528 HOW FLOATING ICEBERGS HAVE TRANSPORTED ROCKS. 
i 
no moraines, nor any striated and polished rocks in the whole region — effects, as 
they would say, necessarily absent where no glaciers have passed, or as we should 
say, where neither boulders nor gravel have been carried over the surface, by 
water or in floating icebergs. All the north-eastern region of Russia in Europe 
included between the Timan range and the Ural is also, as before said, void of the 
erratics from Scandinavia, but as you approach that crystalline centre the blocks 
are again found, having been extended from it to the east. 
Lastly, the young and adventurous M. Bohtlingk completed, in his short life, 
the proofs on this point, by satisfactorily establishing, that the erratic Scandinavian 
blocks had also been shed off from the coast of Kemi into the bay of Onega, and 
from Russian Lapland into the Icy Sea, both in northerly, north-westerly and 
north-easterly directions ; and thus nearly the whole periphery of their origin 
having been surveyed, we know, that by whatever cause determined, the Scandi- 
navian blocks were on the whole, transported to their present positions by great 
excentric movements. What, then, was the nature of these movements ? If, for 
the reasons already assigned and others on which we shall hereafter dwell, terres- 
trial glaciers be considered agents which can never explain such phenomena, there 
are, it appears to us, only two methods of accounting for such far-borne detritus. 
One of these is the action of drift, by which fragments of mountain chains, dis- 
severed from their parent masses at periods of disturbance and oscillation, have 
been transported to great distances by powerful currents of water ; the other, 
the floating away of ice islands from the edges of chains, formerly encompassed by 
sea-advancing glaciers, which isles, after sailing in certain directions, have dropped 
their loads on the bottom of the sea ; that sea bottom on which the blocks are 
distributed having been since raised into the dry land. Let us consider these two 
operations in reference to the facts with which we are acquainted, and see how far 
each can be made to explain the several conditions under which we find the far- 
transported detritus. 
And first as to icebergs. The examination of the boulders of the north has 
led us to adhere to the belief, which we have long entertained, that there, as in 
central England, the largest blocks were transported to their present positions in 
ice-floes which broke loose from former glaciers. We, therefore, think, that ice 
and snow may, at one time, have covered large parts of Scandinavia and Lapland ; 
that glaciers advanced from thence to the edges of the sea of the post-pliocene or 
block period, and that finally upon an alteration of climate, probably occasioned by 
