BOOXE COUNTY. 97 



Qeolo gical For m a t i o n s . 



The Cincinnati group and the upper division of the Trenton lime- 

 stones are the only rocks which outcrop, or in any manner show them- 

 selves, in this county. About its north-western comer, extending to 

 even .some distance within its borders, the middle and lower Trenton 

 limestones doubtless are the underlying rocks; but the ynowhere outcrop 

 that 1 could notice. The deposits of the Quaternary system are exten- 

 sive in the county, covering it over in many places to a great depth. It 

 will thus be seen that the geological formations of Boone county are 

 few. and its geology comparatively simple. The following section of the 

 rocks exposed and the superficial deposits, is comparatively correct; 

 although nothing but an approximation to the thickness of the latter 

 can be given : 



Section of Formations in Boone County. 

 Alluvium, principally partially stratified clays, sands and fine gravels, along the Kish waukea, 



with loams and surface soils SO feet 



Light colored, velvety, tough, tenacious, impervious potters' clay 30 " 



Ordinary drift deposits, consisting of the usual sands, gravels, hard pan and clays 35 " 



C incinnati shales : the formation much deeper, but worked to a depth of 18 " 



The Galena limestone, worked 35 " 



Lower Trenton limestones Unknown 



/S u rfa c e Geology. 



The surface geology consists of the usual Quaternary deposits, except 

 that the loess is perhaps entirely wanting. The alluvial deposits 

 along the small streams are narrow, rich and black. On the Kishwau- 

 kee they are wider and deeper, intermingled with sands and fine gravels; 

 and bear, ia places, a heavy growth of bottom timber. The usual thin 

 prairie soils, swamp mucks and peats of various degrees of purity and 

 ripeness, make up the rest. 



The drift proper is a heavy body of abraded and transported materi- 

 als. Over that part of the county underlaid by the Cincinnati shales 

 there is a thinner superficial deposit of a fine, laminated, comminuted 

 clay, of a light ashy or blue color ; bearing mingled evidence of depo- 

 sition in still waters and the dissolving in si tit of the underlying clayey 

 shale rocks. No extensive gravel beds exist; but occasional large 

 boulders may be noticed, more especially lying about the low springy 

 pla< 



But leaving the gently rolling prairies, and going northward to the 

 region underlaid by the Galena limestone, the reddish clays, hard-pan 

 and coarse gravel beds of the upper members of the drift largely pre- 

 dominate. A few miles west of Capron are localities where boulders of 

 the average size of a niairs head, lay thickly strewn over the ground. 



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