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hectares (approximately four square miles) in area, there are in the 
Alps two, in the Juras one, along the Atlantic coast four, and along 
the Mediterranean coast two. Even of lakes more than 250 hectares 
in area (approximately one square mile) there are but thirteen. It 
will be seen therefore that most of the lakes are very small. The tables 
show that the depth of many of them is great in comparison with their 
area. 
IV. Zopography.—The fourth chapter deals with the character of 
the topography and relief of the lake bottoms. Few of the lakes have 
great depth. Lake Geneva has a maximum depth of <4, of its 
length and = of its width, but these ratios are exceeded by many 
of the smaller lakes. The deepest lakes in proportion to their area 
are in the Pyrennees. Here Lac Bleu has a depth of 120 meters with 
an area of but 47 hectares. In the lake bottoms are recognized (a) the 
marginal plains, partly wave cut and partly wave built; (4) the tallus 
slopes (a talus slope of 87° runs down to a depth of 42 meters in one 
case, and aslope of 63° to a depth of 100 meters in another), and (c) 
the bottom flats. In the large lakes the sensible flat (or flats) at the 
bottom is some considerable fraction of the total area. In Lake 
Geneva the bottom flat of an area one twelfth of the total area of the 
lake has a relief of less than five meters. These flat bottoms are nat- 
urally more distinct in the large lakes than in the small ones. Cer- 
tain more or less accidental features are recognized in the topography 
of the lake bottoms. Here are classed deltas, submerged valleys, 
ravines, hills and islands and funnels. The latter are rare, and repre- 
sent either places where springs enter the lake, or where sub-surface 
drainage escapes. Two or three remarkable instances are cited, espe- 
cially in Lac d’Annecy. 
V. Nature of the bottoms.—The nature of the bottom is the topic of 
the fifth chapter. The bottom consists in part of alluvium, and 
in part of the rock in which the basin occurs. ‘The alluvial mate- 
rial is found to vary both microscopically and chemically with the 
nature of the rock of the basin. Numerous tables of results are given. 
The following conclusions are reached: (a) The material at the bot- 
tom of the lake varies with the rock. In limestone basins calcareous 
matter dominates, while in basins in siliceous rocks, quartz is most 
abundant. (4) The mean composition of the sediment in the lake is 
not the same as the mean composition of the rocks in the basin. For 
example, the sulphates are essentially absent in certain lakes whose 
