March 15, 1895.] 



SCIENCE. 



295 



have been initiated not at tlie close of the 

 Appalachian revolution, but lonj;; afterwards 

 in Cretaceous time. Tlie Appalachian revo- 

 lution formed the mt)untains of Arkansas, 

 as well as those of tlic Alleghany belt. The 

 similarity of structure is so gi-eat that a 

 trans-ilississippian extension of Appala- 

 chian growth may be reasonably assumed, 

 as has been pointed out by Winslow (Bull. 

 G. S. A., ii., 1891, 231). The existence of 

 a bay, from the Gulf of Mexico northward 

 towards St. Louis, is very improbable as a 

 result of the Appalachian revolution ; an 

 east and west constructional mountain belt 

 is a more likely product ; and not until this 

 mountain belt was well denuded to a pene- 

 plain did a later deformation depress it 

 transversely, admitting the Cretaceous 

 waters northward across it, and thus first 

 forming the Mississippi embayment. Prob- 

 ably in part at the same time, and to a 

 greater extent in later time, the denuded 

 peneplains to the east and west were raised 

 towards their present upland altitude, and 

 as a result of this elevation the existing 

 vallej's and lowlands were opened iu them 

 during some part of Tertiarj' time. With 

 these later elevations we may associate the 

 uplift of the filled embayment and the 

 southward gi-owtli of the Mississippi as a 

 river. This view of the origin of the Mis- 

 sissippi embayment and of the date of the 

 southward discharge of Mississippi drainage 

 was first published by L. G. Westgate 

 (Amer. Geol. xi., 1893, 251), as a result of 

 conference with L. S. Griswold, who had 

 then recently completed his investigation of 

 the novaculite region of Arkansas. 



THE CUUNNENUGGA RIDGE AND THE BLACK 

 PRAIRIES OF ALABAMA. 



It is. perhaps, too much to expect that the 

 origin of the physiographic features of a 

 region should always receive due attention 

 in a geological report along with the origin 

 of its strata ; j-et there is no other place so 



appropriate for the official publication of 

 phj'siogi-aphical discussions. It therefore 

 occasions regret to find so little account of 

 the origin and meaning of the Chunnenugga 

 ridge and the Black prairies of Alabama in 

 the elaborate report on the Geology of the 

 Coastal Plain lately published by the Survey 

 of that State. " The Chunnenugga ridge is 

 made in great part by alterations of hard 

 limestone ledges and bands of indurated 



sands of the Eipley It overlooks 



the low trough of the black prairies of the 

 Rotten limestone towards the north with 

 somewhat precipitous slopes in that direc- 

 tion, while its descent towards the south is 

 much more gentle" (p. 856). It is mani- 

 fest that the ridge wdth its inland-facing 

 escarpment and the denuded inner lowland 

 are typical features of a certain stage in the 

 denudation of a coastal plain that consists 

 of more and less resistant strata ; the drain- 

 age of the lowland being chiefly gathered 

 by subsequent streams that have been de- 

 veloped along the strike of the beds, and dis- 

 charged by consequent streams which main- 

 tain transverse valleys through the enclos- 

 ing ridge or upland. Tliis genei-al relation 

 of form and drainage is so often repeated on 

 coastal plains that its occurrence in Alabama 

 deserves mention as a local example of a 

 general physiographic feature ; just as the 

 Cretaceous strata on which it is developed 

 deserve mention as local examples of a wide- 

 spread geological formation. 



W. M. Davis. 

 Harvard University. 



THE NEW YORK MEETIXG OF THE ASSOCI- 

 ATION OF AMERICAN ANATOMISTS. 



The Seventh Annual Session of the Amer- 

 ican Anatomists was held in the Medical 

 Department of Columbia College, 437 West 

 59th Street, Xew York City, December 28 

 and 29, 1894. 



The Association was called to order Fri- 

 daj', December 28th, by the Presidi-nt, Dr. 



