DALE OWEN ON THE WESTERN STATES OF NORTH AMERICA. 435 



La Salle county, Illinois, a distance of 325 miles ; and from S.W. 

 to N.E., from St. Louis and the waters of the west branch of 

 Saline river in Gallatin county, Illinois, to the forks of Fox river 

 and Kankakee river, a distance of 250 miles. This gigantic coal- 

 field occupies the greater part of Illinois, about one-third of Indiana, 

 a north-western strip of Kentucky, and extends a short distance into 

 Iowa. Its boundaries have been satisfactorily ascertained, except a 

 small segment in the Burlington district of Iowa, which I have not 

 yet personally explored. That portion of the outline of this and 

 other formations which I do not consider fully determined is dotted 

 on the map. The coal-field is covered in many places in the north 

 by extensive diluvial deposits, sometimes to the depth of more than 

 100 feet. 



The other coal-field of which I have spoken forms a part of at 

 least six states, viz. Ohio, Kentucky, Tennessee, Pennsylvania, Ma- 

 ryland and Alabama ; but that portion of it embraced in the three 

 former is alone represented on the map, stretching along its eastern 

 portion. The geologist of Ohio, on whose authority its boundaries 

 in Ohio and Kentucky are there given, estimates its area at 50,000 

 square miles. The eastern confines of this coal-field in Tennessee 

 are defined on the map, but it is to be remarked, that further north 

 it extends to the eastward beyond the limits of the map, and also 

 for a very short distance south of Tennessee into Alabama. Dr. 

 Troost, according to whom its boundaries in Tennessee are given, 

 remarks, in his Third Annual Report, that the localities in which 

 we may expect to find coal in that state, belong exclusively to the 

 Cumberland range of mountains. These coal-formations consist, as 

 in Europe, of sandstones, shales, slaty clays, seams of coal, and oc- 

 casionally beds of limestone, the latter usually dark-coloured and 

 bituminous. 



At the base of the Ohio formation is a conglomerate from 200 to 

 300 feet in thickness, which has been referred to the millstone grit 

 of England. A similar conglomerate shows itself in one or two lo- 

 calities at the base of the Illinois coal-field, but in general it is not 

 present as a conglomerate. 



The thickness of these coal-fields is estimated at from 1200 to 

 2000 feet. The Ohio geologists report at least seven workable seams 

 of coal, besides ten or twelve minor beds ; and the Illinois field is 

 supposed to include also seven workable seams. All the coal is of 

 a bituminous character; some of the caking variety, some splint 

 coal, some cannel. The upper seams appear to be thinner than the 

 lower, and inferior to them in quality. In some of tiic upper scams 

 in Indiana I have observed the woody structure displayed so very 

 distinctly, that I succeeded in separating its fibres, as one might in 

 charcoal. 



Neither of these coal-fields has suffered much from dislocation. 

 No dikes of trap, whinstono, basalt or greenstone hav(^ met my ob- 

 servation in the Illinois coal-basin; nor do the Ohio g(>ologists make 

 mention of any such in their state. On the eastern Hank, however, 

 of the Cumberland mountains, the coal is occasionally much (lis- 



