142 Prof. Rogers's Address before the 



New York strata through the western part of Upper Canada and the 

 adjacent districts of Michigan and Ohio, was briefly sketched in a paper 

 laid before the American Philosophical Society in 1842, by my brother 

 and myself; while to Dr. Troost's last Annual Report on Tennessee, 

 published in 1841, we are indebted for some interesting additions to our 

 knowledge of the Palseozoic rocks in that state. A short communica- 

 tion made by Dr. Clapp of New Albany in Indiana, to the Academy of 

 Natural Sciences of Philadelphia, has also contributed to assist in the 

 identification of the western with the eastern states. 



The Appalachian coal strata of Pennsylvania, Ohio, Maryland, Vir- 

 ginia, Kentucky and Tennessee, bituminous and anthracitic, have been 

 compared and traced, and a theory of their origin ventured upon in a 

 paper by myself, submitted to this Association ; and my brother and 

 myself have also presented a memoir on the Physical Structure of the 

 Appalachian chain. 



The areas occupied by the palaeozoic strata have been already care- 

 fully delineated in geological maps, for a large portion of the United 

 States, this side of the Mississippi. Thus we are in possession of an 

 excellent map of the state of New York by the state geologists, and 

 one on a small scale of Ohio, Indiana, Illinois and Kentucky by Law- 

 rence. A map of the last named states, including also middle and west- 

 ern Tennessee, has likewise been carefully compiled, principally from 

 personal observation by Dr. Owen, and gives us the most exact picture 

 we yet possess of the distribution in that region of the several groups of 

 our palaeozoic strata under their western types. The information con- 

 veyed by it has been fully imparted, though the map has not, I believe, 

 been yet published. The palaeozoic formations of New Jersey and Penn- 

 sylvania have been mapped by myself and my assistants, those of Mary- 

 land by Dr. Ducatel, and my brother and myself, while those of Vir- 

 ginia have been minutely delineated by my brother and his corps, in tlie 

 survey of that state. But the geological maps of Pennsylvania, Mary- 

 land and Virginia have not yet been published. To Mr. Conrad we owe 

 the approximate tracing of the southern border of these formations in 

 Alabama. At our last meeting a valuable paper was read by Mr. James 

 Hall, on the geographical distribution of the fossils of the palaeozoic 

 rocks of the United States, and another on the geological and geo- 

 graphical distribution of the Crinoidete of the older rocks of New 

 York. 



Our knowledge of the Mesozoic strata of the United States has been 

 considerably advanced by publications issued during the two or three 



