EPISODE:
CAMMIN, POMERANIA (KAMIEN POMORSKI, POLAND), 1804
Debates about the origin(s) of valleys, the causes of recent extinctions, and about the origin of superficial deposits seemed difficult for geologists to resolve one way or another: opinion was divided between natural processes acting as they presently do, or a natural global catastrophe of some kind (generally a flood). Erratics seemed difficult to explain by contemporary natural processes.
Erhard Georg Friedrich Wrede (1766-1826) examined "erratic" boulders on the shores of the Baltic (just as de Luc had), including the one depicted here. To judge by the rock type, these rocks had come from Sweden and Finland: but how could they have moved across the Baltic Sea? In his "Geognostical researches relative to the countries on the south of the Baltic, and particularly to the low lands in the mouths of the Oder, with observations on the gradual change of the level of the sea in the northern hemisphere, and on its physical causes" (1804), Wrede sought an answer that was based in careful observation and in slow "still active causes" rather than sudden, "unusual revolutions."
He speculated that at one time Earth's axis had tilted, raising sea levels in the Baltic as the region found itself under the ocean's "equatorial bulge." If the climate had been colder at the same time, then the huge blocks could have drifted across on ice-floes to perhaps land across much of the North German Plain. Wrede was the first to suggest this mode of transportation.
The "Royal Boulder" on Chrzaszczewska Isle, Kamien Pomorski, Poland.
http://www.geo.uw.edu.pl/ZASOBY/GEOIMAGE/GLACIER/erratic.jpeg
QUESTION:
If you accept this "drift" explanation do you also have to accept his underlying cause of transgression of the sea (the sea covering the land)?
REFERENCES
de Luc, J.A. 1810 Geological travels vol.1 (Rivington, London), p-34-37 http://www.google.com/books?id=se44AAAAMAAJ&pg=PP7
Hall, J. 1812 On the Revolutions of the Earth's Surface, being an account of the diluvian facts in the neighbourhood of Edinburgh. Part 1 Transactions of the Royal Society of Edinburgh, v. 5, 1812. p. 139-167; Part 2 1812, v. 7, p.169-211
http://vinyl2.sentex.ca/~tcc/GT/Hall.html
Wrede, E.G.F. 1804 Geognostische Untersuchungen über die Südbaltischen Länder, besonders über das untere Odergebiet: nebst einer Betrachtung über die allmählige Veränderung des Wasserstandes auf der nördlichen Halbkugel der Erde und deren physische Ursachen (Berlin, Schuppel) [Geognostical researches relative to the countries on the south of the Baltic, and particularly to the low lands in the mouths of the Oder, with observations on the gradual change of the level of the sea in the northern hemisphere, and on its physical causes]
REVIEW: Allgemeine
Literatur - Zeitung num.57, Montags den 10 Junius 1805, p.586-587
http://zs.thulb.uni-jena.de/receive/jportal_jparticle_00027512
