UPPER MEMBER OF KINDERHOOK 57 



axis just mentioned, the strata correlated with Hannibal shales 

 partake more of the character of a soft magnesian limestone, 

 but so earthy that it should not perhaps be termed limestone. 

 It contains some of the lead and zinc ores of the district, which 

 are now being extensively mined. On Pierson creek, seven 

 miles southeast of Springfield, in Greene county, more than 40 

 feet of this formation is exposed in mine shafts. It is overlaid 

 by 35 feet of typical buff limestone ( Chouteau ), over which is 

 the lower Burlington, here highly fossiliferous. In Ozark, 

 Douglas and Wright counties Shumard has called attention to 

 isolated patches of these shales with abundant and character- 

 istic fossils; and they are well developed in Polk county. 

 They cap the highest hills of the great Magnesian limestone 

 series, suggesting that the entire formation has been mostly 

 removed, through protracted erosion, from this part of the 

 State, perhaps as far northward as the Missouri river. 



Chouteau Limestone — the upper member of the Kinder- 

 hook — is a fine-grained, compact limestone, buff in color, and 

 usually more or less impure from an admixture of clayey ma- 

 terial. At Hannibal and Louisiana it has a thickness of from 

 10 to 15 feet, apparently thinning out rapidly northward. It is 

 probably represented at Burlington, Iowa, by a few feet of 

 buff, calcareous layers lying at the base of the great limestone 

 at that place. At Legrand, in Marshall county, Iowa, 50 feet 

 of buff magnesian limestone immediately underlying the Bur- 

 lington may perhaps be a northward extension of the Chou- 

 teau. Southward, in Missouri, the bed in question increases 

 in thickness until it attains a measurement of 100 feet or more 

 at Sedalia, and about 80 feet in the vicinity of Springfield, in 

 the southwestern part of the State. Near Ste. Genevieve 

 there are probably from 75 to 100 feet of this limestone. It is 

 quite possible that in the northwestern part of this State, far 

 below the Coal Measures, this limestone attains a much greater 

 thickness. 



(' . 



G— 5 



