80 GEOLOGY OF ILLINOIS. 



rather wet soil ; much of it consists of sandy deposits, while a portion 

 forms our very best agricultural lands. 



The loess or bluff formation does not exist to a great extent in Carroll 

 county, unless the soil and sub-soil of our productive prairies belongs 

 to this deposit. Some of our bluffs, as for instance where Johnson 

 creek breaks through to the Mississippi bottom, are composed of the 

 loess clays. 



The drift formation is also manifest in our county to a considerable 

 extent, although some seem to argue that it is undetected in the Galena 

 lead basin. Deposits of drift, in our county, can be found resting im- 

 mediately on the Galena rocks. All our little streams almost have cut 

 dowii into deposits of boulders and gravel beds. 



The following section, made in a well in the town of Mt. Carroll, 

 might be taken as a fair type of the superficial deposit resting upon our 

 rocks, beginning at the top and measuring downwards : 



Black prairie mold : 2 feet. 



Yellow, fine-graiued clay 13 



Common blue clay 2 



Reddish clay aiid gravel 15 



Tough blue clay 2 



Coarse, stratified gravel bed 3 



Pure yellow sand bed 11 



Black, mucky clay 5 



53 " 



Another well, some three miles distant, passed through a second soil 

 some fifteen feet below the surface, and immediately thereafter a depo 

 sition of timber or wood, two or three feet in thickness, many of the 

 pieces having tenacity enough to hold together for months after expo- 

 sure to the atmosphere. This well is on the farm of FELIX O'NEAL, 

 and at the time of its opening was considered an object of much interest. 



We cannot leave this part of our subject without again adverting to 

 the boulders. For us they have a peculiar charm and interest. These 

 " nigger heads," "hard heads," or lost rocks, abound in many places, 

 where the streams and rains have carried the soils away. Oftentimes 

 they are associated with gravel beds of the transported drift. Among 

 them have been found several nuggets of copper, one of which was 

 found lodged in a crevice of one of our Galena quarries. Some of these 

 boulders are striated and furrowed by the glacier or the iceberg. 

 Quartz, feldspar, granite, gneiss, hornblende, porphyry, syenite, and 

 various combinations of- these and other minerals, make up these tra- 

 veled rocks. 



Would that we could have the true history of one of these lost rocks 

 real old cosmopolitans in a primal world. What a wonderful interest 

 would cling around its wanderings from the time when it left its home 

 among the Plutonic rocks of Lake Superior, until some iceberg dropped 



