Acadian and St. Lawrence Water-shed. 411 
that over the intervening seas were in process of accumu- 
lation a vast thickness of sedimentary beds, pebble, sand, 
mud and lime-beds, spread horizontally over the sea-floor, 
and receiving from time to time the more durable relics of 
the life-—Brachiopods, Crinoids, Graptolites, &c.,—with 
which those seas were filled. Another period of upheaval 
then ensued, and, through pressure brought to bear upon 
the same sea-floor, portions of its surface became crumpled 
up into folds and ridges, and its materials more or less 
altered in character. At the same time, along the south 
side of the St. Lawrence, where the foldings are most 
numerous and excessive, the ridges thus produced were 
thrust above the sea level, thus defining that great estuary 
upon the southern as well as on the northern side, and em- 
bracing the system of heights (the Notre Dame Mts., &c.) 
already described as extending through the Gaspé peninsula 
and forming the great divide between the St. Lawrence 
and the Bay Chaleur. Along the southern side of the 
Lower Silurian rocks thus folded, we have seen that the 
Upper Silurian rocks meet them unconformably, and from 
their northern edge, in some places not more than nine 
miles from the shores of the St. Lawrence, spread south- 
ward to the Bay Chaleurs and upper St. John, as well as 
farther, over all the northern portions of New Brunswick 
and Maine. From the absence, or slight representation, 
through most of the Gaspé peninsula, of the inferior 
portions of the system (Niagara group) we may infer that, 
for some time after the opening of the Silurian era, this 
district still remained too elevated to be reached by oceanic 
waters: but the occurrence of limestones of this age at 
_ Cape Gaspé, as well as on Anticosti, filled with marine 
organisms, shows that in these localities at least the great 
St. Lawrence Gulf was still in existence. At the same 
time, the occurrence of the heavy beds of conglomerate, 
fully 1000 feet in thickness, with the succeeding shales and 
sandstones, carrying Niagara fossils, on Lake Temiscouata, 
would seem to indicate that these waters of the Gulf spread 
westward, at least as far as that point, though of diminished 
