Vol. 65.] GLACIAL EROSION IN NORTH WALES. 349 



The cwm-head cliffs, however, were serious difficulties under any 

 theory yet proposed. 



The British preference for British terms might be set against 

 the preference of German geologists for German terms, of French 

 geologists for French terms. Geology and geography were properly 

 international subjects, and the Author's own preference was therefore 

 for an international terminology. He was sorry to learn that the 

 Welsh term, crib, is pronounced creebe, for it was thereby unfitted 

 for general use in its original spelling. 



The transverse bars in glaciated valley-floors, mentioned by 

 M. Allorge, were features to be expected ; they must be produced 

 in a glacial trough, eroded in structures of unlike resistance, but 

 not so maturely eroded as to be well smoothed. The steep slope 

 on the up-stream side of some of these bars was a puzzling feature. 

 Bock-knobs were also, the Author believed, to be regarded as 

 marking immature troughs : had glacial action lasted longer, the 

 trough would have been better smoothed. The objection to the 

 term cycle had been often raised. It did not seem important, 

 because a well-recognized meaning of the word was a long period 

 of time. But it might be pointed out that ' cycle,' as indicating 

 a series of changes that ended about as they began, was very 

 appropriate for plains and plateaux ; and hardly less so for those 

 many mountains which had been eroded from uplifted peneplains, 

 for in the end they would have essentially the same form as in the 

 beginning. M. Allorge's suggestion that it was going too far to 

 speak of ' the indifference of topographic form to the trend of 

 formation -boundaries ' was aside from the point. This statement 

 was not a general theory, but a local induction from observation in 

 the Snowdon district. The further suggestion that this statement 

 resulted from an effort to reduce every type of scenery to a simple 

 formula revealed an unexpected failure on M. Allorge's part to 

 understand the Author's meaning. ' Mature of rocks ' was included 

 under ' structure,' and was considered as a matter of course ; but, 

 around Snowdon, all the rocks were of so resistant a nature, that 

 their influence on form was of secondary importance. It was 

 perceptible, however, in certain rock-steps. 



The example of the steep-headed Maira Valley, southward from 

 the Maloja Pass, in connexion with the hanging lateral valley on 

 its eastern side, pointed out by Prof. Garwood, could not be satis- 

 factorily explained by normal erosion, for the recession of such a 

 valley-head by normal erosion was extremely slow ; and, while the 

 valley-head was receding, the side-valley must have been cut down 

 to grade with the main valley-floor. It was simply inconceivable 

 that a relatively protective glacier could have held its end at the 

 mouth of the side-valley during all the time required for the reces- 

 sion of the valley-head by normal erosion. The explanation for 

 these features, as first suggested by Heim, needed revision, in view 

 of the possibility of glacial erosion. The explanation of certain 

 hanging valleys in the Himalayas by the process of river-capture 



