SHAW: NEW AREA OF CARBONIFEROUS 553 



vieve and Commerce, Missouri, to Shawneetown and Golconda, 

 Illinois. The various formations of the Gulf embayment have 

 concentric areas of outcrop, the oldest extending farthest north, 

 and, according to the maps, terminating rather abruptly, as 

 though the south side of the range of hills were a cliff cut by the 

 waves of a Cretaceous sea. The general arrangement of out- 

 crops of the 'Paleozoic formations is also concentric but convex to 

 the south, so that the outcrops of the older formations are nearest 

 the Gulf embayment. 



The Provisional Geologic Map of Illinois, compiled by Stuart 

 Weller 2 and published in 1906, represents the Gulf embayment 

 deposits in Illinois as consisting of Tertiary (possibly including 

 some Cretaceous) shales, fire clays, sands, and gravel, and the 

 northern border is along the middle of the abandoned Ohio val- 

 ley, except that at the east end it curves south through Temple 

 Hill and Rosebud to the present channel of the Ohio at New 

 Liberty (all villages in southern Pope County) and at the west 

 it curves south through Tamms to Santa Fe. 



In the same year Glenn 3 published a map that shows all of 

 the Gulf embayment area in Illinois as Cretaceous except the 

 southern part of Alexander and Pulaski Counties just north of 

 Cairo. The northern boundary is roughly similar to that on 

 Weller's and other earlier maps but slightly more wavy. A little 

 south of the middle of Alexander and Pulaski counties is an east- 

 west belt of Porters Creek (Eocene), about 3 miles wide and 

 slightly convex to the north; and south of this belt, these coun- 

 ties are, according to this map, underlain by LaGrange (Eocene). 



The geologic map of North America by Willis and Stose 4 

 is similar to that of Glenn except that the two Eocene formations 

 are grouped together. 



2 Weller, Stuart. The geological map of Illinois. Illinois State Geol. 

 Survey Bull. 1. Pp. 26 and geol. map. 1906. 



3 Glenn, L. C. Underground waters of Tennessee and Kentucky west of Ten- 

 nessee River and of an adjacent area in Illinois. U. S. Geol. Survey Water-Sup- 

 ply Paper 164: PI. 1. 1906. 



4 Willis, Bailey, and Stose, G. W. Geologic map of North America. Scale 

 1:5,000,000, U. S. Geol. Survey in cooperation with Canada Geol. Survey and 

 Inst. Geol. de Mexico, 1911. Published also in U. S. Geol. Survey Prof. Paper 

 71, in 4 sheets and in separate case, 1912. 



