5B. THE GEOLOGICAL SOCIETY'S "GLACIAL" DEBATES, 1840-1841

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". . . the distribution of blocks and gravel, as well as the polished and striated surfaces of rocks in situ, do not indicate the action of a mighty current flowing from north-west to south-east, as the blocks and masses of gravel everywhere diverge from the central chains of the country, following the course of the valleys" (Agassiz, 1840, p.328).

In late 1840, Agassiz, Buckland (who was President), and Lyell gave papers reporting on their conclusions from their studies in Scotland.

Agassiz continued to argue, as he had done since Neuchatel in 1837, "that glaciers did not descend from the mountain summits into the plains, but are the remaining portions of the sheets of ice which at one time covered the flat country. It is evident . . . if the glaciers descended from high mountains, and extended forward into the plains, the largest moraines ought to be the most distant, and to be formed of the most rounded masses; whereas the actual condition of the detrital accumulations is the reverse, the distant materials being widely spread, and true moraines being found only in valleys connected with great chains of lofty mountains." Thus he continued to see lowland glaciation as primarily a static sheet of ice ("nappes").

Interestingly, Agassiz suggested there might some validity to views previously expressed by Lyell concerning the "drift" mechanism:

“It must then be admitted . . . that the disappearance of great bodies of ice produced enormous debacles and considerable currents, by which masses of ice were set afloat, and conveyed, in diverging directions, the blocks with which they were charged . . . the Norwegian blocks found on the coast of England have been correctly assigned by Mr. Lyell to a similar origin.”

At each reading debate ensued, particularly at the November 4 reading. Here, too, Buckland "did not explain all diluvial phenomena by the operation of glaciers; he allowed the existence of . . . drift-ice, but contended that glaciers alone would account for many phenomena observable in Scotland, &c. He discussed the possibility of . . . debacles spreading the detritus still further."

Discussion at GSL was not recorded in order to allow the free-flow of ideas, but notes of the discussions following papers by Agassiz, Buckland and Lyell were made by S. P. Woodward, then sub-curator to the Geological Society, and they were printed in the Midland Naturalist, vi. 1883, pp. 225-29.

The reading of the papers was not the triumph that perhaps Buckland and Agassiz had anticipated and, as it turned out, their papers were never published as Lyell and then Buckland withdrew them. What is available are accounts in which some of the more uncompromising and extravagant claims were cut (Boyland, 1988). There was simply too much opposition to the ideas.

The account of the debate was reproduced by Woodward (1908) and should be read there, pages 134-144 (http://books.google.com/books?id=cyjAAAAAIAAJ&pg=PA134 ).

Debate at the GSL (de la Beche)

As you read, consider the following:

• Were the facts in doubt?
• What is the method of argument used by Agassiz contrasted with that of Murchison?
• How does Whewell characterize the manner in which the glacial theory is being offered?
• Buckland makes what point against its opponents?
• How does knowledge of climate and climate change play into this? Can you accept a theory even if such details are lacking?
• How does North American evidence play into the arguments?

REFERENCES

Agassiz, L. 1840 Glaciers, and the evidence of their having once existed in Scotland, Ireland, and England. Proceedings of The Geological Society of London v.III (Nov. 1838 to June 1842), Part II (1840-1841), no.72 p.327-332
http://www.google.com/books?id=giPPAAAAMAAJ&pg=PA327

Boylan, P.J. 1998 Lyell and the dilemma of Quaternary glaciation. p.145-159 in D.J. Blundell, S.C. Scott (eds.) Lyell: the past is the key to the present The Geological Society, London, Special Publication 143 (GSL, London) http://sp.lyellcollection.org/cgi/reprint/143/1/145.pdf

Buckland, W. 1840 Memoir, On the evidences of glaciers in Scotland and the north of England. Proceedings of The Geological Society of London v.III (Nov. 1838 to June 1842), Part II (1840-1841), no.72 p.332-337 (part 1), 345-348 (part 2)

http://www.google.com/books?id=3qoEAAAAQAAJ&pg=PA332

http://www.google.com/books?id=3qoEAAAAQAAJ&pg=PA345

Lyell, C. 1840 Memoir, On the geological evidence of the former existence of glaciers in Forfarshire. Proceedings of The Geological Society of London v.III (Nov. 1838 to June 1842), Part II (1840-1841), no.72 p.337-345 http://www.google.com/books?id=3qoEAAAAQAAJ&pg=PA337

Thackray, J.C. (ed.) 2003 To see the Fellows fight: Eye witness accounts of meetings of the Geological Society of London and its Club, 1822-1868. The British Society for the History of Science Monograph 12 (BSHS, London)

Woodward, H.B. 1908 The history of the geological society of London (Longmans, Green & Co., London) http://books.google.com/books?id=cyjAAAAAIAAJ&pg=PA134

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