32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 



extended across Louisiana into Arkansas (fig. 16). An eastern prong 

 reached up Tensas Bayou into Madison Parish, La. The upper part 

 was bounded on the east by the delta of the Mississippi, which 

 pushed down below Grand Gulf, Miss. The western shore lay west 

 of Bayou Macon. This eastern prong was separated from the drowned 

 valley of the Ouachita by a low-lying peninsula of Wicomico terrace 

 that extended southward beyond Leland into Catahoula Parish. 



The western prong of the Penholoway bay forked near Monroe, 

 La. One wide branch followed Bayou La Fourche almost to Collins- 

 ton; the other pushed up the Ouachita into Arkansas beyond the 

 mouth of the Saline River, with a narrow place near the town of 

 Ouachita, in Union Parish. Tidewater also reached up Bayou d'Ar- 

 bonne and Bayou l'Outre. 



At Harrisonburg the shore turned southwestward along the high- 

 land west of Bushley Creek and Catahoula Lake, where it curved 

 southeastward to the expanded Gulf of Mexico in Avoyelles Parish 

 near Long Bridge. 



In the western part of Evangeline Parish the shore of the Gulf 

 followed the boundary line between the "Montgomery Formation" and 

 the "Prairie Formation" as mapped by Varvaro (1957, pi. 1). Pre- 

 sumably, therefore, the "Prairie terrace deltaic surface" of Varvaro 

 (1957, p. 37) is equivalent, at least in part, to the Penholoway 

 terrace. 



The eastern shore of the Penholoway bay lay not far east of the 

 Mississippi River from Grand Gulf, Miss., to a projecting cape at 

 Alsen, about 4 miles north of Baton Rouge, where it met the Gulf. 



The State Industrial School for Boys at Alsen ( Scotlandville, La., 

 quadrangle) is built on the Penholoway terrace near the shore of a 

 cove that curves eastward past Baker, which stands on the Wicomico 

 terrace just above the Penholoway shore (fig. 17). The greater part 

 of the city of Baton Rouge is built on the Penholoway terrace, but 

 the southern part steps down to lower terraces (fig. 18). 



The Penholoway terrace was named by Cooke (1925, p. 24) from 

 Penholoway Creek and Penholoway Bay (a swamp) in Georgia. It 

 was further defined by reference to a shore line at 70 feet (Cooke, 

 1931, pp. 505, 509). It has been mapped in Georgia (Cooke, 1939b, 

 1943), South Carolina (Cooke, 1936), and Florida (Cooke, 1945). 



After the sea withdrew from the 70- foot level it came to rest at 

 42 feet. 



Talbot terrace (shore line 42 feet). — During the 42-foot stage of 

 the Gulf (fig. 19) the mouth of the Talbot bay lay between Baton 



