22 EEPORT— 1881. 



But the progress in our knowledge of geography is, and has been, by 

 DO means confined to the improvement of our maps, or to the discovery 

 and description of new regions of the earth ; bat has extended to the causes 

 which have led to the present configuration of the surface. To a great 

 extent indeed this part of the subject falls rather within the scope of 

 geology, but I may here refer, in illust'-ation, to the distribution of lakes, 

 the phenomena of glaciers, the formation of volcanic mountains, and the 

 structure and distribution of coral islands. 



The origin and distribution of lakes is one of the most interesting 

 problems in physical geography. That they are not scattered at random, 

 a glance at the map is sufficient to show. They abound in mountain 

 districts, are comparatively rare in equatorial regions, increasing in num- 

 ber as we go north, so that in Scotland and the northern parts of 

 America they are sown broadcast. 



Perhaps a priori the first explanation of the origin of lakes which 

 would suggest itself, would be that they were formed in hollows resulting 

 from a disturbance of the strata, which had thrown them into a basin- 

 ehaped form. Lake-basins, however, of this character are, as a matter 

 of fact, very rare ; as a general rule lakes have not the form of basin- 

 shaped synclinal hollows, but, on the contrary, the strike of the strata 

 often runs right across them. My eminent predecessor. Professor 

 Ramsay, divides lakes into three classes: — (1) Those which are due to 

 irregular accumulations of drift, and which are generally quite shallow. 

 (2) Those which are formed by moraines, and (3) those which occupy 

 true basins scooped by glacier-ice out of the solid rock. To the latter 

 class belong, in his opinion, most of the great Swiss and Italian lakes. 

 Professor Ramsay attributes their excavation to glaciers, because it is of 

 course obvious that rivers cannot make basin-shaped hollows sun'ounded 

 by rock on all sides. Now the Lake of Geneva, 1,230 feet above the 

 sea, is 984 feet deep, the Lake of Brienz is 1,850 feet above the sea, and 

 2,000 feet deep, so that its bottom is really below the sea-level. The 

 Italian lakes are even more remarkable. The Lake of Como, 700 feet 

 above the sea, is 1,929 feet deep. Lago Maggiore, G85 feet above the 

 sea, is no less than 2,625 feet deep. It will be observed that these lakes, 

 like many others in mountain regions — those of Scandinavia, for instance 

 — lie in the direct channels of the great old glaciers. If the mind is at 

 first staggered at the magnitude of the scale, we must remember that the 

 ice which scooped out the valley in which the Lake of Geneva 'now re- 

 poses, was once at least 2,700 feet thick ; while the moraines were also 

 of gigantic magnitude, that of Ivrea, for instance, being no less than 1,500 

 feet in height. Professor Ramsay's theory seems, therefore, to account 

 beautifully for a large number of interesting facts. 



The problem is, however, very complex ; and, while admitting the 

 force of Professor Ramsay's arguments, there are, no doubt, other causes 

 which have exercised a considerable influence in the arrangement and 

 configuration of lakes ; for instance— as has been ably argued by our 



