466' A. F. BUDDINGTON 



The predominance and widespread distribution of the red and 

 brown volcanic tuffs and breccias, which owe their color to satura- 

 tion and cementation with hematite, point toward subaerial 

 exposure rather than toward local effects of volcanic gases. 



The constant association of volcanic conglomerates or sandstone 

 with the breccias, tuffs, and flows indicates the work either of river 

 erosion, or wave work, or both. The first seems more probable in 

 view of the constant recurrence of conglomerate beds in the strati- 

 graphic succession, as well as the fact that beds of conglomerate 

 150 to 200 feet, thick with well-rounded bowlders up to three feet 

 in diameter, are exceptional within marine deposits, even within 

 marine volcanic deposits. On the other hand such conglomerates 

 are commonly found associated with subaerial volcanics of all ages. 

 Those of Newfoundland are such as might be expected to form along 

 river valleys draining a region of great active volcanic cones such as 

 this probably was. Although some of the conglomerates may have 

 been deposited in standing water, the indications are that for the 

 most part they were deposited on a land surface during quiescent 

 periods between successive volcanic outbursts which repeatedly 

 buried them with the products resulting from extravasation and 

 explosion. 



The volcanics are, so far as known, the oldest formation of the 

 later pre-Cambrian in this district. They are intruded by granite, 

 and together with the granite are overlain unconformably by Lower 

 Cambrian sediments. The pre-Cambrian volcanics of the Blue 

 Ridge of Virginia and Maryland present similar relationships 

 (Keith, 1892), and in the present state of knowledge it seems prob- 

 able that in early later pre-Cambrian times a chain of volcanic cones 

 extended from Newfoundland to North Carolina and farther, in a 

 zone more or less parallel to the present coast line. 



CONCEPTION SLATE SERIES 



The Conception slate series was examined by the writer along 

 the east side of Conception' Bay from Portugal Cove to Topsail; 

 along the west side. Colliers Bay north to Brigus; near La Manche 

 on the Isthmus of Avalon; and along Smith and Random sounds on 

 Trinity Bay. Owing to folding, faulting, and covered exposures 



