268 SIDNEY POWERS 



and of plant and animal remains, all favor long oxidation of the 

 sediments in a dry tropical climate. 



The Scots Bay formation was deposited in part, at least, in a 

 lake, because fish remains occur in the strata. This lake came 

 into existence soon after the extrusion of the North Mountain 

 basal flows, as is indicated by the lack of erosion in the upper 

 amygdaloid. 



The Five Islands volcanics are interpreted as representing a 

 phase of igneous activity slightly earlier than that in which the 

 North Mountain basalt flows were extruded. The volcanics may 

 have come from central vents as well as from fissure eruptions. 



The North Mountain basalt must have come from fissure 

 eruptions, and spread out over a large portion of the Triassic 

 geosyncline, as is indicated by the widely separated areas at 

 North Mountain and at Grand Manan. The geographical extent 

 of any individual flow is impossible to determine, but it appears 

 that the earliest flow, or series of flows, was the thickest. 



The physiographic conditions accompanying the formation 

 of the Five Islands volcanics and the North Mountain basalts 

 are poorly shown. The base of the North Mountain basalt is 

 exposed only on Grand Manan, and there it is greatly weathered. 

 No evidence of contemporaneous lakes over which the lava 

 flowed has been found. 



