(517/8. "Trans. R. Soc. Edinb."
Volume XVI., page 395, 1847.) in 1847 upheld the view that the ledges
represent the shore-lines of lakes which were imprisoned in the valleys
by dams of detrital material left in the glens during a submergence
of 3,000 feet, at the close of the Glacial period. Chambers, in his
"Ancient Sea Margins" (1848), expressed himself in agreement with Mr.
Darwin's marine theory. The Agassiz-Buckland theory was supported by
Mr. Jamieson (517/9. "Quart. Journ. Geol. Soc." Volume XIX., page 235,
1863.), who brought forward additional evidence in favour of the glacial
barriers. Sir Charles Lyell at first (517/10. "Elements of Geology,"
Edition II., 1841.) accepted the explanation given by Mr. Darwin, but
afterwards (517/11. "Antiquity of Man," 1863, pages 252 et seq.) came to
the conclusion that the terrace-lines represent the beaches of glacial
lakes. In a paper published in 1878 (517/12. "Phil. Trans. R. Soc."
1879, page 663.), Prof. Prestwich stated his acceptance of the lake
theory of MacCulloch and Sir T. Lauder Dick and of the glacial theory
of Agassiz, but differed from these authors in respect of the age of the
lakes and the manner of formation of the roads.

The view that has now gained general acceptance is that the parallel
roads of Glen Roy represent the shores of a lake "that came into being
with the growth of the glaciers and vanished as these melted away."
(517/13. Sir Archibald Geikie, loc. cit., page 269.)

Mr. Darwin became a convert to the glacier theory after the publication
of Mr. Jamieson's paper. He speaks of his own paper as "a great
failure"; he argued in favour of sea action as the cause of the terraces
"because no other explanation was possible under our then state of
knowledge." Convinced of his mistake, Darwin looked upon his error as
"a good lesson never to trust in science to the principle of exclusion."
(517/14. "Life and Letters," I., page 69.)

LETTER 517. TO C. LYELL. [March 9th, 1841.]

I have just received your note. It is the greatest pleasure to me to
write or talk Geology with you...

I think I have thought over the whole case without prejudice, and
remain firmly convinced they [the parallel roads] are marine beaches. My
principal reason for doing so is what I have urged in my paper (517/15.
"Observations on the Parallel Roads of Glen Roy, and of other parts of
Lochaber in Scotland, with an attempt to prove that they are of Marine
Origin." "Phil. Trans. R