332 TRANS. ST. LOUtS ACAD. SCIENCE. 



The relations of the more important members of this series 

 both among themselves and to the surface are shown graphically 

 in the general section through the tract surveyed forming Fig. 6. 



The relations of the series as a whole to the subjacent forma- 

 tions are roughly indicated by the boring record. While it is 

 evident from the record, and still more from the borings them- 

 selves, that samples were not taken with sufficient frequency to 

 give an accurate sequence, inspection shows that borings brought 

 up from beneath the summit of the first heavy limestone fall natu- 

 rally into nine groups, viz. : 



Group. Petrographic Character. 



1 Limestones 



2 Somewhat calcareous shales 



3 Cherty limestones and associated shales 



4 Nodular calcareous shales 



5 Silicious limestones, calcareous shales, etc., 



of heterogeneous character 



6 Shalj and non-silicious limestones 



7 Cherty limestones passing into shales 



8 Shales or indurated clays 



q Sandstone 



T'axouofny. — The time at disposal did not permit, and the exi- 

 gencies of the investigation did not require, sufficiently extended 

 collection of fossils or of stratigraphic data to warrant correlation 

 of the Macon county series of deposits with those of other re- 

 gions. It was found, indeed, that the fossils are of little value 

 in identifying the several beds in which they occur, partly no 

 doubt because they were not collected and studied with sufficient 

 care, but partly because the same genera and species occur at 

 various horizons wherever the strata are of like composition. 

 Thus Cho7ietes mesoloba* is found in equal abundance in two 

 beds separated by a vertical interval of over 70 feet in Macon 

 county, and, according to White, ranges '^ through the whole se- 

 ries of strata of the Carboniferous period in Illinois, Missouri, and 

 Iowa";t while Product us ivquicostatns^ whose type comes from 



* Identified by Mr. CD. Walcott, Palaeontologist U. S. Geological Survey. 



t Rep. Geog. and Gaol. Expl. and Surveys W. of the looth Mer., iv. pt. i, 1S75, 123. 



