-Teasons: 
J. W. Dawson on the Drift. - 233 
earth has, like most other kinds of progress, been not by a con- 
tinuous evolution, but by a series of cycles, of great summers 
and winters, or days and nights of physical and vital change, in 
each of which all things seem to revolve back to the place of 
beginning, only to begin a new eycle, or new turn of a spiral, 
similar to the last in its general course, though altogether differ 
ent In its details, accompaniments and results. 
On the Boulder Drift of Canada, 
There is another subject of great geological importance, on 
which the publication of the report enables strong groun 
en. I refer to the conditions under which the Boulder Drift 
of Canada was deposited. It has been customary to refer this 
to the action of ice-laden seas and currents, on a continent first 
subsiding and then re-elevated. But this opinion has recently 
n giving way before a re-assertion of the doctrine that land 
glaciers have been the principal agents in the distribution of the 
tions might be urged against it, and that it was not in accord- 
h the facts which I had myself observed in Nova Scotia 
and in Canada. The additional facts contained in the present 
report enable me to assert with confidence, though with all hu- 
mility, that glaciers could scarcely have been the agents in the 
Striation of Canadian rocks, the transport of Canadian boulders, 
or the excavation of Canadian lake basins. In making thi 
“J 
The facts to be accounted for are the striation and pone 
of rock surfaces, the deposit of a sheet of unstratified clay an 
Stones, the transport of boulders from distant sites lying to the 
its application to such regions as those of the Alps, 
bergen or Greenland, hax ap eared to me inapplicable to the 
drift deposits of eastern America for the following, among other 
1. It requires a series of suppositions unlikely in themselves 
13, , 1864. 
Am. Jour. Sci.—Seconp Sekres, Vou. XXXVIII, No. 113.—Serr-. 
30 
