Correspondence — Mr. James Geikie. 139 



ORIGIN OF LAKE BASINS. 



SiR^ — I observe that Mr. Judd, in the January Number of the Geo- 

 logical Magazine ("On the Origm of Lake Balaton in Hungary"), 

 asserts that he has " demonstrated that the basins of the largest lakes 

 in our islands, in the Alpine regions of Europe, and in equatorial 

 Africa, respectively, could not 'possibly have been formed by the sup- 

 posed excavating power of ice." (The italics are Mr. Judd's.)^ He 

 has also '' shown," he says, '' that in each of these cases there is the 

 strongest ground for believing the districts in question to have been 

 subjected to powerful subterranean movements ; and that these were 

 quite competent to produce the depressions in question." Finally, 

 he waxes still bolder in the statement of his beliefs, and is evidently 

 of opinion that all smaller rock-basins must have originated in the 

 same way. What, then, is that magic process of reasoning which 

 has enabled Mr. Judd to arrive, with so much confidence, at these 

 uncompromising and comprehensive conclusions, and the cogency of 

 which has appeared to him so great as to justify some very positive, 

 not to say dogmatic, utterances, and a general oracular tone which 

 is surely rather de trop? Briefly stated, his argument is as 

 follows : — 



Lake Balaton (30 or 40 feet in depth) occupies a depression, the 

 longer axis of which coincides with a line of volcanic action ; Lough 

 Neagh probably lies in a preglacial hollow ; the Valley of the Jordan, 

 with its lakes (Merom, Tiberias, and Asphaltites), is probably an area 

 of subsidence : Victoria Nyanza may perhaps owe its origin to vol- 

 canic disturbances : 



These lakes represent the principal types of lake-basins which 

 exist upon the earth : 



Therefore rock-basins " may have had their origin in those changes 

 of level resulting from the subterranean movements which have 

 accompanied volcanic action ; " and, " as a matter of fact, the largest 

 lakes in the British Islands and in the Alpine regions of Europe, 

 respectively, and not improbably the vast sheets of water in Central 

 Africa also, have been so formed, and could not possibly be the result 

 of glacier- erosion." (These italics are mine.) 



This is certainly a remarkable argument, but of a kind which, if 

 it were taken for a model, might lead to curious results. For ex- 

 ample, it would not be difficult to " demonstrate," after this manner, 

 that all men are born in lawful wedlock. Thus : — 



A is a good man, B is a bad man, is neither good nor bad but 

 indifferent : all three may have been, and were, T believe, born in 

 lawful wedlock : 



A, B, and C represent very fairly the principal types of men : 



Therefore, men may have been born in lawful wedlock, and, '' as a 

 matter of fact," all are legitimate, and none can possibly be the off- 

 spring of unmarried parents. 



Now I ask whether this brilliant syllogism is a whit less feebly- 

 forcible and convincing than the argument upon which Mr. Judd 

 has founded so much strong language. Exception might easily 

 be taken to many of the author's statements, but it is not 



