1897.] DRAKE — THE GEOLOGY OF INDIAX TERRITORY. 381 



Permian. 



The Permian area studied lies along the western part of the field 

 and extends into it twenty to forty miles. Only about fifteen hun- 

 dred feet of Permian sediments are included in the area studied. 

 The base of the Permian deposits, as it is defined in the present 

 paper, begins with the first appearance of Permian species, and not 

 with the disappearance of the Coal Measures fauna, for that usually 

 predominates even to the highest beds studied. The strata of the 

 Permian beds consist of massive sandstones, clay shales, conglom- 

 erates and limestones. The clay shales are mostly gray and arena- 

 ceous, but toward the top they grade through blue to reddish and 

 red shales and marls. The lower two hundred to one thousand feet 

 is composed of alternating clay shale and sandstone beds in about 

 the proportion of one hundred feet of shale to ten of sandstone. 

 These beds are overlain by two hundred and fifty to five hundred feet 

 of sandstones and conglomerates, and these in turn are overlain by 

 bluish and red clay shales and marls which are interstratified with 

 occasional thin sandstones and limestones. Four generalized 

 sections, at widely separated localities, were made across these Per- 

 mian beds. The first section extends in a northwest direction from 

 Calvin to a point west of Wewoka near the western boundary line 

 of the Seminole Nation. This section will be referred to as the 

 Calvin-Wewoka section. The other three sections, with their 

 localities, are shown in PI. VIII. 



The following table gives the generalized stratigraphy of these 

 four sections : 



FEET. 



" Red and blue clay shales and 

 marls interstratified with 

 thin sandstone and very 



rare limestone beds 250 -|- 



Conglomerate and s a n d - 



stone 250 



Gray and blue clay shales 

 interstratified with thin 



sandstone 600 



{ Massive y el 1 w i s h 

 ? ■} weathering friable 

 ( sandstone 400 



Calvin-Wewoka Section. 



