256 [April, 1843. 



Petersburg, 1842. From the Imperial Mineralogical 

 Society, through Charles Cramer, Esq. 



WRITTEN COMMUNICATIONS. 



A letter was read from Dr. S. H. Dickson, dated 

 Charleston, South Carolina, March 26, 1843, acknowledg- 

 ing the receipt of his notice of election as a Correspondent 

 of the Academy. 



Also a letter from Mr. J. H. Eedfield, Corresponding 

 Secretary of the New York Lyceum of Natural History, 

 dated March 21, 1843, acknowledging the receipt of the 

 Proceedings of the Academy. 



VERBAL COMMUNICATIONS. 



Prof. Henry D. Rogers drew the attention of the Society to 

 the stratigraphical features of the environs of St. Petersburg, as 

 represented in the maps and sections appended to the volume of 

 "Publications of the Imperial Russian Society," just laid upon 

 the table. He pointed out, in particular, the perfect identity in 

 the form of the Russian anticlinal flexures and those of the 

 Appalachian chain of the 'United States; the resemblance con- 

 sisting in the want of a symmetrical curvature in the arches, and 

 an inequality in the steepness of the dips on the opposite sides 

 of the axes. 



Alluding to the structural laws first developed by his brother 

 and himself from a study of the Appalachian chain, and conceived 

 by them to characterize regions of anticlinal axes generally, he 

 proceeded to show that upon the theory of the origin of these 

 flexures, the same style of curvature should be met with in all 

 countries, as a necessary consequence of the universality of those 

 laws. The exhibition, therefore, of an anticlinal arch, having 

 the normal form, in the banks of the Pulkowka in Russia, goes 

 to conGrm the generalizations of these authors. Instances of the 

 same characteristic feature are to met with abundantly, however, 

 in the sections which geologists present of the stratification in 

 many other districts of Europe. 



