132 A. F. BUDDINGTON 



of a fault zone. For at talc prospects 3, 4, and 5 the volcanics are 

 faulted against either granite or green slate beds, and at prospect 

 3 the granite adjacent to the fault plane is silicified and pyritized 

 and the rhyolite is silicified and carries traces of pyrophyllite. 

 The pyrophyllite veins in turn are offset by small cross-faults. 



CHARACTER OF VOLCANIC SERIES 



The volcanics comprise a thick series of rhyolite and basalt 

 flows with corresponding interbedded breccias, crystal tuffs, and 

 tuffs, and a minor amount of waterworn material. The evidence 

 with respect to their origin all points to their having accumulated 

 under subaerial conditions. 



TOPOGRAPHY 



The topography developed on the volcanics at Manuels is that 

 of a long, narrow, more or less barren plateau about 600 feet above 

 sea-level. The volcanics at the head of Conception Bay are carved 

 into a series of rugged isolated hills or ridges with differential eleva- 

 tions of from 200 to 1,000 feet. Glaciation during the Pleistocene 

 period had a marked effect on the superficial features of the country, 

 and many of the outcrops were scraped and polished by this agency. 



WALL ROCKS OF THE PYROPHYLLITE VEINS 



The pyrophyllite is confined almost exclusively to the rhyolite 

 flows. Occasionally, however, pockets are found in the rhyolite 

 breccias and conglomerates, but none at all occurs in any of the 

 other rocks. The rhyolite flows exhibit three characteristic struc- 

 tures: flow or banded, spherulitic, and elliptical or lenticular. 

 The spherulites may range in size from micro-spherulites visible 

 only with the high powers of the microscope to huge spheroids as 

 big as a man's head or even larger. They are usually more or less 

 replaced by quartz of chalcedony. The elliptical structure has 

 been called such because of its appearance on the weathered surface 

 of the rock, where it shows as an assemblage of rude ellipses, or 

 as lenses surrounded by a more or less schistose material which 

 may be pyrophyllitized (Fig. 2). The ellipses vary from several 

 inches to a foot in the direction of their longest axis. At talc 

 prospect 5 a rhyolite showing this structure also contains scattered 



