92 Review of Owen’s Geological Report on Wisconsin, Towa, ete. 
The carboniferous rocks which form the subject of the 3d 
chapter, lie southwest of the above formation, occupying nearly 
the whole of the remaining portion of Southern Lowa, and ex- 
tend from the Mississippi across to the Missouri. 
The coal-measures, without the circumscribing belt of carbon- 
iferous limestone, occupy in Iowa alone 25,000 square miles, 
extending no less than 200 miles in a direct line up the Des 
Moines, which river flows diagonally through the heart of that 
portion of the coal-field which is situated in Iowa. The same 
coal-field stretches into Missouri, in which state it has at least as 
great an area. ; 
e coal measures are underlaid by a great zone of sub-car- 
boniferous limestone, the average width of which may be 20 to 
miles, except in the extreme northeast, where the sandstones 
+ ~~ coal formation abut immediately on the limestone of Cedar 
alley. 
the beds varying from a few inches to 43 or 5 feet. They are 
included in the shaly argillaceous division of the lower third of 
the formation. ‘There are beds of greater thickness farther south 
in Missouri, at the southern margin of the same coal-field. - 
Under the head of “Physical and Agricultural character” of 
the carboniferous rocks of Iowa, the author makes the following 
rema’ 
* The carboniferous rocks of lowa’occu py a region of country, which, 
taken as a whole, is one of the most fertile in the United States. “No 
that of the Cedar Valley, returns him reward for his labor a hundred- 
fold. The only drawback to its productiveness is that, on some of the 
higher grounds, the soil, partaking of the mixed character common to 
drift soils, is occasionally gravelly ; and that here and there, where the 
upper members of the coal-measures prevail, it becomes somewhat too 
siliceous. 
The rural beauty of this portion of Towa can hardly be surpasssd. 
Undulating prairies, interspersed with open groves of timber, and 
some skirted with timber, some with banks formed by the greensward 
of the open prairie ;—~these are the ordinary features of the pastoral 
ape. 
For centuries, the suceessive natural crops of grass, untouched by 
the scythe, and but very partially kept down by the pasturage of buffalo 
and other herbivorous animals, have accumulated organic. matter on 
