EPICONTINENTAL SEA OF JURASSIC AGE 243 
area. Many of these terms have been used in a loose geographic 
sense since the object is to include under one name all of the 
minor localities belonging to one areal province. The numbers 
on the map’ indicate the position of these areas. 
THE SOUTH CENTRAL WYOMING AREA 
The Freeze-Out Fiills.?—The oldest rocks recognized in the 
Freeze-Out Hills are the Carboniferous. They occupy the cen- 
ter of the partly dissected anticline and are overlain by the Red 
Beds which are composed of sandstones and reddish arenaceous 
clays and marls inclosing here and there lenticular masses of 
gypsum or gypsiferous clays. These beds are seemingly devoid 
of fossils and are apparently conformable with the overlying 
Jurassic beds of unquestionable marine deposition. At a point 
on the Dyer Ranch the following stratigraphical conditions of 
the contact between the Red Beds and the Jura were noted in 
ascending order :3 
Ipebase wear toprorctne Wed Beds) reddish clay. )2) a: 
White, indurated sandstone, 4” ; 
Clay iiehtared as 
White sandstone with a reddish tinge, 1’; 
Wight red! clay, 27 ; 
White, slightly indurated sandstone, 6° ; 
Shale, reddish changing to purple, 4’ ; 
White fissile arenaceous limestone, 0’ ; 
Arenaceous clay of,a dull red color, 10’ ; 
oO © ON Am WwW DN 
_ 
White laminated arenaceous limestone containing fossils, 
OV 
This last stratum contains a characteristic Jurassic type, 
Pseudomonotis curta Hall. This is the first or lowest known fossil 
bearing horizon of the Jura in this area. Any division line 
between the Red Beds and the Jura placed lower than this fossil 
bearing stratum would be an arbitrary one as there appears to 
be no unconformity to mark the separation. To the beds occur- 
ring above the fossiliferous horizon the term Jura-Trias is no 
aISee ps 2415. 2LoGaN: Kansas Uni. Quart., April 1900. 
3 Quoted from paper mentioned above. 
