BY \V. N. BENSON. 577 



The chief point of interest, in these rocks, is the abundance of 

 the spilites. Their chief occurrences are shown on the map, but 

 it should be noted that, as the nature of this rock and its peculiar 

 interest were unknown to the author when the field-work was in 

 progress (1909-10), less attention was paid to it than would 

 otherwise have been the case. With this must be considered the 

 very complex relation between the dolerites and the spilites, 

 which adds further uncertainty to some of the observations. The 

 occurrences mapped, however, have all been proved, by micro- 

 scopic work, to be true spilite. North of Bowling Alley Point, 

 the spilites are rare, but south of the township, a flow commences, 

 which may be traced, with interruptions, right to the limit of 

 the map. Commencing near the Peel River, it passes across the 

 face of the hillside and forms the high point known as Tom 

 Tiger, overlooking the mouth of Swamp Creek. Beyond, it runs 

 across the face of Frenchman's Spur, where it is very fresh, and, 

 after a break, widens out into the mass which forms the hill west 

 of the Devil's Elbow, on the Hanging Rock Road. From here, 

 it splits into two or more bands, one of which continues south- 

 wards to the head of Oakenville Creek, where it passes below 

 the basalts, forming a ridge protruding into their lower portion. 

 The splitting into several bands is probably the result of strike- 

 faulting. 



North of Tom Tiger, the mass is much disturbed with dolerite- 

 intrusions, and veins of axinite with epidote-quartz and calcite, 

 producing a rock closely resembling that described by Lacroix 

 from Pic d'Arbizon, in the Pyrenees(28). This latter, he con- 

 siders produced by the last stages of activity of an intrusive 

 granite. It is difficult to see how this applies here. Unfor- 

 tunately the occurrence was not thoroughly investigated in the 

 field or laboratory. The axinite has been described, mineralogi- 

 cally, by Dr. Anderson(29). 



A second and lower flow of spilite is that which forms the 

 high, shutter-like wall in front of the Swamp Creek Falls, which 

 have just broken through (Plate xxiv.). This flow, also, may be 

 traced for some distance north and south. A third, possibly the 

 uppermost horizon, occurs on the western slopes of Tom Tiger, 



