144 Prof. Rogers's Address before the 



read to the American Philosophical Society, describing a number of mi- 

 nute species ; and Mr. Conrad has figured some interesting species col- 

 lected by Mr. Hodge in North Carolina and by himself in Maryland. 

 Prof. William B. Rogers has during the last two years traced exten- 

 sively the tertiary infusorial stratum of Virginia, while Profs. Bailey and 

 Ehrenberg have discerned in this material a great multitude of curious 

 microscopic forms. Mr. J. Hamilton Couper of Georgia has written on 

 the bones of certain fossil mammalia in that state ; and Mr. Lyell has 

 published a paper (Proceedings of the Geological Society of London) 

 on the position of the Mastodon giganteum and its associated fossils in 



Kentucky and elsewhere. 



Several papers on topics in geological dynamics and in chemical 

 geology have also appeared. Thus the complicated and interesting 

 question of the origin of the vast drift formation of this continent, has 

 been discussed by Dewey, Emmons, Hall, Hitchcock, Jackson, Mather, 

 Vanuxem, and by my brother and myself, so that it may be said, that 

 we are now in possession of the observations and theoretical views 

 of most of the investigators of this curious deposit. The laws of 

 earthquake motion, the explanation they offer of the origin of anticli- 

 nal flexures and folds in strata, and the elevation of mountain chains, 

 and the aid which the same views afford in accounting for the facts COn- 

 nected with our coal strata, with the drift and other formations, have 

 been in several shapes submitted to the geological world by my brother 

 and myself. Mr. J. D. Dana has read at our last meeting a paper con- 

 taining a theory of the metamorphism of rocks, attributing their schis- 

 tose structure to crystallization, and ascribing their alteration by heat to 

 " the heated waters of a surrounding ocean." Two papers were read 

 on the same occasion, by Prof. Lewis C. Beck, one " on certain phe- 

 nomena of igneous action chiefly observed in the state of New York, 

 in which the author arrives at the interesting conclusion that certain 

 rocks have been subjected to a high temperature subsequent to the for- 

 mation of the minerals in them, by which these were softened and de- 

 ranged in shape. The other paper was on the ancient climates of the 

 globe. Our volume of Transactions contains a paper, by Mr. Vanux- 

 em, on the origin of mineral springs, and one by Prof. William B. R°g* 

 ers on the connection of the thermal springs of Virginia with anticlinal 

 flexures and faults. To Prof. Bailey we were indebted last year, for a 

 paper on the crystals formed in the tissues of dicotyledonous plants, and 

 a valuable report was submitted to the Association at the same meeting* 

 by Mr. John L. Hayes, on the transportation of detrital matter, by ice- 



