PRE-CAMBRIAN ROCKS OF NEWFOUNDLAND 455 



schists (Buddington, 19 16). Yet the granite, granodiorite, and 

 many of the volcanics show little or no affects of metamorphism and 

 are quite unaltered. 



Whereas metamorphism has been a moderate factor, however, 

 faulting on a tremendous scale and often of remarkable intensity 

 has been the predominating feature of the diastrophic processes. 

 These faults trend in the main a little east of north, and the throw 

 along many of them is measurable in thousands of feet. A few of 

 the more important ones are the fault between the Cambrian and 

 pre-Cambrian along the east side of Conception Bay from Topsail 

 to Cape St. Francis, with a throw of 8,000 feet, as determined by 

 van Ingen; the fault a short distance inland from the west side of 

 Colliers Bay" in Conception Bay, which may be traced for almost ten 

 miles and separates the Cambrian from the pre-Cambrian and the 

 Conception slates from the volcanic series; and lastly, the fault on 

 the west side of Random Sound, which may be traced for fifteen 

 miles and brings Cambrian beds against pre-Cambrian granite and 

 the Conception slate series. 



UNCONFORMITY BETWEEN CAMBRIAN AND LATER PRE-CAMBRIAN 



The uncomformable relations of the Lower Cambrian beds to 

 those of the later pre-Cambrian, with the possible exception of the 

 Random formation, can be definitely established. At eleven widely 

 separated localities in Conception Bay the actual unconformable 

 plane of contact between the Lower Cambrian and the later pre- 

 Cambrian may be observed. 



At Brigus the Lower Cambrian rests with an angular uncon- 

 formity on the upturned beveled edges of members of the Avondale 

 volcanic series. Along Colliers Bay the Lower Cambrian with a 

 gentle dip rests unconformably on more or less vertical basalt flows 

 and breccias of the Avondale volcanic series. At Chapel Cove the 

 Lower Cambrian beds rest on the eroded surface of a quartz syenite 

 and contain pebbles of the underlying rock. At Duft's Station the 

 Lower Cambrian overlies granite, occupying hollows and filling 

 deep, narrow wedgelike spaces between joint planes so as to resemb.le 

 a network of veins on the surface. At Upper Gullies it rests with 

 unconformable relations on a gabbro mass. On Kelligrews Brook 



