UPPER PART OF AUGUSTA 69 



Those who have personally collected and investigated in 

 the middle portions of the Lower Carboniferous rocks of the 

 southwestern part of Missouri have all found great difficulty in 

 attempting to divide the Augusta limestone in the same manner 

 as in the northeastern portion of the State. Whenever mention 

 has been made of the Keokuk, in connection with the encrin- 

 ital limestones of this region, it has always been in the most 

 vague and uncertain manner. Of late years, collectors who 

 have visited the southwestern lead and zinc districts have 

 assumed that there the Burlington and Keokuk faunas are 

 mingled or blended so as not to be distinguishable. In accord- 

 ance with the idea, various field names have been given by 

 different collectors to the rocks as developed in this part of 

 the State, the most prevalent one now being " Cherokee." The 

 same idea is embodied in the selection of the designation 

 "Osage " for the group, a geographic name pertaining to this 

 region. 



As already shown in another place, insofar as the Burling- 

 ton is concerned there is, in Greene and Dade counties espe- 

 cially, as well as in other neighboring districts, an Upper and 

 Lower Burlington fauna identical with, and as well defined as, 

 the two faunas are at the typical locality in southeastern Iowa. 

 Warsaw Beds, — The Warsaw beds as defined by Hall* 

 and as exposed at the village of Warsaw, Illinois, are composed 

 ( 1 ) 10 feet of compact, buff-colored limestone at the base ; ( 2 ) 

 30 feet of blue calcareous shales with thin limestone seams, 

 and {3) S feet of yellow arenaceous limestone. At Keokuk, 

 five miles above, all three layers are thinner, and at neighbor- 

 ing places they exhibit still different characters. Southward 

 the beds lose their argillaceous nature, and appear not to be 

 separable from the associated limestone. These layers together 

 with the " geode bed," which is usually considered the upper 

 member of the Keokuk, may be regarded as mere local devel- 

 opments, to which little importance is to be attached. In a 

 quarry a short distance northwest of Eand park, at Keokuk, 

 Iowa, there is a good exposure showing the upper surface of 



*Geology of Iowa, Vol. I, p. 971. 858. 



