454 A. F. BUDDINGTON 



GENERAL GEOLOGY 



The later pre-Cambrian beds have undergone at least two 

 periods of folding, one at the close of the later pre-Cambrian, 

 possibly the Penokean revolution, as defined by Blackwelder 

 (1914), the other the Taconic. As a consequence of this, and of 

 probable later movements, the beds are much disturbed, more or 

 less closely folded, and very considerably faulted. The core of a 

 major anticline composed of complexly faulted and folded beds of 

 the volcanic series, cut across at a small angle by a stock of grano- 

 diorite, is exposed at the head of Conception Bay. At Chapel Cove 

 its eroded surface is overlain by beds constituting the south end of a 

 northward-pitching synclinal fault block of Cambrian sediments, in 

 which Conception Bay is excavated. We have here apparently the 

 phenomenon of the location of a younger syncline in sediments 

 deposited in a basin on the eroded crest of an anticline. 



Cutting across the east flank of the anticline is a batholith of 

 granite forming the backbone of the St. John's Peninsula and called 

 by the writer the Holyrood granite batholith. This is bordered on 

 the east by a narrow band of the volcanics overlain by successively 

 higher beds involved in minor folds until the trough of a major 

 syncline in the Signal Hill series is reached east of St. John's. 

 According to Murray and Howley's map of 1881 the Carbonear 

 Peninsula is formed of later pre-Cambrian beds which overlie the 

 volcanics and are involved in two major synclines in the troughs of 

 which the Signal Hill series appears, with an intervening anticline 

 on the core of which the Torbay series appears. The Placentia 

 Peninsula, according to the same map, is composed of a syncline of 

 beds in the trough of which the Signal Hill series lies, while the 

 volcanic series forms its western border and appears on the flank 

 of an anticline. 



Metamorphism, although not extreme, has yet affected the rocks 

 to a considerable degree. The beds lie in folds which, although 

 probably not closed, yet approach that state, and a slaty cleavage 

 at an angle to the bedding is prevalent throughout the entire bedded 

 series. Along localized zones basaltic flows and breccias have been 

 changed to chloritic schists, and rhyolite flows have been 

 analogously altered to pinite, quartz-pyrophyllite, or pyrophyllite^ 



