96 REVIEWS 
the Juras, and the Vosges Mountains, one in the central plateau, and 
one in the Pyrenees ; (4) lakes which result from the blocking of a lateral 
valley by the moraine of the glacier which occupied the main valley. 
Of this there are representatives in the Alps. the Juras, and the Pyrenees ; 
(c) lakes which lie in basins occasioned by the irregular deposition of 
drift. But two lakes fall into this category, one in the Alps, about which 
there is some question, and one in the Juras. In our own country 
lakes of this class are more numerous than any other. (4) Lava. 
Several lakes, the basins of which are formed by lava dams, are found 
in the central plateau. (5) Volcanoes. Two lakes in the central 
plateau owe their origin to growth of volcanoes in the bottoms of 
valleys. (6) Crazers. Several lakes in the central plateau occupy 
craters. (It is not altogether clear why crater lakes should be classified 
among the lakes produced by barriers). (7) Azver alluvium. Lakes 
formed along rivers by the deposition of alluvium are represented by a 
few lakes in the Alps, Juras and along the Mediterranean coast. (8) 
Bars. A few lakes on the coast owe their origin to the construction of 
bars which shut off a portion of the sea water, leaving inland basins. 
(9) Dunes. There are several lake basins completed by dune barriers 
along the Atlantic coast. 
Of the lakes which occupy basins in the rock, one group owes 
its origin to internal forces. In this category belong the basins pro- 
duced (1) by violent volcanic disturbances, such as explosions, of which 
there are several examples in the central plateau; and (2) lakes pro- 
duced by secular movements. To this class belong several lakes in the 
Alps (Geneva and d’Annecy), and in the Juras, though concerning the 
origin of the latter there seems to be some question. Of the lake basins 
originating through the action of external forces, there are (a) those 
resulting from solution effected by underground waters, represented in 
the Alps and along the Atlantic coast, in the Juras, along the Mediter- 
ranean, and in one or two other places; (4) lakes due to erosion of 
rock along fissures, as where a fissure crosses a watercourse; and 
(c) basins due to excessive local erosion by the ice, represented in the 
Alps by several examples, in the Juras by one possible example, in 
the Vosges by one, in the central plateau by several, and in the Pyrenees 
by a considerable number. Here belongs Lac Bleu, of extraordinary 
depth. It is probable that in the production of many of the lake 
basins more than one factor has been involved. 
