Reports and Proceedings—Geological Society of London. 237 
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ORS ASN») er © CHD EIN GS: 
Grotogicat Socrety oF Lonpon. 
March 27th, 1967.—Sir Archibald Geikie, D.C.L., Sc.D., Sec.R.S., 
President, in the Chair. 
The following communications were read :— 
1. ‘On the Southern Origin attributed to the Northern Zone in 
the Savoy and Swiss Alps.” By Professor T. G. Bonney, Se.D., LL.D., 
BARS. E.Gesat 
Professor Lugeon, with some other‘eminent Continental geologists; 
explains certain peculiar flat folds, the higher of which sometimes 
project considerably beyond the lower, in the more northern 
sedimentary zone of the Swiss and Savoy Alps, by supposing that to 
no small extent the strata have been thrust forward from an original 
position south of the watershed of the Pennine-Lepontine Alps; 
overriding, as they advanced, their crest and that of the Oberland 
(neither having then attained its present altitude). This pressure 
was produced by the greater thickness of deposits of Mid-'lertiary 
age, speaking in general terms. Professor Sollas, in concluding 
a very interesting and suggestive paper on some experiments with 
cobbler’s wax, published in the last volume of the Quarterly Journal 
of the Society, p. 716, suggests that the results are favourable to the 
views of the Lausanne professor. 
The author takes exception to some of the cases, especially two to. 
the east of the Simplon Pass, which are adduced by Professor Lugeon 
in support of his hypothesis, pointing out that he has confused an 
ordinary with a crystalline limestone, and merely schistose slates with 
true crystalline schists. But, without going into the details of 
sections, he shows from general reasoning that both the kind and 
the amount of transport, postulated by Professor Lugeon, introduce 
serious mechanical difficulties. Sediments are assumed to have been 
transported from (say) near Ivrea to the northern margin of the Alps 
on either side of the Rhone valley below Martigny ; that is, to have 
travelled something like 75 miles. As the average thickness of the 
Secondary and older Tertiary strata in this part of the Alps can 
hardly exceed 2-5 miles, we can form a general idea of the problem 
by drawing an oblong 30 times as long as high. Then, material at 
one end (southern) has to be squeezed across obstacles to near the 
other, by piling a wedge-like mass of sediment on a southern 
prolongation of the oblong, the thin end of which mass may perhaps 
trespass a little on the northward side of the original southern 
boundary. 
After discussing the problem in some detail, the author shows that 
in Professor Sollas’s experiments there was, at the beginning of 
loading, a wedge instead of an chlong; the distance to be traversed 
was six times the maximum thickness of the (supposed) sedimentaries, 
imstead of about 30 times; and the slope of the added mass was about 
double that which, in the Alpine case, is supposed to -be the sole 
