680 
own Society. In this memoir, estimating the different changes of 
the sea and land, and showing to what extent the solid strata were 
depressed, whose relative histories he thus reads off, he traces the 
shingle beds from the edge of the sea, where they are in process 
of formation, to considerable heights inland; and estimating how 
blocks were transported from the great Cordillera within, or not 
long before the period of existing sea shells, he explains the far- 
transported boulders by their being carried to the spots where they 
lie in vessels of ice. The melting of these icebergs he conceives to 
have been the chief agent in forming such masses of clay, gravel, 
and boulders, as constitute the “till” of Scotland, whilst the con- 
fusion and contortion of their imperfect strata is considered by him 
to be necessarily due to the grounding of icebergs in the manner 
formerly suggested by Mr. Lyell. To the same powerfully disturb- 
ing agent he attributes the general absence of organic remains in 
these deposits ; and, lastly, he infers that it is much more probable 
that the great boulders were transported in icebergs detached from 
glaciers on the coast, than imbedded in masses of ice produced by 
the freezing of the sea. 
M. de Verneuil and myself had previously brought before you 
some new results, arising from our first expedition to Russia. We 
endeavoured to show the utter inapplicability of the Alpine glacial 
theory to vast regions of Northern Russia, though the surfaces of 
the rocks are scored and polished, and far-travelled blocks occur 
throughout a wide area in isolated groups, because much of this 
detritus has travelled over extensive tracts of low country, from 
which it has ascended to levels higher than the sources of its ori- 
gin. Hence we inferred, that the onward persistent march (in 
many parts up-hill) of a body of glaciers, having a front of many 
hundred miles in extent, is irreconcileable with any imaginable sub- 
aerial action. On the other hand, it was proved, by the presence of 
sea shells of an arctic character, that the “terra firma” to which 
some of the blocks had been transported, had been the bed of the 
Northern or glacial Sea at the period of this transport. We then 
attempted to explain how the parallel striz and polishing of the 
surface of rocks of unequal altitudes was reconcileable with the 
submarine action of ice, by supposing that ice floes and their de- 
tritus might be set in motion by the elevation of the Scandinavian 
continent, and the consequent breaking up of great glaciers on the 
northern shores of a sea which then covered all the flat regions of 
Russia ; and we further stated our belief, that the bottoms of these 
icebergs, extending to great depths, must have every here and there 
stranded upon the highest and most uneven points of the bottom 
of the sea into which they floated ; that where the bottom was hard 
rock, the lower surface of the iceberg, like the lower surface of a 
glacier, would grate along and score and polish the subjacent mass ; 
that where the bottom consisted of tenacious mud or clay, the ice- 
berg once fairly stranded would be retained till it melted away, 
entirely or in part, whilst it would be more frequently borne over 
sand-banks, on account of their less resistance. In this manner, we 
