38i 



Middle Cambrian; — 



b. Greenish and dark shales and fine sandstones 



a. Light grey, quartzitic sandstone 40-45 feet (12-14 m.) 



Lower (?) Cambrian (Etcheminian) ; — 



c. Reddish-purple and greenish shales 



and thin sandstones 52 feet (15-8 m.) 



b. Concealed (presumably shales and 

 sandstones) 85 feet (26 m.) 



a. Dark reddish conglomerates, sand- 

 stone and shale 12 feet (3-6 m.) 



Pre-Cambrian . — 



The lowermost beds of the Etcheminian and the nature 

 of the contact with the Coldbrookian (Pre-Cambrian) is 

 indicated in a series of exposures along the branch road 

 leading to the northeast. This road passes along the 

 south side of a low rocky ridge of the dark green, fine- 

 grained trachyte immediately underlying the Cambrian 

 beds. The Pre-Cambrian volcanic rock in some of the 

 exposures on the road side is reddish in colour and in places 

 possesses an irregular, shale-like parting, apparently re- 

 sulting from weathering. At some points, the igneous 

 rock is less altered and is of a pale greenish colour. At 

 several places are small exposures of fine greyish or slightly 

 reddish conglomerate overlying decomposed trachyte 

 and evidently mainly composed of detritus from the Pre- 

 Cambrian volcanic. 



The purple weathering, green volcanic rocks underlying 

 the Cambrian forms a band striking to the northeast. 

 This band where it is traversed by a path running northward 

 to Mount Pleasant avenue is about 700 feet (215 m.) wide. 

 Along the pathway outcrops are few but the rocks are well 

 exposed on the ridges rising on both sides. The igneous 

 rock in most places is quite uniform in appearance being 

 a fine grained, almost dense trachyte with minute feldspar 

 phenocrysts. In some places as along Mount Pleasant 

 avenue where it skirts the shores of Lily lake, the rock 

 has a fragmental structure and appears to be of tuffaceous 

 origin. The occurrence of this fragmental variety suggests 

 that the igneous rock as a whole is of effusive origin. 

 The age of the rock is supposedly Pre-Cambrian since it 



