$6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 149 



14 miles southeast of Baton Rouge, and at Delacroix, 3 miles south- 

 east of St. Martinville. The entrance to the bay was more than 50 

 miles wide. The head of the bay lay in St. Landry Parish near Elba 

 and in Pointe Coupee Parish near Morganza. 



In the western part of the bay drainage from the Red River built 

 a long delta, now followed by Bayou Teche, from Port Barre past 

 Leonville and Arneaudville to Breaux Bridge. Drainage from the 

 Mississippi built a delta down the middle of the bay along the Atchafa- 

 laya past Melville to Krotz Springs. Another distributary followed 

 Bayou Fordoche from Morganza to Frogmore on Bayou Grosse 

 (Fordoche quadrangle), and wider branches bordered the river from 

 Morganza to the southeast corner of the New Roads quadrangle. 



The western shore of the Pamlico bay follows the 25-foot contour 

 line on the Carencro quadrangle for 6 miles, passing 3 miles east of 

 Sunset. Here it lies at the foot of a 30-foot bluff leading to the 

 Penholoway terrace. 



Most of the bay appears to have been shallow. It probably did not 

 much exceed 25 feet in depth. 



The name Pamlico Formation was used by Stephenson (1912, 

 pp. 286, 287) for Pleistocene beds along Pamlico Sound in North 

 Carolina ". . . whose upper surface forms a low, nearly level plain 

 whose elevation nowhere exceeds 25 feet." The plain was called 

 "Pamlico terrace" on an earlier page of the same volume, by William 

 Bullock Clark, whose description was based on Stephenson's field 

 work. The Pamlico terrace has been mapped in all the states from 

 Maryland to Florida. 



At the end of the still stand at 25 feet the Gulf withdrew and 

 came to rest about 6 feet above its present level. The Pamlico 

 terrace emerged. 



Silver Bluff terrace (shore line 6 feet). — The name Silver Bluff 

 was substituted (Cooke, 1945, p. 248) for the name Miami terrace 

 (Parker and Cooke, 1944, p. 24) to avoid confusion with the Miami 

 Oolite, which is older. 



At the 6- foot level the present salt marshes along the Gulf were 

 completely submerged. A bay occupied the drowned drainage system 

 of the Atchafalaya as far north as Catahoula (Loreauville quadrangle), 

 about 10 miles northeast of St. Martinville and Crescent (Chicot 

 Lake quadrangle). At the White Castle Oil field (White Castle 

 quadrangle) it was stopped by the delta of the Mississippi, which 

 formed its eastern boundary. 



