374 D. K. Greger — Devonian of Central Missouri. 



Art. XXX. — The Devonian of Central Missouri; by 

 Darling K. Greger. 



The Devonian of central Missouri is a two-fold formation of 

 somewhat variable thickness and in the region of its greatest 

 development it consists of more or less heavy-bedded, blue, 

 gray and reddish-brown limestones, and of coarse, blue and gray 

 shales and shaly limestones, the latter weathering to a light 

 } 7 ellow, highly siliceous clay. 



The occurrence of Devonian strata in the central Missouri 

 region w r as known to Owen (1) in the early fifties, and he out- 

 lined its area with some degree of accuracy as follows : "In 

 Missouri this formation (Devonian) was traced, reappearing 

 for a very limited space in the valley of the Auxvasses in 

 Calloway county; skirting for a short distance one of the south- 

 ern promontories of the Iowa and Missouri coal-field, in close 

 proximity to the great uplift of magnesian limestone, of Silu- 

 rian date, in the same vicinity. It has, probably, a consider- 

 ably greater range in this locality than here ascertained and 

 laid down by me." 



Numerous exposures of the strata here considered occur in 

 Warren, Montgomery, Callaway, Boone, Cole, Moniteau and 

 Cooper counties, with their maximum development in central 

 Callaway county. While the Devonian of this region is readily 

 separable into two divisions upon both faunal and lithologic 

 grounds, the lower member only bears a distinctive name, and 

 this even is ill-defined as it appears in the literature. 



C. R. Keyes (2), in a discussion of the geological formations 

 of Missouri, defines the Callaway limestone or lower member 

 in the following manner : "In southeastern Missouri, rocks 

 containing the typical fauna of the Western Hamilton are 

 sparingly represented in Perry and Cape Girardeau counties, 

 in connection with the limestones above mentioned (Grand 

 Tower limestone). In this region the limestones belonging to 

 this group are dark colored shaly rocks, quite different from 

 the associated strata. 



"JSTorth of the Ozark uplift the Devonian rocks referred to 

 the Hamilton extend westward along the Missouri river as far 

 as Jefferson City, having their most typical development in 

 Callaway county. In several places abundant fossils of this 

 formation have been obtained from strata having lithological 

 characters not very unlike the beds of the eastern Ozark region 

 referred to the same age." 



The two paragraphs above quoted are somewhat misleading, 

 since if the writer means to apply the name Callaway lime- 





