244 Addi'ess before the Association of American Geologists. 



rejoice that the work is in such able hands, and that so many ob- 

 servers are busy at so many points, and on different sides of the 

 vast field. 



Besides the principal basin of the transition rocks just described, 

 detached deposits are sometimes met with in our country ; as for 

 example, in the eastern part of Massachusetts and Rhode Island ; — 

 and I mention this, just to say, that I have recently come to the 

 conclusion, that even that limited district probably contains, in a 

 descending order, coal measures, the old red sandstone, and be- 

 neath these, older transition strata. 



Are we to infer that the coal-bearing strata once extended over 

 the immense basin of the Mississippi, and that they have been 

 worn away, except in particular districts ? I shall not discuss 

 this question : but if the negative be true, we may still lay claim 

 probably to the largest coal-fields in the world. It is a fact of 

 great interest, also, that the coal along the eastern part of the 

 great valley, or in the vicinity of primary rocks, as has been 

 abundantly shown by Professors Rogers and Johnson, is almost 

 destitute of bitumen ; and that as we go west, it becomes more 

 and more bituminous. It is an interesting inquiry, whether the 

 coal in the vicinity of the Rocky Mountains exhibits a similar 

 change, as we recede from the chain. It is also a curious fact, 

 that gypsum and salt springs should usually be found below the 

 coal measures in this country, and not above them, as in Europe. 

 In extensive troughs of the primary rocks, along the Atlantic 

 slope of the United States, there occurs a formation of fine and 

 coarse sandstones and shales, with a predominant red color, asso- 

 ciated with beds of limestone and calcareous breccia. The most 

 extensive deposit of this group commences on the Hudson river, 

 in New Jersey, and thence pursues a southwesterly course through 

 that state, Pennsylvania, Maryland, and Virginia, into North Car- 

 olina, and perhaps beyond that state. A smaller deposit occupies 

 the valley of Connecticut river, and extends -across the states of 

 Connecticut and Massachusetts. A third deposit, according to 

 Dr. Jackson, is found in the eastern part of Maine ; and a fourth 

 has been described in Nova Scotia; where, according to Jackson 

 and Alger, it contains gypsum and salt springs, and overlies bitu- 

 minous coal. 



The lithological characters of the rocks in all these deposits, 

 are so similar, that the observer is at once satisfied of their iden- 



