588 D. W. LANGDON, JR. — CRETACEOUS AND TERTIARY STRATA. 



logical Survey, have given the following classification, subdivision and 

 thickness of these formations : 



Feet. 



f r Coral Limestone (Vicksburg?) 150 



Upper \ Vicksburg (Orbitoidal) 140 



( White Limestone.) [ Jackson ' 60 



Tertiary ■< 



(Eocene.) 



Middle . 



Loioer 



Claiborne - 

 Bubrstone 



140-145 

 300 



f Hatcbetigbee 175 



Wood's Bluff or Basbi 80-85 



I Bell's Landing or Tuscaboma 140 



\ Nanafalia 200 



Matthews' Landing or Nabeola __ 130-150 



I Black Bluff 100 



[Midway 25 



Cretaceous 



Cretaceous (?) 



Kipley 



Rotten Limestone. 

 Eutaw 



250-275 

 ., 1,000 

 ._ 300 



.Tuscaloosa- 



(?) 1,000 



The measurements, actual and estimated, for the foregoing table are the 

 result of careful observations made during boat trips down the Tombigbee, 

 the Tuscaloosa, and the Alal)ama rivers, and wagon excursions through the 

 regions embraced in the drainage of these streams. It was the privilege of 

 the wTiter to be associated with Professor Smith in the greater part of this 

 work, so that personal acquaintance with these formations as determined 

 by Professor Smith under the auspices of the Alabama geological survey, in 

 the western part of Alabama, renders it possible to compare them with 

 those of the Georgia border with some degree of accuracy. 



The summers of 1886 and 1887 were spent by the writer in tracing the 

 Cretaceous and Tertiary rocks to the state line between Alabama and 

 Georgia, and in determining the sections of strata exposed by Conecuh, Pea, 

 and Chattahoochee rivers. It is the purpose to show in this paper the 

 variations in the strata due to different conditions of sedimentation, as well 

 as the faunal changes, together with unconformities brought about by the 

 total absence in this region of groups well defined in the western part of the 

 state. 



The strata will be taken up in the order of their deposition, though the 

 sections are in reverse order — i. e., the latest stratum at the top. 



Cretaceous Strata. 



The Tuscaloosa. — As early as 1846 the beds of pebbles wdth the associated 

 deposits of clay were referred to the lower Cretaceous,'!^ although Tuomey 



* Quart. Jour. Geo]. Soc. Lond., vol. 2, p. 280. 



