37 



Athvris spiriferoides (Eaton ), all in a perfect state of preser- 

 vation. The same fossil occurs in the shale between the 

 concretions, and when thus found, it presents its original 

 gibbous character. Above or below this layer, however, 

 this fossil usually occurs in a compressed condition from the 

 settling down of the shale masses on lithifying, thus show- 

 ing well, how the presence of such concretions in a bed, may 

 protect the fossils from the compression incident upon the 

 lithification of the containing rock. This layer furnishes 

 most of the specimens of this brachiopod, which is nowhere 

 else so characteristic as at Eighteen Mile Creek. 



Section 7 (B). 



Plates XII and XIII. 



This section extends north-west from a point directly 

 north of the northern end of Section 6, to the bridge on 

 which the Lake Shore road crosses the creek. It is cut into 

 the right bank of the stream, and has a total length of 

 about twelve hundred feet. Near the middle of the section a 

 small lateral stream has cut a V-shaped gully down to the 

 Styliolina limestone, over which the water falls in wet 

 weather. Below this is a larger V-shaped recession, a 

 diminutive "corrv," which here marks the beginning of a 

 lateral gorge. (Plate X.). 



The lower portion of the section is covered by a talus of 

 fine shale particles, derived from both Moscow and Hamil- 

 ton beds. At the foot of the cliff are large fragments of 

 limestone and shale, with fossils, as well as a debris of 

 foreign material. The difference in the steepness of the 

 bank, between this section and the preceding one, forms an 

 interesting study, the small amount of undercutting in 

 Section 7 being due, as already noted, to the shallowness 

 and width of the stream, which two features combine to 

 dissipate the force of the current, and also to the presence 

 of the large rocks at the foot of the cliff, which act as a 

 barrier to the inroads of the current. 



