1865.] SIR R. L'MURCHISON ON GLACIERS. 25 



lands. In this country it has indeed met with the most vigorous 

 opposition on the part of Dr. Falconer, as recorded in our proceed- 

 ings : and even Sir Charles Lyell, the great advocate of the power 

 of existing causes, has stoutly opposed this bold extension of a most 

 powerful vera causa* Having explored the Alps, at various in- 

 tervals, for upwards of forty years, I long ago came to the conclu- 

 sion that their chief cavities, vertical precipices, and subtending, 

 deep, narrow gorges, were originally determined by movements 

 and openings of the crust, whether arranged in anticlinal or 

 synclinal lines, or not less frequently modified by great transversal 

 or lateral breaks, at right angles to the longitudinal or main folds 

 of elevation and depression. Explorations of other mountainous 

 regions, in various parts of Europe, have strengthened this convic- 

 tion. I rejoice, therefore, to find that those geologists of Switzer- 

 land, who justly stand at the head of their profession, Professor 

 Studer and M. Escher von der Linth, have sustained, by numerous 

 appeals to nature, the views I hold in common with the great 

 majority of geologists. Those Swiss explorers, who have labored 

 for many years in their native Alps, and have constructed admi- 

 rable geolological maps of them, must surely be well acquainted 

 with the ruptures of the various rocks, the outlines of which they 

 have sedulously followed. Now, they attribute most of those deep 

 cavities in which the rivers and lakes occur, either to dislocations 

 producing abrupt fissures, or to great foldings of the strata leaving 

 openings upwards where the tension has been the greatest — open- 

 ings which were enlarged by powerful denudations. Numerous 

 geologists have recently expressed their concurrence in the generally 

 adopted view, that the Alpine lakes occupy such orographic depres- 

 sions ; and by close researches, my accomplished friend, Mr. John 

 Ball f has ably sustained this view, and has further shown how 

 slight is the erosive power of a glacier even when issuing from its 

 main source. No one of them in short, any more than Professor 

 Studer and myself, doubts that the origin of these lakes is primar- 

 ily due to other causes. Nor am I aware that any geologists of 

 France and Germany, much as many of them have examined the 

 Alps, have deviated from the opinion that the main diversity of 

 outline in that chain was due to ruptures and denudations that 

 occurred during the upheavals of the chain. 



* See ' Antiquity of Man,' pp. 316 et seq. 

 t See < Phil. Mag.' 1863. 



