256 SIDNEY POWERS 



FAULTS 



The disturbance at the close of the Newark sedimentation threw 

 the rocks of this group into fault-blocks with a monoclinal tilting 

 toward the northwest. With such a structure, the major faults 

 would tend to assume a northeast-southwest trend, and some of the 

 more important faults should bound the formation on the north 

 ami northwest. 



The faults at the margin of the Triassic area are confined to 

 the northern and western sides. Thus the basalts of Grand Manan 

 are faulted down on the west side, while the pre-Triassic rocks on 

 the east side of the island are probably tilted up. The older forma- 

 tions against which the basalts were downthrown have since been 

 eroded away, because they were less resistant than the basalts, and 

 Grand Manan Channel has been formed in them. 



The northern and northwestern sides of the Triassic areas at 

 Split Rock, Quaco, Martin Head, and Waterside are all dropped 

 down as fault-blocks against older rocks. At Martin Head the 

 pre-Cambrian rocks form Martin Head itself, which is south of 

 the exposure of the Triassic sediments. This exposure of older 

 strata may be explained either as a horst or as the basement upon 

 which the southern limb of the Triassic syncline rests. The latter 

 view is favored, making the Triassic and the exposure of pre- 

 Cambrian part of one fault-block, with a fault south of the pre- 

 Cambrian. There also appears to be a minor fault in the axis of 

 the Martin Head syncline. 



The fault of greatest displacement in the Fundy region is the 

 Cobequid fault (shown on the general map of the region), which 

 stretches from West Advocate, north of Cape d'Or, to a point 

 northeast of Truro, a distance of 90 miles. On the north side of the 

 fault is the Cobequid group of sedimentary and igneous rocks which 

 composes the Cobequid Mountains. On the south side of the fault 

 are Triassic sandstones at W T est Advocate and Advocate Harbour, 

 and Pennsylvanian rocks east of Advocate Harbour. The displace- 

 ment of this fault is probably 2,000-3,000 feet. 



South of the Cobequid fault is another east-west fault which 

 bounds the Triassic on the north from Cape Sharp to the Chiganois 

 River (northeast of Truro) . The displacement of this fault appears 



