Correspondence — R. M. Deeley — R. G. A. BuUeriveU. 525 



favour of his theory and resorts to microscopic evidence in its 

 difficulties. The popularity of this method of settling problems 

 which concern the roots of all geological reasoning is assured, if 

 only the exclusive discussion of authors whose decisive sections are 

 totally erroneous by their own testimony can be persistently 

 maintained. 



P. W. Stuaei-Menteath. 

 St. Jean de Lxjz. 

 September 15, 1908. 



GLACIER GRAINS. 



Sir, — I have pointed out ' that in caves cut in the ice of glaciers, 

 and also on the surfaces of glacier ice at high altitudes in places 

 protected from the sun, the glacier grains are finely striated, the 

 striations on different grains running in various directions. As each 

 glacier grain is a distinct more or less strained crystal, it seemed 

 advisable to determine whether the surface striations produced by 

 evaporation bear any relationship to the crystalline structure of the 

 ice grains. 



Tyndall has pointed out that when, by means of a burning glass, 

 the sun's rays are focussed in ice, liquid discs or flowers appear in 

 the interior. These discs or flowers would, of course, be at right 

 angles to the optic axis. I, therefore, last August, from the upper 

 cave of the Rhone Glacier, cut samples of ice which showed these 

 striations, and then by means of a burning glass produced the liquid 

 discs within. In all cases these discs proved to be parallel with the 

 external striations. One crystal in particular showed this very 

 clearly. It was cut from a prism of ice and was striated on three 

 sides. ]^ot onlj^ were the striations on these faces in agreement, 

 but the liquid discs produced by the sun's rays throughout the 

 interior of the ice were in all cases in the same plane as the striations 

 on the surfaces. 



R. M. Deeley. 



THE OCCURRENCE OF FLINTS IN AN OLD GRAVEL- BED NEAR 

 NEWBIGGIN-BY-THE-SEA (NORTHUMBERLAND COAST). 



Sir, — Some years ago I first found flints in this deposit. 

 Previously their presence had been unknown, and, so far as I am 

 aware, nothing has since been published concerning them. The 

 gravel-bed is of pre-Glacial age and lies upon sandstone of the 

 Coal-measures, the only available section being that exposed in the 

 cliffs between Newbiggin and the mouth of the Eiver Wansbeck. 

 Here it may be traced for a distance of 480 feet. At its northern 

 boundary it is seen to rest against an ancient cliff running in 

 a direction normal to the present sea-front, and at this point the- 

 gravel is over 18 feet thick, the total height of the cliff being 22 feet.. 



1 Geol. Mag., 1907, p. 529. 



