12 



ILLINOIS STATE GEOLOGICAL SURVEY 



Fig. 7.— Walches Cut, locality 6. Illinois Central 

 Railroad cut about 1.9 miles E-NE of Scotts- 

 burg. Section illustrated begins about 50 yards 

 east of overpass bridge. Carter coordinates 

 23-H-21, 4000 feet N. of S. line, 1035 feet E. of 

 W. line of quadrangle H-21, Princeton East 

 quadrangle, Caldwell County, Kentucky. 



oniodus erectus, appear to be restricted to 

 the lower Chester. Representatives of the 

 genera PoJygnatliiis and Synprioniodina 

 are also restricted to pre-Glen Dean rocks 

 in the type Chester area but must be eval- 

 uated further. 



Six species have been recorded from only 

 the Glen Dean. Three, Kladognathus mehli, 

 Lonchodina fumishi and Roimdya costata, 

 are uncommon; but the remaining three, 

 Hihhardella ortha, Larnbdagnathus fragili- 

 dens, and Lonchodina poracJaviger, are 

 sufficiently abundant to appear stratigraph- 

 ically significant. 



Uniformity of the Glen Dean Fauna 



The over-all uniformity of the conodont 

 fauna is impressive from three standpoints: 

 first, uniformity in differing lithologies; 

 second, uniformity between the lower and 

 upper parts of the formation; and third, 

 geographic uniformity. One important ex- 

 ception to this pattern will be noted later 



No differences were found in the species 

 represented in collections from differing 

 types of limestone — oolitic, crinoidal, dolo- 

 mitic, and others — nor between various 

 kinds of shale. Conodonts were found to 

 be more abundant and better preserved in 



LOG. 6 -WALCHES CUT 



Sandstone, tan, massive. 31' 



Covered interval. 8' 



Limestone, gray, thin-bedded, ^ 

 sandy, abundantly fossiliferous. 

 2'6" 



Stiale, dark gray, calcareous, with 

 limestone beds, fossiliferous. 9' 



Sandstone, gray, calcareous, \ 

 fossiliferous. I'-Z' 



Shale, dark gray 5' 



Sandstone, gray, thin-bedded 

 upper part calcareous, 

 very fossiliferous; middle 

 shale 5'6" 



Shale, very dark gray, 

 slightly fossiferous; 

 thin siltstone partings 

 37' 



Limestone, gray, 

 massive, medium to 

 coarse-grained. iQi^i" 



Shale, dark gray. 7 



CO 



o 



EXPLANATION OF PLATE 1 

 All figures X 40 



Numbers in parentheses after explanations refer to locality and sample numbers, for example 



(7-4) refers to locality 7, sample 4. 



Figure 



1, 2 Gnathodus modocensis Rexroad; 1, outer lateral view (7-4); 2, oral view (7-14), 



3-5 Gnathodus} sp.; 3, inner lateral view (8-7); 4, 5, oral views (8-2 and 8-7). 



6-11 Cavusgnathus unicornis Youngquist and Miller; 6, 7, inner and outer lateral views of 



mature specimens (1-43 and 9-30); 8, 9, oral and inner lateral views of young speci- 

 mens (both 2-6); 10, 11, oral and inner lateral views of an old specimen (1-26). 



12-14 Cavusgnathus convexa Rexroad; 12, inner lateral view of mature specimen (1-43); 



13, inner lateral view of old specimen (1-61); 14, outer lateral view of mature speci- 

 men (1-47). 



15-17 Cavusgnathus cristata Branson and Mehl; 15, inner lateral view (11-18); 16, aboral 



view (3-2); 17, outer lateral view (9-14). 



