38 THE DEVONIAN OF MISSOURI. 



shale; but close as it is, it does not warrant the reference of the 

 formation to one of the Iowa formations. No rocks between 

 Callaway County and the outcrops of the Lime Creek and Cedar 

 Valley of Iowa are of the same age as the Snyder Creek and the 

 gap is too large to bridge with present evidence. 



The best outcrops of Snyder Creek shale are in Callaway 

 County, but even in this region of best development the forma- 

 tion is absent over considerable areas. Its westernmost outcrops 

 are near the Fulton branch of the Alton Railroad near New 

 Bloomfield where the section is as follows. 



Section along the road 1| mileseast of New Bloomfield: 



Feet. Inches. 



Burlington 



Brown limestone capped with weathered limestone. 



Unconformity 



Sylamore sandstone 



Blue and yellow shale 9 



Green sandstone 6 



Unconformity 



Snyder Creek shale 



1. White to buff, very fine-grained sandstone, in beds up to 8 inches 



thick which alternate with beds one to two inches thick of 



white sandy shale 5 



2. Brown to bluish-brown sandy shale which weathers to yellowish 



brown. Some limestone nodules. Shale not in thin layers. 

 Exposure too imperfect for accurate description 15 



3. Nodular limestone interbedded with shale. All light gray weather- 



ing to light yellow. Stromatopora solidula Hall and Whitfield, 

 Athyris fultonensis (Swallow), Atrypa reticularis (Linnaeus), 

 Spirifer annac Swallow, Cyrtina triquetra Hall, Stropheodonta 

 demissa (Conrad), Stropheodonta boonensis Swallow, Zaphrentis 

 sp., Paracyclas elliptica Hall and Pleurotomaria isaacsi Hall 

 and Whitfield are common fossils 15 



Total Snyder Creek 35 



Callaway limestone 



Dark-blue limestone 1 



Yellowish gray shaly limestone 12 



Snyder Creek shale at the type locality on Craghead Creek 

 in SWM Sec. 17, T. 46 N., R. 9 W., six miles south of Fulton, 

 Callaway County. The details were worked out by James S. 

 Williams. 



Feet. Inches. 



Burlington limestone, gray crystalline limestone, which weathers to brown 

 sandy texture, containing many crinoid stems, overlaid by brown 

 sandy phase of Burlington ■. 1 2 



Sylamore sandstone: 



Greenish-brown friable sandstone 6 



Hard dense light-gray to pink sandstone 3 J^ 



Snyder Creek shale: 



1. Yellowish-brown sandy shale, very light where not weathered. . . 3 3 



2. Drab to blue dense limy shale with several thin beds of shaly 



" limestone, in part sandy, containing many large, coarsely 

 plicated Atrypa reticularis (Linnaeus) 5 2 



3. Covered 1. 8 



4. Blue to drab limy shale, somewhat sandy near top, containing 



several species of Stropheodonta in abundance 1 2 



