50 



more of the formation and also a bed of volcanic ash occupy 

 the depression in which the creek flows. 



East of the creek are green schists of detrital origin 

 traversed by sheet-like masses of diabase and diorite, 

 which may be dykes or flows and which are younger than 

 the Steeprock series. With these intrusions there seems 

 to be associated diabase dykes which cut the granite and 

 greenstone in such a way that they apparently represent 

 the orifices through which the larger masses found their 

 way to their present position. 



Fossiliferous Limestone at Point No. 1. — By crossing 

 in an easterly direction to a steep brown bluff, the first 

 exposure of the limestone in the eastern limb of the syncline 

 may be examined. The contact with the older rocks is 

 not exposed here, but lies under the drift in the depression 

 just to the east. An example, on a small scale, of the 

 deformation which the formation once suffered, may be 

 seen at the western corner of the point. The original 

 bedding and joint-planes of the limestone are rendered 

 visible by the abundant development of lime-silicate 

 minerals along them, which have weathered into relief. 

 A small exposure of a calcareous green schist probably 

 developed from the limestone may be seen also at this point. 

 The attitude of the beds should be observed. 



The fossils are located chiefly at the southern corner of 

 the bluff, and are quite abundant, especially near the waters 

 edge. Atikokana lawsoni (15) seems to be the main 

 species represented at this point. It is one of a group of 

 organisims related to the sponges. Both silicated and 

 calcareous varieties occur. 



From Point I a southeasterly course is taken to Point No. 

 2, about half a mile (o • 8 km.) distant. Along the route bold 

 Laurentian hills easily distinguishable by their pale pink 

 weathering, may be seen to the east. Dark-coloured 

 patches occur scattered here and there through the gneiss. 

 In some cases there are dykes similar to those associated 

 with the crystalline traps of the Steeprock series, while in 

 other cases there are detached masses of the intruded 

 Keewatin engulfed by the granite when still in a viscous 

 condition. The Laurentian-Keewatin contact zone is 

 approximately in the trough occupied by the lake. A 

 narrow fringe of limestone which may be distinguished by 

 its brown colour, extends almost continuously along the 

 east shore between the two points. 



