314 The American Geologist. May, i8S)7 
Glover. Though these surfaces, as above described, are raised 
Pleistocene beaches which have been swept by tides, they ])re- 
sent the only promising field yet recognized for a search for 
glacial grooving in depressed parts of the Puget Sound vallej^, 
and perhaps the only likelihood that some evidences of the 
kind may still be preserved at points beyond all question of 
erosive or frictional effects from local glaciers. 
It was assumed by the late Prof. Newberry (188-4) that 
glaciation of the strait of Fuca was by way of egress of a 
great glacier advancing toward the sea from Puget sound and 
tilling that basin.* An obvious objection to such a theoi-y 
arises from the lack of evidence of the development of an Al- 
pine tract at the head, or to the south, of the latter orographic 
depression during the glacial period, even before base-leveling 
or at any previous epoch of denudation. Contrary evidence of 
a positive character ma}'- be drawn from the fact of gentle 
dips of the superficial carbonaceous sandstone series south of 
the Chehalis divide. Only after recession of an ice mass from 
the strait of Fuca, the excavation of which was largel}^ gla- 
cial, as shown by the florded coast of Vancouver island, could 
the hydrographic drainage of Puget sound axis have been 
effected through the present strait except as a sub-glacial tor- 
rent like that which flows from the Muir glacier at the head 
of Glacier bay. Long after the retreat of a sf)und glacier, an 
ice dam may have been maintained in the strait of Fuca, in 
connection with British ('olumbia survivals of the Cordiller- 
an glacier. 
If, on the other hand, a confluence of local glaciers with a 
projection of the straitof-Georgia, or Cordilleran, glacier took 
possession of the orographic valley now occupied by the 
sound, or even of a similar valley corresponding to the strait 
of Fuca before that present outlet was deepened by erosion ; 
or, again, at a later stage previous to recession of a domi- 
nant ice-mass, it seems natural to suppose that the united 
waters from all sources, of which the sound area was the 
catchment, must have found egress toward the south, necessa- 
rily at a relative higher stage of elevation of that immediate 
area, previous to base-leveling of its fundamental structure. 
To such a stage of superior elevation certain circumstances 
*Proc.N. Y. Acad. Sci., in, 1884, p. 265. 
