Vol. 62.] THE TARN'S OF THE CANTON TICINO. 165 



9. The Tarns of the Canton- Ticino (Switzerland). By Edmund 

 J. Garwood, M.A., Sec.G.S., Professor of Geology in University 

 College, London. (Eead June 7th, 1905.) 



[Plates VII— XXL] 



Contents. 



Page 



I. Introduction 165 



II. The Lakes of the Val Piora 168 



III. The Lago-Tremorgio Group 182 



IV. The St. Gotthard Lakes 184 



V. The Lago d'Elio 187 



VI. General Conclusions 188 



I. Introduction. 



The study of lakes, so long neglected by geographers in the past, 

 has of recent years received a great impetus from the investigations 

 of Prof. Forel, 1 M. Delebecque, 2 Prof. Penck, 3 and other workers 

 on the Continent, and of Prof. Russell, 4 Prof. Gilbert, 5 and Prof. 

 W. M. Davis 6 in America ; while in our own country, Dr. Mill. 7 

 Dr. Marr, Sir John Murray, s Mr. Pullar, and others have aroused 

 our interest in this fascinating subject. 



In his exhaustive ' Handbook of Limnology,' Prof. Forel 

 remarks : — 



' Each lake i3 an organism in itself, each has its peculiarities, its special 

 history in the past and in the present, each deserves a special description. 

 Hence the charm and also the scientific value which attach to the study of 

 lakes in general and to that of each lake in particular.' 9 



Of all the numerous interesting branches of study connected with 

 lakes, that of the origin of the hollow in which the lake occurs 

 is the one that must especially appeal to the geologist ; while of 

 these hollows, those basins that are entirely surrounded by solid rock 

 are certainly the most interesting and the most difficult to explain. 



The theory, originally advanced by the late Sir Andrew Ramsay, 

 and supported by Tyndall, Gastaldi, and de Mortillet, which would 



1 P. A. Forel, ' Le Leman ' Lausanne vols, i-iii (1892-1901). 



2 A. Delebecque, ' Les Lacs Francois ' Paris, 1898. 



3 A. Penck, ' Morphologie der Erdoberflache ' pt. ii (1894) pp. 203-327. 



4 I. C. Russell, ' Geological History of Lake Lahontan ' U.S. Geol. Surv. 

 Monogr. xi (1885). 



5 G. K Gilbert, 'Lake Bonneville' U.S. Geol. Surv. Monogr. i (1890). 



6 W. M. Davis, ' On the Classification of Lake-Basins ' Proc. Boston Soc. 

 Nat. Hist, vol. xxi (1882-83) p. 315. 



7 H. R. Mill, ' Bathymetrical Survey of the English Lakes' Geogr. Journ. 

 vol. vi (1895) pp. 46, 135. 



b Sir J. Murray, ' Bathymetrical Survey of the Freshwater Lochs of Scotland' 

 Geogr. Journ. vols, xxii-xxvii (1903-1906). 



9 'Handbuch der Seenkunde' Stuttgart. 1901, p. 9. 



