470 A. F. BUDDINGTON 



SIGNAL HILL SERIES 



As near as can be judged from the descriptions of Murray and 

 Howley (1881) and from the experience of the writer the Signal Hill 

 series outcrops mainly in the troughs of synclines or synclinoria 

 over an area extending for a length of about 200 miles in a north- 

 northeast-south-southwest direction and about 75 miles at right 

 angles to this. 



The series consists of a very thick succession of reddish-brown, 

 occasionally green, feldspathic sandstones and conglomerates, with 

 intercalated shale beds and about 1,300 feet of greenish-gray, thick- 

 bedded feldspathic sandstones at the base, giving a thickness 

 estimated at about 10,000 feet. Murray's estimate of 3,120 feet 

 for this series referred only to the beds on the west side of St. John's 

 harbor, which constitute but a part of the series. 



Thon-gallen or intraformational conglomerate beds are abun- 

 dant. The majority of the conglomerate beds may be appropriately 

 described as gravel or pebble beds, with the pebbles varying in size 

 from one-fourth of an inch to an inch in diameter, and prevailingly 

 subangular to rounded. 



Because of the predominating sandy character of such a 

 thick series of sediments; the repetition and often considerable 

 thicknesses of conglomerate beds; the presence of so much fresh 

 plagioclase and orthoclase throughout the rocks; the prevailing 

 subangular character of the component grains; the predominating 

 red color due to interstitial hematitic mud, to films of hematite, 

 and to oxidized grains of basalt, rhyolite, and magnetite; the 

 constant recurrence of thon-gallen beds; frequent cross-bedding; 

 lithologic alternations of sandstone, conglomerate, and shale; and 

 the absence of any limestone, fossils, or carbonaceous materials, the 

 writer has been led to conclude that these beds originated as domi- 

 nantly fluviatile deposits of subaerial origin in a subarid cHmate. 

 It is quite possible that the basal 1,300 feet of green-gray sand- 

 stones accumulated under a permanent water-level; but if so the 

 water was apparently drawn off or excluded at the time of accumu- 

 lation of the succeeding reddish-brown series. 



In thin sections from specimens of deep, livid-brown sandstone 

 from Signal Hill the rock is found to consist of angular to subangular 



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