366 



PROF. "VV. J. SOLLAS ON THE MODE OP [Aug. 1 89 5, 



< 







jj 1 -w 



BO 



<mO 



to 



bJofe 



the course of eighty-seven days the flow across the first line will 

 have amounted to 130 mm. and across the second to 174 mm., 

 ^ m whence it follows that the 



displacements below scarcely 

 amount to more than one-tenth 

 of those at the surface. This 

 is no doubt to be partly ac- 

 counted for by the steep slope 

 down which the material flows 

 on the far side of the barrier, 

 but chiefly, I should imagine, to 

 the resistance offered by the 

 lower layers to shearing. Similar 

 relations are probably to be found 

 in nature, and one is reminded 

 of the rapid movement of the ice 

 on the western slopes of Green- 

 land; the 16 to 60 feet a day 

 which the glaciers accomplish 

 there, as they descend from the 

 interior, may not amount to 

 more, or may be even less, than 

 a tenth of this in the lower 

 layers behind the ' nunataks.' 



It may be observed that 

 nothing resembling ablation oc- 

 curred in this experiment. I 

 did not wish to complicate the 

 problem by removing material ; 

 had I done so I must have 

 taken more away from the lower 

 than the upper regions of the 

 ' glacier,' with the obvious effect 

 of increasing the head of pres- 

 sure under which the pitch 

 moved, and so accelerating its 

 movements both in a vertical 

 and horizontal direction. 



3 £*& 



„o3 oS 



«- o 



§ 2 

 .13 a 



../el 

 <o "q 



3 <o 



i—H 



*+• rs 





a £ 



a 

 II 



a C4H 



c o 



.a 



•3a 



o 



,a 



*§ 



T— 1 



a m 





P £ 



03 



S'-S * 





,q <g 



O 



""-a P 





js*" a 



"3 



6(H OS 





is °pa 



a 



o 



O bX) rt 



p N 



ice-fl 

 inkin 

 Sout 



O 



f the 

 A s: 

 and 







O ..a 









•face 

 tacle 

 unta 





a "> o 





S-§§ 





<D 





.4 





EH 





|> § A I «ll § Probably one of the most sur- 



*•? /\ £ -S.gsc H_ prising results obtained in the 



study of the distribution of 

 glacial boulders is the discovery 

 of travelled stones resting on 

 mountain-sides at considerably 

 higher levels than the parent 

 rock from which they have been 

 derived. Yet the fact is well 

 established, and the evidence of the glacial striae is in many cases in 

 strict conformity with the evidence of the travelled stones. 



