244 Address 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. es) ee 
' Besides the principal basin of the transition rocks just deseri 
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, ina 
descending order, coal measures, the old red sandstone, and be- 
neath these, older transition strata. - Vat 
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 Jargest 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 béen 
abundantly shown by Professors Rogers and Johnson, is almost 
sandstones and shales, with a predominant red persons 
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