344 PROF. W. MORRIS DAVIS ON C^Ug. I909, 



A. J. Jukes-Beowne. 'The Age & Origin of the Plateaus around Torquay' 



Quart. Journ. Geol. Soc. vol. Ixiii (1907) pp. 106-23. 

 A. Penck & E. Beucknee. ' Die Alpen im Eiszeitalter ' Leipzig, 1901-1908. 

 J. Playfaie. ' Illustrations of the Huttonian Theory of the Earth ' Edinburgh, 



1802. 

 A. C. Ramsay. 'On the Denudation of South Wales & the Adjacent Counties 



of England' Mem. Geol. Surv. Gr. Brit. vol. i (1846) pp. 297-335. 

 . ' The Old Glaciers of Switzerland & North Wales,' in ' Peaks, Passes, & 



Glaciers ' London, 1859. 

 . ' The Geology of North Wales ' Mem. Geol. Surv. Gr. Brit. vol. iii (1866) ; 



2nd ed. 1881. 

 €. Reid & J. S. Fiett. ' The Geology of the Land's End District ' Mem. Geol. 



Surv. Eng. & Wales (Expl. of Sheets 351 & 358), 1907. 

 E. Richteb. ' Geomorphologische Untersuchungen in den Hochalpen ' Peterm. 



Mitth. Erganzungsband xxix, Heft 132 (1900-1901). 

 E. Whympee. ' Scrambles amongst the Alps in the Years 1860-69 ' 2nd ed. (1871). 



EXPLANATION OP PLATE XIV 7 . 



Outline-map of the Snowdon district, on the scale of approximately 1: 70,000. 



Discussion. 



Dr. Marr stated that, as the result of the Author's instruction 

 in the English Lake District (presenting features so similar to 

 those in the area described in the paper), he was bound to 

 acknowledge that he (the speaker) had greatly under-estimated 

 the effects of glacial erosion. He referred to Mr. Alfred Harker's 

 papers in the ' Geological Magazine ' for 1899 and the Trans. Hoy. 

 Soc. Edin. 1901, as giving views similar to those advocated by the 

 Author. He no doubt spoke the feelings of all present, when he 

 expressed his pleasure at hearing so luminous a paper from the 

 Society's distinguished Eoreign Correspondent. 



Mr. T. Crook remarked that the Author had compared the 

 hypothetical pre-Glacial relief of the Snowdon group with certain 

 subdued and much rounded types to be seen in Carolina and else- 

 where. He would like to ask what type of rock and structure 

 prevailed in the subdued mountain-system of Carolina to which the 

 Author referred in making this comparison. He raised this 

 question, because it was obviously important that, in framing 

 assumptions as to any probable former type of relief in a mountain- 

 system, the influence of rock-variety and structure as determining 

 factors should be considered. In stating the character of what he 

 termed a normally subdued and non-glaciated type of relief, the 

 Author apparently ignored these factors. As bearing on this point, 

 the speaker further asked whether an actual example could be 

 given of a mountain-system, having the Snowdonian type of rock and 

 structure, which had, under similar climatic conditions, developed 

 a relief resembling that which the Author had assumed to exist 

 in the Snowdon group during pre-Glacial times. 



M. M. Allorge said that he had been charmed by the lucidity 

 of the Author's description of the Snowdon district and by his 

 series of skilful diagrams on the blackboard, conveying so vivid a 

 sense of the three dimensions, and illustrating the morphological 



