Carboniferous System of the United States. 415 



As the geological examinations of our country were extended, 

 and when the more methoJical and scientific measures were 

 adopted of connecting every line of examination with a regular 

 system of levelling, added to palgeontological investigations, it 

 was found that some of the coal basins of the States of Michigan, 

 Iowa, Missouri, and Northern Illinois, had not this Conglomerate 

 developed, or at least that it could not be identified ; but in 

 some instances, as at La Salle, on the Illinois river, the Con- 

 glomerate was a rock belonging to a far earlier age. 



The brothers Rogers, in their investigations in Vii-ginia, 

 found in Wythe, Pulaski, and Montgomery counties two or 

 three thousand feet of green and red shales, containing three ov 

 more workable strata of coal, lying below their basal " forma- 

 tion No. XII." Mr. Lesley made a similar discovery in Blair 

 county, Pennsylvania, at the head of the Juniatta river, where 

 he found six hundred feet of shales, below the " No. XIL," con- 

 taining three workable seams of coal. The late Dr. Owen made 

 similar discoveries in the States of Kentucky and Arkansas. In 

 Northern Illinois and Iowa, in the black shales of the horizon 

 of the Portage Group of the New York system, workable seams 

 of coal have been found. This shale contains land plants, and 

 is highly charged with bitumen, and is the source of the petro- 

 leum and gas springs of New York, Canada, Northern Penn- 

 sylvania, and Ohio. When we add to these numerous instances, 

 amounting almost to a law, that Prof. Dawson found a similar 

 system of coal measures, below the Formation No. XIL, in his 

 geological exploration of Nova Scotia, are we not carried back 

 towards the opinions of the Fathers of American Geology ? 



Why should a certain coarse conglomerate, grading ofi" into 

 a sandstone, seldom to be distinguished from any other con- 

 o-lomerate and sandstone lying either above or below it, by any 

 palffiontological — the only true evidence, and never by any litho- 

 loo-ical evidence, be considered the basal measure of the carbo- 

 niferous? Far below lie true coal-bearing strata. Long ages 

 previous to its being laid down, the continent was clothed in 



DEC, 1861. 29 Ann. Lyc. Nat. Hist. Vol. VII. 



