CAKB0NIFE110US LIMESTONES OF IOWA. 



101 



land. The prairie-sod, matted and deep-rooted, usually requires from six to eight 

 yoke of oxen effectually to break it up. 



The future farms of Iowa, large, level, and unbroken by stump or other obstruc- 

 tion, will afford an excellent field for the introduction of mowing and reaping 

 machines, and other improved implements calculated to save the labour of the 

 husbandman ; and which, in new countries reclaimed from the forest, can scarcely 

 be employed until the first generation shall have passed away. 



The curious and remarkably symmetrical mound-like form of some of the outliers 

 of the Carboniferous Limestone on the northeastern side of the basin, beyond the Forks 

 of the Iowa, are so extraordinary, that they have been deemed worthy of illustration. 



OUTLIER OF CARBONIFEROUS LIMESTONE, IOWA RIVER. 



SECTION VI. 



THEIR LOCAL DETAILS. 



Carboniferous Rocks of the Iowa River. — After leaving Township 81 north, 

 Range 8 west, no rocks were seen in place near the river for about fifty miles in a 

 direct line, and nearly double that distance by the river, which is very tortuous in 

 its course. The deep alluvial and drift deposits effectually conceal the strata on 

 which they rest. It is only from the angular fragments of chert occasionally seen 

 strewn on the elevated ground, that any clue is obtained to their age ; this mineral 



