346 A.K.Wells— 



continuous, and there was no land. Thus he explains the supposed 

 uniformity of the Cambrian and other early faunas ; but he forgets 

 that beneath the Torridonian deposits of Scotland a Precambrian 

 landscape is preserved which shows clear evidence of strong sub- 

 aerial erosion. 



At a later date the covering of Sal was broken and the fragments 

 piled upon one another like ice-floes in a thawing river. But he 

 ofiers no suggestion as to the cause of the breaking or the cause of 

 the piling. In effect his theory really begins with the masses of Sal 

 already constituted, and arranged as in his reconstruction. It begins 

 in fact at the close of the Carboniferous period. 



It would be interesting to discuss the evidence brought forward 

 by Wegener and his coadjutor Koch to show that Greenland has 

 moved perceptibly daring the last hundred years, but this paper is 

 already too long. They assume an accuracy of observation which is 

 unexampled in exploratory survey. It is indeed a curious circum- 

 stance that for many of his most remarkable points Wegener 

 depends upon exploratory survey of one sort or another. Where 

 our knowledge is more precise the evidence is much less striking. 



In conclusion, it may be said that Wegener has performed a 

 valuable service by drawing attention to the fact that land-masses 

 may have moved relatively to one another. He has not proved 

 that they actually have moved, and still less has he shown that they 

 have moved in the way that he imagines. He has suggested much, 

 he has proved nothing. 



The Nomenclature of the Spilitic Suite. 

 Part I: The Keratophyric Rocks. 



By Alfred Kingsley Wells, M.Sc, F.G.S. 



I. Introduction. 



rFHE petrologist who attempts the systematic investigation of 

 -^ igneous rocks is unfortunately too familiar with the difficulty 

 of naming the rocks examined. The discovery of a border-line type 

 necessitates a choice of two alternatives : either the introduction of 

 a new name to a science already overburdened with such, or the 

 widening of the definition of the nearest established type to include 

 the newly described rock. The decision is no easy one to make, 

 especially if the petrographer is young and eager for the transient 

 fame won by the discovery of something new. In such a case the 

 temptation to create a new name is very strong. As a result, both 

 student and teacher spend tedious hours in trying to discover 

 differences between rocks bearing different names, differences which, 

 however, have been magnified out of all proportion to their import- 

 ance as diagnostic characters. 



The second alternative is but little more desirable, the obvious 

 drawback being that the undue widening of a definition destroys the 



