THE BAY OF FUNDY TIDES AND MARSHES. 253 



cms period, the bay was nrach wider and somewhat longer than it 

 is now. The long ridge of trap rock, known as the North Moun- 

 tain, which stretches as a huge wall between the Annapolis Val- 

 ley along its southern, and the waters of the bay along its north- 

 ern base, did not then exist, and the waters of the bay extended 

 uninterruptedly over the whole of the Annapolis Valley to the 

 base of the Silurian hills which, under the name of the South 

 Mountain, now form the southern inclosure of the valley. East- 

 wardly the head waters of the ancient bay washed the Devonian 

 and Carboniferous rocks of the Cobequid Hills, while the north- 

 ern shore line of the present bay, skirting the southern limit of 

 the Palaeozoic rocks of New Brunswick, is substantially identical 

 with that of the original bay. 



In general character the tidal movements of this larger Atlan- 

 tic inlet were the same as in the smaller modern bay. And the 

 semidaily ebb and flow of the waters produced, by their incessant 

 attrition with the carboniferous limestones, shales, and sand- 

 stones, and the other ancient rocks that formed the bed and mar- 

 gins of the bay, immense quantities of sand and mud — sediment 

 that was redistributed over the greater part of the Fundy Valley. 

 Subsequent changes of level caused a recession of the waters to 

 within their present limits, and brought to view, as the Triassic, 

 or new red sandstone, extensive areas of these deposits. These 

 red sandstone strata are still to be seen in shreds and patches at 

 various points in the Annapolis Valley and on the shores of the 

 Minas and Annapolis Basins. Their general dip toward the 

 north indicates that the epoch-closing movement which nar- 

 rowed the Bay of Fundy within its present confines was a sinking 

 of the bed along its northern or New Brunswick border. 



Following this subsidence, and as the concluding events in the 

 series of seismic convulsions by which the region gained its pres- 

 ent topographical features, occurred the volcanic eruptions in 

 which the North Mountain had its origin. This long, trappean 

 wall forms the southern boundary of the bay from Cape Split to 

 the extremity of Digby Neck, a distance of one hundred and 

 twenty-five miles, the only interruption to its continuity being 

 the singular gap called Digby Gut, which gives an entrance into 

 the beautiful Annapolis Basin. Though there were probably 

 many volcanic vents along this extended line of fracture, yet the 

 scene of greatest activity was undoubtedly near Cape Split, at the 

 entrance to Minas Basin, scattered along the shores of which on 

 either side are isolated patches of amygdaloidal trap. Transverse 

 ridges of the same volcanic rock run at intervals, also, across the 

 bottom of the bay. 



It is the grinding action of the Fundy waters upon these two 

 Triassic rocks, the trap and its underlying sandstone, that provides 



