40 



which occurs throughout the lower shales. In this bed, 

 however, it occurs in great abundance, almost to the 

 exclusion of every other form. The bed is not well exposed 

 in this section owing to the talus, but in the east branch of 

 Idlewood Ravine, which mouths in the main gorge below 

 the bridge, it appears both in the bed and banks of the 

 ravine. 



Section 8 (A). 



Platp; XIV. 



This is the lowest section in the gorge, occurring in the 

 left bank and extending from near the mouth of the creek 

 halfway- to the bridge. Its total length is not over one 

 thousand feet, and it extends north forty degrees west, by 

 south fortv degrees east. Its height is about fifty-six feet 

 above the normal lake level. 



Only middle Devonian strata are exposed in this section, 

 the Moscow shales forming the top member. The greater 

 portion of these are exposed near the upper end of the 

 section, but owing to the rise of the strata north-westward, 

 only a few feet occur at the lower end of the section. The 

 Encrinal limestone occurs throughout, and large blocks of it 

 are found at the foot of the section. The lowest bed exposed 

 at the upper end of the section is an argillaceous limestone, 

 which in places becomes shaly, and the total thickness of 

 which is about a foot. This contains very few fossils, 

 Spirifer niucronatiis (Conrad) and a few pelecypods being 

 the only ones observed. Underlying it are about six feet of 

 shale, which become exposed at the lower end of the section. 

 These contain few fossils, principally Spirifer wucronatus 

 (Conrad) and Phacops rana (Green). Below them, and 

 exposed only near the lower end of the section are the 

 "Trilobite beds." These are three in number. The upper 

 one is a foot thick, shah' and often fissile, 3'et sufficiently 

 calcareous to be distinct from the overlying shale. It is very 

 rich in trilobites, though usually the heads and tails alone 



