lower Cretaceous . . . | Fredericksburg f Goodland limestone. 

 (Comanche series). division. \ ^V alnnt clsivs {E.cogyratexana heds). 



Trinitv division ^ ^'^"ds representing consolidated Trinity 

 ^ ' ' ' \ division. 



{Carboniferous shales and sandstones. 

 Silurian. 

 Granite. 



Trinity Sands. — The base of tlie mountains in southern Indian Ter- 

 ritory is everywhere marked by a narrow belt of excessively sandy soil 

 covered with oak timber exactly similar to that of the western Cross 

 Timbers of Texas. This is the outcrop of a formation of pack-sand iden- 

 tical in character with that of the Trinity and Paluxy sands of the Brazos 

 section in Texas, except that the limestones, which there separate them, 

 have thinned out in the country north of the Brazos. I was unable to 

 decide whether this sandy strip represented either one or both of the 

 sands of the Trinity division in Texas, and, to distinguish this Indian 

 Territory phase of these basement sands from their difierentiated charac- 

 ter as found in Texas, I shall use the provisional name of Antlers sands. 

 The Glen Rose limestones, so highly developed in Texas to the south 

 and in Arkansas to the east, do not outcrop, so far as observed, in Indian 

 Territory. 



Walnut Clays. — At one point north of Marietta the typical Walnut 

 clays (Exogyra texana beds) have a slight development below the Good- 

 land limestone, but eastward of this point they are not exposed. 



Goodland Limestone. — The Walnut clays are capped by a hard, pure 

 white crystalUne limestone to wliich the local name Goodland limestone 



