CHARACTERISTICS AND DISTRIBUTION OF LAKKS 645 
basins, called " calderas,"" which are formed when a volcanic cone is 
destroyed by a violent explosion, or is undermined by the liquid lava 
in the core of a mountain. 
Lake of Laach, near the Rhine below Coblenz, lies at an altitude Europe. 
of 750 feet in the Eifel, one of the regions of recently extinct volcanic 
action in Europe. It is an oval cavity, 1^ square miles in area, with 
a maximum diameter of miles, a maximum depth of 174 feet, and 
a mean depth of 107 feet. It has been made to drain by an artificial 
cut into the River Nette, a short tributary of the Rhine, below the 
Mosel. The surface of the surrounding country is strewn with 
fragments from the hollow, but they do not form a distinct crater- 
wall enclosing it. The water has a disagreeable taste, and never 
freezes. 
Lake Lonar is situated on the trap-plateau of the Deccan in Asia. 
India. It is a shallow salt pool at the bottom of a cavity about a 
mile in diameter, and three or four hundred feet deep. On the north and 
north-east sides the edge of the hollow is on a level with the surround- 
ing country ; elsewhere there is a rim of blocks of trap, 40 to 100 feet 
high. The volume of the rim is, however, only about a thousandth 
part of the cavity, and no lava-flow from it can be detected on the 
surrounding surface, so that it must owe its existence in part to the 
effect of subsidence. 
Three lakes, separated by narrow walls, occupy the great crater of 
the Shiranesan of Kusatsu, Northern Japan. The sides of the cone, 
as well as the lake-basins, are composed of grey tuff and sulphur, 
through which in places andesitic rocks crop out in the bold cliffs and 
pinnacles. The crater is oval and nearly half a mile in length, but 
the lakes are circular. The central lake-basin, the water of which is 
boiling in the north-western part, is a quarter of a mile in diameter, 
but all the lakes appear to be diminishing in size.^ The crater of 
Azuma, in the same region, is also occupied by a lake a quarter of a 
mile in diameter. 
North of Lake Nyasa, in a hollow between two ranges of Africa. 
mountains, lies a series of seven volcanic lakes ^ surrounded by extinct 
volcanoes, cinder beds, and hot springs : — 
1 C. E. B. Mitford, " Notes on the Physiography of Certain Volcanoes in 
Northern Japan," Geogr. Journ., vol. xxxi. p. 198, 1908. 
2 See D. Kerr-Cross, "Crater Lakes north of Lake Nyassa," Geogr. Journ., 
vol. v. p. 112, 1895. 
