It
has also been urged, that, without admitting any general glacier-period,
icebergs and floating ice from more northern latitudes might account for
the extensive transportation of the loose materials scattered in a
continuous sheet over a large portion of the globe. There can be no
doubt that an immense amount of _debris_ of all sorts is carried to
great distances by floating ice; where their presence is due to this
cause, however, they are everywhere stranded along the shore or dropped
to the sea-bottom. Large boulders are frequently left by the ice along
the New-England coast, and we shall trace them hereafter among the
sand-dunes of Cape Cod. But before it can be admitted that the
drift-phenomena, and the polished and engraved surfaces with which they
are everywhere intimately associated, are owing to floating ice or
icebergs, it must be shown that all these appearances have been produced
by some agency moving from the sea-board towards the land, and extending
up to the very summits of the mountains, or else that all the countries
exhibiting glacial phenomena have been sunk below the ocean to the
greatest height at which glacier-marks are found, and have since
gradually emerged to their present level. Now, though geologists are
lavish of immersions when something is to be accounted for which they
cannot otherwise explain, and a fresh baptism of old Mother Earth is
made to wash away many obstacles to scientific theories, yet the common
sense of the world will hardly admit the latter assumption without
positive proof, and all the evidence of the kind we have, at the period
under consideration, indicates only a comparatively slight change of
relative level between sea and land within a narrow belt along the
shores; and even this is shown to be posterior, not anterior, to the
glacial phenomena.
Pages:
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216