176 PHYSICAL GEOLOGY. 



thic period; and accounts for this break by showing that there is 

 reason to believe that Palasolithic man lived in Britain during the 

 warm intervals of the first cold period, that he was driven out by the 

 submergence, and that the country was repeopled by Neolithic men 

 after the second glaciation had passed away. 



Other points illustrated are Mr. Croll's theory of the cause of changes 

 in climate, Prof. Eamsay's theory of the origin of Lake-basins, and 

 Postglacial geology. The Drifts of Britain are compared with those of 

 iScandinavia, Switzerland, and N. America. A. H. G. 



Geikie, James. Note on the occurrence of Erratics at higher levels 

 than the Rock-masses from which they have been derived. Trans. 

 Geol. Soc, Glasgow, vol. iv. part 3, pp. 235-241. 



An explanation of the phenomenon in question, based on the fact 

 that the loss in height sustained by a glacier by melting and evapora- 

 tion at the surface is made good by new supplies of ice from behind. 

 Blocks imbedded in the ice are thus carried along a line dipping at a 

 less angle than that of the valley ; and where obstructions impede the 

 flow of the glacier, the lines of ejection will not only become horizontal, 

 but will even curve upwards ; and boulders may thus be extruded at a 

 level higher than that of their starting point. G. A. L. 



GooDCKiLD, J. G. On Drift. Geol. Mag. dec. 2, vol. i. pp. 496-510. 



The object is to discuss the origin of glacial beds. The difficulties in 

 the way of accepting them as submarine are so great that this theory is 

 but barely alluded to. The general idea is that the Till was accumu- 

 lated in sheltered places, under the moving ice- sheet or glacier. Some 

 objections to this are stated ; and it is suggested that the mud, stones, 

 &c. may have accumulated in the ice-sheet. Cross currents of ice 

 often exist, and the flow at the surface may sometimes be in the oppo- 

 site direction to that at the bottom. We may thus account for many 

 apparently anomalous phenomena, as, for instance, the occurrence of 

 Lake-District rocks in the Drift of Galloway, whilst boulders from Gal- 

 loway occur in the Drift of the Lake District. At the commencement 

 of the ice-period, glaciers ploughed up the bottom of the Irish sea, and 

 carried with them the accumulated marine remains of previous periods. 

 These became subsequently imbedded in the ice-sheet, and were carried 

 m the direction in which it moved. The paper enters into details as to 

 how the various kinds of Drift (till, laminated clay, eskers, &c.) may 

 have been formed from the debris included within the body of the ice- 

 sheet. W. T. 



GouLDiNG, P. R. Directions of Frost-striations in Mud. Amer. 

 Journ. ser. 3, vol. vii. p. 245. 



Notices variations in the direction of frost-striae over limestone and 

 granite subsoils respectively, the direction being at right angles to the 

 strike of the rocks. No exj^lanation is attempted. G. A. L. 



Heim, a. Om Gletscherrorelsensteori. [Theory of glacier-motion.] 

 Geol. foren. Stockholm Forhandl. bdt. i. pp. 257-271. 



