900 STRATIGRAPHICAL GEOLOGY.  [Boox VI. 
water, discharged across the land, levelled down the heaps of detritus 
that had formed below or in the under part of the ice. ‘The lower por- 
tions of the Champlain series are, therefore, sometimes unstratified or 
very rudely stratified, while the upper parts are more or less perfectly 
stratified. Towards the eastern coasts, and along the valleys penetrating 
from the sea into the land, these stratified beds are of marine origin, and 
prove that during the Champlain period there was a depression of the 
eastern part of Canada and the United States beneath the sea, increasing 
in amount northwards from a few feet in the south of New England {to 
more than 500 feet in Labrador, The marine accumulations are well 
developed in eastern Canada, where they show the following sub- 
divisions : 
U St. Maurice and Sorel sands; Saxicava sand of Montreal; upper sand 
Mae { and gravel of Beauport ; upper Champlain clay and sand of Vermont. 
Tester Leda clay of the St. Lawrence and Ottawa; lower shell-sand of Beau- 
Wet.) port; lower Champlain clay of Vermont. 
The lower stage, chiefly clays, which rise to a height of 600 feet 
above the sea, includes some interstratified beds of siliceous sand, but 
few boulders. It contains marine organisms, such as Leda truncata, 
Saxicava rugosa, Tellina grenlandica, bones of seals, whales, &c. On the 
banks of the Ottawa, in Gloucester, the clays contain numerous nodules 
which have been formed round organic bodies, particularly the fish 
Mallotus villosus or capeling of the lower St. Lawrence. Dawson also 
obtained numerous remains of terrestrial marsh plants, grasses, carices, 
mosses, and alge. ‘This writer states that about 100 species of marine 
invertebrates have been obtained from the clays of the St. Lawrence 
valley. All except four or five species in the older part of the deposits 
are shells of the boreal or Arctic regions of the Atlantic; and about half 
are found also in the glacial clays of Britain. The great majority are 
now living in the Gulf of St. Lawrence and on neighbouring coasts, espe- 
cially off Labrador.’ 
Terraces of marine origin occur both on the coast and far inland. 
On the coast of Maine they appear at heights of 150 to 200 feet, round 
Lake Champlain at least as high as 300 feet, and at Montreal nearly 
500 feet above the present level of the sea. In the absence of organic 
remains, however, it is not always possible to distinguish between 
terraces of marine origin marking former sea-margins, and those left by 
the retirement of rivers and lakes. In the Bay of Fundy evidence has 
been cited by Dawson to prove subsidence, for he has observed there a 
submerged forest of pine and beech lying 25 feet below high-water 
mark, 
Inland the stratified parts of the Champlain series have been 
accumulated on the sides of rivers, and present in great perfection the 
terrace character already (p. 382) described. The successive plat- 
forms or terraces mark the diminution of the streams. They may be 
connected also with an intermittent uprise of the land, and are thus 
analogous to sea-terraces or raised beaches. Hach uplift that increased 
the declivity of the rivers would augment their rate of flow, and con- | 
sequently their scour, so that they would be unable to reach their old 
flood-plains. Such evidences of diminution are almost universal among 
' Dawson, Acadian Geology, p. 76. 
* Op. cit. p. 28. 
