H. H. Howorth—Traces of a Great Post-Glacial Flood. 118 
the relative levels of sea and land must be taken into account in 
explaining the distribution of marine clays and sands, boulder 
deposits, ete., which are often regarded with reference to the present 
levels of the country, or as contemporaneous deposits without regard 
to their elevation, a method certain to lead to inaccurate conclusions. 
The Saxicava Sand (/f) indicates shallow-water conditions with 
much driftage of boulders, and probably glaciers on the mountains. 
It constitutes in many districts a second boulder formation, and pos- 
sibly implies a somewhat more severe or at least more extreme 
climate than that of the Upper Leda Clay. ‘Terraces along the 
coast mark the successive stages of elevation of the land in and 
after this period. There is also evidence of a greater elevation of 
the land succeeding the time of the Saxicava Sand, and preceding 
the modern era.' 
It is well known that very diverse theoretical views exist among 
geologists as to the origin of the deposits above referred to. The 
conclusions which have been forced upon the writer by detailed 
studies extending over the last forty years, are that in Canada the 
condition of most extreme glaciation was one of partial submergence, 
in which the valleys were occupied by a sea laden with heavy field 
ice continuing throughout the summer, while the hills remaining 
above water were occupied with glaciers, and that these conditions 
varied in their distribution with the varying levels of the land, 
giving rise to great local diversities, as well as to changes of climate. 
There seems to be within the limits of Canada no good evidence of 
a general covering of the land with a thick mantle of ice, though 
there must at certain periods have been very extensive glaciers on 
the Laurentian axis and in the mountainous regions of the west.’ 
It does not, indeed, seem possible that, under any conceivable meteor- 
ological conditions, an area so extensive as that of Canada, if exist- 
ing as a land surface, should receive, except on its oceanic margins, 
a sufficient amount of precipitation to produce a continental glacier. 
Details on some of the above-mentioned formations will be found 
in my “ Notes on the Post-Pliocene of Canada,” and a large amount 
of recent information exists in the Reports of the Geological Surveys 
of Canada, and in papers published in the Canadian Naturalist and 
Geologist. 
V.—Traces or Aa Great Post-Gractat FxLoop. 
do. Evipence or tHE Marine Drirt. 
By Henry H. Howorrn, F.S.A. 
(Concluded from page 78.) 
HESE difficulties are assuredly most embarrassing for those who 
conclude that the shell-beds point to the positions where they 
are found having once been the sea-bottom, and especially for those 
who argue that its submergence and re-emergence were the result 
of causes operating for thousands of years. We must remember 
1 Supplement to Acadian Geology, 3rd edition, pp. 14, et seq. 
2 G. M. Dawson, Reports on British Columbia, and Superficial Geology of British 
Columbia, Journal Geol. Society, 1878. 
DECADE II.—vVOL. X.—NO. III. 8 
