482 



SCIENCE. 



[N. S. Vol. XXIII. No. 587. 



and I might add that my personal ac- 

 quaintance with these formations in Ala- 

 bama is much larger than in the other 

 states concerned. 



CRETACEOUS. ' 



In the Cretaceous, the principal advance 

 seems to have been the discovery or dis- 

 crimination of a lower division, represented 

 in Texas, the Indian Territory and Ar- 

 kansas by the Comanche series, and in the 

 Gulf states east of the Mississippi, by the 

 Tuscaloosa formation. 



The Comanche includes in ascending order, 

 three groups, the Trinity, the Fredericksburg and 

 the Washita. By mfeans of its flora the Tusca- 

 loosa formation has been correlated with the 

 Raritan formation of New Jersey, which is placed 

 at the top of the Lower Cretaceous (Potomac 

 group) of that region. A somewhat similar un- 

 studied flora occurs in the Cheyenne sandstone 

 of southern Kansas, which is certainly in the 

 upper portion of the Comanche series and prob- 

 ably within the Washita group. The Tuscaloosa, 

 therefore, seems to be about on the horizon of the 

 Washita group and may represent it in whole 

 or in part.' 



The Tuscaloosa strata were well and 

 fully described by Hilgard in his 'Geology 

 of Mississippi, ' but both by himself and by 

 Tuomey, of Alabama, were included in 

 their Eutaw formation, as its lowest mem- 

 ber; but subsequent study in Alabama, 

 especially of the plant remains of the for- 

 mation, led to the separation of these beds 

 from the other Eutaw strata and the estab- 

 lishment of their equivalencies .as above 

 indicated. 



It has also been recently shown that very 

 much of the Rotten Limestone division of 

 the Cretaceous is largely composed of for- 

 aminiferal shells and is, therefore, of the 

 nature of chalk, and in Alabama the name 

 Selma chalk has been given to it. 



It may further be noted as a matter of 

 interest that the suitability of the purer 



' T. W. Stanton, .letter of November 1, 1905. 



beds of this chalk as material for the manu- 

 facture of Portland cement has been amply 

 demonstrated by the success of the Demop- 

 olis (Alabama) cement plant. 



TERTIARY AND LATER FORMATIONS. 



These I prefer to consider together, for 

 the reason that the precise line between the 

 Tertiary and post-Tertiary can hardly be 

 said to be definitely fixed as yet. 



Since 1881 much geological work has 

 been done in the Tertiary formations of 

 Alabama, especially in the beds below the 

 Lower Claiborne or Buhrstone (the North- 

 ern Lignitic of Hilgard), and their strati- 

 graphic relations along the Tombigbee, 

 Alabama and Chattahoochee rivers have 

 been carefully worked out, and described 

 in Bulletin 43 of the United States Geo- 

 logical Survey, and more fully in the Re- 

 port on the Coastal Plain of Alabama, pub- 

 lished in 1894, by the Geological Survey 

 of Alabama. 



While in Mississippi in these lower beds 

 the lignitic character is more pronounced, 

 in Alabama the marine facies is better de- 

 veloped, and the existence of a number of 

 beds with well-preserved marine shells lias 

 made possible a greater degree of differ- 

 entiation than could be obtained in the 

 adjoining states; though several of these 

 marine deposits of the Alabama Lignitic 

 have been traced into Mississippi on the 

 one hand, and into Georgia on the other. 



In 1880, while acting as special agent 

 of the tenth census, the present speaker 

 showed that the Vicksburg limestone was 

 the underlying formation of the Florida 

 peninsula down nearly to the Everglades, 

 and that this limestone at a number of 

 points was overlain by another limestone 

 or marl containing Miocene shells.^ 



The Miocene localities then observed 

 were, however, mostly on the Atlantic side 

 of the peninsula, to which region our in- 



^ Vol. VI., Quarto Reports, Tenth Census. 



