D. Bell — The Great Ice Age and Submergence. 321 



JResume of twelve analyses of glauconite selected from those quoted by Dr. C. 

 Hintze, " Handbuch der Mineralogie," p. 850 (1892). 



Mean. Max. Min. Eemarks. 



SiOa 50-27 58-17 43-00 



FsaOa 17-94 32-80 Nil. Not stated in three analyses. 



AI3O3 5-69 10-09 1-50 



FeO 8-16 21-78 2-64 



CaO 0-78 3-21 Nil. Absent in eight analyses. 



MgO 2-29 6-21 Nil. Absent in four analyses. 



K2O 6-12 8-79 3-10 



Na2 ? 0-91 0-21 Only occurs in two analyses. 



HoO 8-23 14-70 4-71 



99-48 



X. — Notes on " The Great Ice Age " in Relation to the 

 Question of Submergence. 



By DuGALD Bell, F.G.S. 



n^^HE new edition of Dr. Geikie's esteemed work has already 

 JL been noticed at some length in this Magazine.^ The present 

 writer desires to add some notes — freely, but with all respect to 

 the author — on a special part of the subject, viz. that relating to the 

 " high-level shelly deposits," and their bearing on the question of 

 submergence during the Glacial epoch. 



I. 



In his "Fragments of Earth-Lore," published about two years 

 ago, Dr. Geikie intimated that he no longer believed in a " great 

 submergence," during which the British Isles were " largely " sunk 

 nnder the sea. " The marine shells," he said, " in the high-level 

 drift deposits of our islands are 'erratics' carried by the ice-sheet 

 which occupied the basin of the Irish Sea. That the low grounds 

 were submerged to some extent before the advent of that ice-sheet, 

 there seems to be little doubt ; but the amount of the submergence 

 has not been ascertained, — probably it did not exceed a few 

 hundred feet." ^ 



This announcement was extremely gratifying to those who for 

 some yeai's past had been calling in question any " great sub- 

 mergence," and pointing out the striking lack of evidence in its 

 favour. 



It turns out, however, that though Dr. Geikie thus abandoned 

 a "great submergence" of about 1400 feet, which was thought to 

 be proved by " fragments of marine deposits " in Wales and Ireland, 

 he still holds by one of from 500 to GOO feet, which he seems not 

 to consider " great " (though demonstrably it would have placed the 

 British Isles very "largely" under water), and tlie proof of which 

 depends on one or two instances of " high-level shelly clay " found 

 in the west and north of Scotland. Indeed, we may say it now 

 depends on only one instance, for the other is in this edition 

 *' conspicuous by its absence." 



1 See January, 1895. 



2 Op. cit. p. 173. 



DECADE IT. VOL. II. NO. VII. 21 



