DRIFT DIVISION. 
215 
4. Dolomieu supposed that the summits of the Alps and Jura mountains might have been 
once connected by a regular inclined surface of ground, down which the masses may have 
rolled ; and perhaps during the same convulsion that rolled the masses down, the ground has 
been broken, or sunk to assume its present form.* * * § 
5. Venturi sought to explain, their transportation from the summits of the Alps to the valleys 
of the Po, by bringing in the aid of ice, either of glaciers, or of floating ice.* 
6. Some have supposed the Jura mountains to have been on a level with the base of the 
Alps, and that these mountains were elevated, carrying with them the boulders and blocks 
that had been previously tumbled to the base of the Alps.* 
7. M. De Buch, by developing the first theory, and applying it to particular phenomena, 
thought that the dispersion of the erratic blocks was a consequence of the elevation of the 
Alps, posterior to the deposition of the tertiary formations.! 
8. The phenomena of the drift have very generally been attributed to the deluge of Noah. 
9. M. Agassiz, the distinguished naturalist, is now attracting much attention by his attempts 
to explain the transport of boulders and blocks, and the scratched surfaces, by the effects 
produced by glaciers in the Alps and other mountain regions, and applying them to the phe¬ 
nomena observed in England, Scotland, &c. 
10. Another theory, maintained by many distinguished geologists, supposes the phenomena 
of the drift period to be due solely to ancient alluvial action, produced with no greater inten¬ 
sity than the causes acting at the present time. 
11. The phenomena of the drift deposits are attributed to the action of the retiring waters 
of the ocean, as mountain chains were suddenly upheaved. 
12. Another theory attributes the effects to the elevation of the bed of the Arctic ocean, 
which caused a flow of water from the polar region, transporting ice loaded with rocks and 
gravel southwardly over the American and Eastern continent. 
13. Another, proposed I believe by Prof. Esmark^, attributes the phenomena of drift to 
transportation by icebergs; and the scratches, to these, with rocks frozen in and grinding 
upon the bottom, where there was not a sufficient depth of water to float them clear. 
14. Others, to explain the phenomena in the United States, refer the cause to the drainage 
of a vast inland sea through the valleys of the St. Lawrence, Hudson, Susquehannah, Ohio, 
&c.; § and to the sweeping of a debacle from the north,! floating ice with its freight of rocks 
and earth.*ll 
* Brongnuet. Terrains de I’dcorce du globe. Paris, p 829, p, 77. 
t The preceding theories were mostly framed before many investigations had been made, except in the region of the Alps and 
Central Europe. 
t Vide American Journal of Science, Vol. 31, p. 362. 
§ Maclure. American Journal of Science, Vol. 6, p. 98. 
Macluee.. Journal of the Academy of Natural Sciences, Vol. 1, p. 261. 
Tappan. American Journal of Science, Vol. 13, pp. 291, 297. 
Hall. New-York Geological Report, 1840, pp. 431, 444. 
Ackerly on the Geology of the Hudson. Mitchill’s edition of Cuvier’s Theory of the Earth. Et multis aliis. 
II Hildreth, Am. Jour, of Science, Vol. 13, p. 39. Hayden, Geol. Essays. Tho.mpson, Am, Jour, of Science, Vol 23. 
IT Hitchcock. Redfield, American Journal of Science, Vol. 32, p. 351. 
