Some Salient Points in the Science of the EarthDawson, John William, Sir
Science
Some Salient Points in the Science of the Earth
Dawson, John William, Sir
Geology; Paleontology
If we pass inland from the shore belt of boulders, we shall find
similar appearances on the inland terraces at various heights, up to
at least 400 feet. These are inland boulder belts belonging to old
shores now elevated. Like the modern boulder belt these inland belts
and patches consist partly of Laurentian rocks from the North Shore,
partly of sandstones and conglomerates in place near to their present
sites. In some places the stones are smaller than those of the present
beach, in other places of gigantic size. These boulders lie not only
on the bare rock striated in places with ice grooves pointing to the
north-north-east; but on the old till or boulder clay, which also
abounds with boulders, and which is more ancient than the superficial
boulder drift. Locally we find here and there masses of fossiliferous
limestone which must have been derived from the high ground to the
south of the St. Lawrence, and which have been borne northward either
by drift ice or by local glaciers.
If now we study the polished and scored surfaces of rocks in the St.
Lawrence valley and the bounding hills, we shall find that while the
former testify to a great movement of ice and boulders up the river
from the north-east, the latter show evident signs of the movement
of local glaciers down the valleys of the Laurentide hills to the
south, and on the continuation of the Appalachians south of the river
similar evidence of the movement of land ice to the north. Thus we
have evidence of the combined action of local glaciers and floating
ice. To add to all this, we can find on the flat tops of the hard
sandstone boulders on the beach the scratches made by the ice of last
winter, often in the same north-easterly direction with those of the
Pleistocene time.
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