242 Address before the Association of American Geologists. 
this interesting metal will ere long be obtained from our own 
mountains. 
You will perceive that under the term primary rocks I have 
included none that are fossiliferous. The latter, especially those 
usually denominated transition, have, as is well known, an im- 
mense developement in our country. A single vast basin, ex- 
tending from the Apalachian chain nearly to the Rocky Moun- 
tains, and from the centre of Alabama; in a northern direction, 
perhaps even to the Arctic sea, not less than two thousand 
miles long and twelve hundred broad, and consequently covering 
about two and a half millions of square miles ;—this wide region 
forms almost one uninterrupted deposit of older secondary or tran- 
sition rocks; the largest undoubtedly on the globe. Until re- 
eently, these rocks could be described only under the vague 
designation of graywacke. But light is beginning to shine in 
upon the chaos. ‘The upper member, that which embraces the 
bituminous and anasphaltic coals of Pennsylvania, Ohio, Indiana, 
Illinois, Michigan, and Missouri, seems now to be well identified 
with the coal measures of Europe. . This forms a convenient 
starting point, and all that remains is to compare the groups be> 
low the coal, with those similarly situated in other parts of the 
world. Professors Henry D. and William B. Rogers have divi 
ded this vast series into twelve formations; and these, including 
the coal measures, which make the thirteenth formation, they 
find to be not less than forty thousand feet thick. Whatever 
may be their views as to the identity of these groups with rocks 
described in other parts of the world, they have refrained from 
expressing an opinion, in their annual geological reports. But 
other gentlemen suppose they have discovered marks of identity, 
in respect to several of the groups, too strong to be resisted. It 
is difficult to read the reports of the Ohio geologists, especially 
that of Dr. Locke, and those of Dr, Houghton, Mr. Featherston” 
haugh, Prof: Troost, and that of Dr. Owen on the. mineral-Jands 
of Wisconsin and lowa, and: that of Mr. Conrad on the New 
York survey for.1841, without being convinced that the ¢aF 
boniferous or mountain limestone is extensively developed from: 
Pennsylvania westward at least fifteen hundred miles; W 
