596 A. W. GRABAU TYPES OF SEDIMENTARY OVERLAP 



That this shale is not a deep-water deposit seems evident from its 

 position at the base of a transgressive series of deposits. It seems more 

 in accord with the facts to consider it a slightly reworked residual soil, 

 which had accumulated on the old limestone land surface, probably at 

 the summit of a decomposed mass of limestone, of which the brown bed 

 of variable thickness is the consolidated record. 



A section studied by Weller near Springfield, Green county, south- 

 western Missouri, and one in northern Arkansas has a significance in this 

 connection. The first of these is as follows: 



Saint Joe limestone — Burlington. Feet 



Kinderhook, consisting of 



Pierson limestone, a fine grained, buff colored limestone with 



upper Choteau fauna 3 to 10 



North View sandstone, lithically identical with the Vermicular 

 or Hannibal sandstone of the Mississippi section, but having a 

 fauna similar to that of the upper yellow sandstone of Burling- 

 ton 10 to 90 



Phelps sandstone, carrying numerous black phosphatic nodules 



and fragments of worn fish teeth, identified as Devonic to 4 



Sac limestone, a hard bluish gray compact limestone, with a 



Choteau fauna 1 to 18 



Eureka (Noel) black shale, with Kinderhook fossils to 4 



Disconformity. 



Magnesian limestone (Ordovicic). 



Weller correlates on f aunal basis the Sac limestone with the upper 

 yellow sandstone overlying the Louisiana limestone in the Burlington 

 section, or the Hannibal sandstone and Choteau limestone of the north- 

 eastern Missouri sections. Accepting this correlation as the true one, we 

 find that the overlap southward has brought the black basal shale (Eureka 

 or Noel) into the upper part of the Kinderhook formation. This is 

 borne out by the fossils of the Black shale, which are later than the 

 Chonopectus horizon. It must be remembered, however, that the north- 

 east Missouri sections are on the flanks of the Ozark uplift, and that the 

 transgression there may have been a local one. If that is the case the 

 total southward overlap is actually greater, since in the absence of the 

 Ozark uplift the actual base of the section would be lower than it is in 

 northeastern Missouri, and hence the rise of the basal black shale would 

 be from a lower position than now in the northeast to the indicated posi- 

 tion in the southwest of the state. 



In northern Arkansas the Eureka, or Noel black shale, represents the 

 same facies of sedimentation as in southwestern Missouri, and, as in that 

 section, contains fossils showing its age to be younger than that of the 



