192 



GENEKAL GEOLOGY. 



Section of Kinderhook Beds at Burlington. 



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to this lowest formation of the Sub-carboniferous group, its 

 specific designation is modified as in the preceding heading. 



The term beds is literally very appropriate to the formation 

 as it exists in Iowa, because at its typical localities here it is 

 made up of a series of alternating beds of sandstone and 

 limestone, the majority of which are comparatively thin. 

 The section, represented by fig. 6, shows its lithological com- 

 position at Burlington, where it is more fully exposed than at 

 any other point in the State, and where also its characteristic 

 fossils are most abundant. 



Bed No. 1 of this, section is Fig-. 6. 



largely composed of fine grained, 

 sandy shales, but varying from 

 bluish, clayey shale, to fine 

 grained, yellowish sandstone. 

 The greatest thickness of this 

 bed yet measured in actual 

 exposure is eighty -two feet, but 

 by artesian borings made in the 

 city, it is recognized with cer- 

 tainty at a depth of sixty-five 

 feet beneath that measurement^ 

 making the recognized thick- 

 ness of the whole to be one 

 hundred and forty-seven feet. 

 Further prosecution of the bor- 

 ings at Burlington, made by Mr. 

 Bosch, are reported to have 

 passed through " two hundred 

 and fifty feet in all of blue clay " 

 beneath the level of the water 

 in the Mississippi river. This, 

 like the results of all borings of 

 the kind, is not entirely satis- 

 factory, and yet it is not impro- 

 bable that Bed No. 1 has a much 

 greater thicknesss than is indi- 

 cated in the foregoing section. 



The upper portion of this bed 

 is, in some places, quite fossil- 

 iferous, the fossils being mainly 

 in the form of casts and largely 

 confined to Larnellibranchiates and Brachiopods. 



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'200ft 



