272 



They may, therefore, be younger than the granite and 

 possibly are of Cambrian age. 



The first rock cut to the west of the brook exposes 

 weathered and, in places, sheared igneous rocks. Two 

 main rock types are present, one is represented by dense 

 greenish black and reddish rocks apparently approaching 

 an andesite in composition. The other type is fine-grained, 

 greenish black in colour, and is of the composition of a 

 diabase. The diabase closely resembles the dykes of this 

 rock cutting the Pre-Cambrian granite in the first rock 

 cut and is thought to be the same rock. 



At the eastern end of the rock cut are a few exposures of 

 an andesite tuff, while at the west end, there is a small 

 exposure of conglomerate. Throughout the length of the 

 cut, the andesite and diabase alternate. The relations of 

 the diabase to the andesite are not known. The con- 

 glomerate at the west end of the rock cut, is penetrated by 

 the diabase and presumably the diabase also cuts the 

 andesite either in the form of dykes or sills. 



Approaching the west end of the rock cut, on the sea- 

 ward side, are exposures of reddish, shale-like rocks 

 probably representing much decomposed andesite. On 

 the south side, at the west end of the rock cut, is a small 

 exposure of conglomerate composed of somewhat angular 

 rock fragments of small size in a quartzite matrix. The 

 rock fragments closely resemble the andesites. This con- 

 glomerate and the diabase that cuts it, mark the end of 

 exposures of igneous rocks. The same igneous assemblage 

 occurs on the beach north of the railway and the exposures 

 there also terminate with an outcrop of conglomerate. 

 In the hill country to the southwest of the railway are 

 outcrops of the same igneous rocks as occur on the railway. 



The relations existing between the igneous rocks and 

 the succeeding Cambrian sediments is not directly known. 

 Both on the shore and along the railway, the exposures 

 of the two classes of rocks are separated by a concealed 

 interval. On the shore, the concealed interval is about 

 250 feet (76 m.) in width. Beyond it to the west are 

 continuous exposures of green and reddish grits, sandstones 

 and shales of Cambrian age. The sedimentary beds are 

 faulted and closely folded. It is assumed that they are 

 separated from the igneous rocks on the east by a fault. 

 The conglomerate at the west end of the rock cut possibly 

 represents the base of a series of rocks younger than the 



