8. Observations on Modern Glacial Action in Canada. By the Rev. W. Bleasdell, M.A.
(Communicated by Principal Dawson, F.E.S., F.Gr.S.)
Sir Charles Lyell, in his ' Principles of Geology,' has drawn attention to the effects of glacial action in Canada in the transportation of large stones and boulders on the shores of the river St. Lawrence to new positions by the powerful agency there exercised, more or less, every winter. As this subject possesses much geological importance, I write down a few observations of this kind that may be of interest.
There can be no doubt that in every portion of the province where large rivers, streams, and lakes abound, the effects of ice may be seen in the removal of gravel, stones, and shingle from sites where they have remained since the Boulder-drift period.
On that arm of Lake Ontario which commences at the outlet of the river Trent, at Trenton, and runs in a zig-zag direction for nearly 90 miles until it meets the main lake near Kingston, named the Bay of Quinte, the waters are frozen over every winter to a thickness of from 1-1/2 to 2-1/2 feet. Near the head of the bay (with which, from a residence of nearly twenty years, I am more especially conversant), and at some period during the season, a crack occurs right across from shore to shore. If this strikes a gravelly shore at either end (as it frequently does), the ice forming the crack being lifted up on each side, gravel, shingle, or stones may be seen imbedded in the ice which has thus been lifted up. These have been taken from the shallows by the ice coming into contact with them. This shows the effect of such ice on a shallow gravelly shore where the water is not more than from 1 to 2 feet deep. And hence it may be concluded that, not only from such shores, but also from muddy ones, earth, sedge, and other matters are transported to new localities at the breaking up of the ice in the spring, when the waters rise by the melting of the snows ; and thus we have a present geological agent acting powerfully every season in the removal of gravel, stones, boulders, and earthy matter to distant spots.
In the rapids of the rivers in Canada loose cakes of ice, named flood-, anchor-, or pack ice are formed ; and in the river Trent these, being formed thus a short distance above the deep water of that river's mouth, either pile up in a high mass on the solid ice below, or find their way under it, and, floating down to the bar near the mouth in the bay, there eventually dam up the waters more or less, and occasionally flood the banks. A large flood of this kind inundated the lower streets of the village of Trenton in January 1867 ; and the water freezing forthwith, there was a layer or stratum of ice of over a foot in thickness there for the rest of the winter. A flood of this extent is of unfrequent occurrence, however, and the ice barrier generally gives way before the waters rise to this level. From a similar cause the lower part of the city of Montreal was flooded by an accumulation of anchor-ice from the
