522 ROBERT ANDERSON 



of the streams owes its origin more probably to one of the first-men- 

 tioned causes, or to the aid afforded by structural weakness to erosional 

 work. 



LIST OF LARGE CRATERS 



A review of the Hterature on volcanoes reveals the fact that there 

 are very many craters and volcanic depressions comparable with the 

 Aso caldera in form and origin. The frequency of occurrence and 

 importance of this type has not received adequate recognition in most 

 of the textbooks. The following list gives the dimensions of some 

 of the largest known craters, and of a few smaller ones that are typical 

 calderas, out of the hundreds of large craters that might be cited. It 

 is probable that the majority of these mentioned are volcanic sinks — - 

 have resulted, that is, from the subsidence of portions of volcanic 

 mountains — -and may therefore be termed calderas. 



Monte Albano, in Italy, has a ring wall inclosing a crater 7 by 6 

 miles in dimensions. 



Lago di Bolsena and Lago di Bracciano are crater lakes in Italy, 

 the former measuring 8.5 by 7.5 miles, and the latter being round and 

 with a diameter of 5.5 miles. 



On Vesuvius, the old crater of Somma must have been nearly cir- 

 cular and 3 miles in diameter. 



Val del Bove, on Mt. Aetna in Sicily, is a caldera 4 or 5 miles in 

 diameter.^ 



Pantellaria, between Sicily and Africa, has traces of a crater ring 

 12 miles in diameter.^ 



Santorin, in the Mediterranean, is a volcanic ring 18 miles in cir- 

 cumference. 



Palandokan, in Armenia, has a crater with long axis of 6 

 miles. 3 



Dyngufjoll, in Iceland, has a crater about 8 by 4 miles in dimen- 

 sions with an area of 25 square miles.'^ 



1 Charles Lyell, Principles of Geology, loth ed., Vol. I, p. 630. 



2 G. Poulett Scrope, Volcanos, 1872. p. 429. 



3 Hermann Abich, Geol. Forschungen in den kaukasischen Ldndern, Theil II, 

 Vienna, A. Holder, 1878-87. 



4 Th. Thoroddsen, Geog. Journ. (London), Vol. XIII, Nos. 3 and 5, March and 

 May, 1899. 



