514 
erratic blocks now resting on beds of clay and sand containing recent 
species of arctic shells over large districts in the interior of Russia, 
by supposing “that they had been floated in icebergs, which break- 
ing loose from ancient glaciers in Lapland and the adjacent tracts, 
were drifted southwards into seas which have been since laid dry.” 
He further suggests, that icebergs loaded with detritus may, by grating 
upon the bottom of these seas, have produced the parallel strize and 
polished surfaces on the rocks over which they were drifted ; and con- 
cludes with admitting so much of the glacial theory as to allow that 
in former days glaciers probably advanced further to the south, and 
occupied many insulated tracts, and to a much greater extent than 
at the present day. 
We learn from Professor Hitchcock’s excellent work on Element- 
ary Geology (August Ist, 1840), that parallel striz and furrows, 
accompanied by rounded and polished surfaces of all the harder 
rocks, and that vast longitudinal mounds and tumuli of detritus, and 
erratic blocks sometimes at the distance of many hundred miles from 
their native place, have been lately observed in so many provinces of 
the United States, that these pheenomena may be placed inthe eategory 
of geological constants in North America. They have been noticed 
in Maine, New York, New England, Rhode Island, Massachusetts, 
Connecticut, Ohio, Michigan, and Illinois, at various elevations, 
sometimes from 3000 to 4000 feet above the level of the sea; the 
prevailing direction of these striz and furrows is from N.W.to S.E. 
We have also long been familiar with the streams of erratic blocks 
that have been traced south and south-eastwards from the moun- 
tains of Scandinavia to the shores of Germany ; and more recently 
Sefstrom and Botlingk have informed us that polished striated and 
furrowed surfaces are also of constant occurrence in Norway, Sweden, 
Finiand, and Lapland, their mean direction being, like the course of 
the erratic blocks, from N.W. to S.E. Botlingk, however, has ob- 
served that some of these furrows have centres of dispersion (as in 
the case of those produced by modern glaciers that radiate from the 
Alps), and follow the direction of the major axis of each valley, 
whilst the general direction of the strize on the summits in Scandina~- 
via is from N.W. to S.E. He, moreover, states, that in the south of 
Sweden the striz incline southwards, but on the east of Lapland 
northwards to the icy ocean; the same conformity in the direction of 
the striz with that of the major axis of each valley, occurs also in 
Scotland, Cumberland and North Wales. 
Thus we find, that not only the highest and northern mountain 
groups in the British Islands, but vast regions also of the continents 
of Northern Europe and of North America have been subjected 
to the same great physical forces, glacial and diluvial, under much 
colder conditions of the northern hemisphere than prevail at present ; 
_and this apparently at a time intermediate between the extinction of 
European and American elephants by cold, and the creation of the 
human race. We have not yet, however, sufficient materials for the 
full admeasurement of the amount of influence which has been ex- 
ercised by ice in its various forms upon the surface of the globe, and 
