698 



JVO on IVOR TH A ND MA RBUT 



gram, Fig. 6, representing the highest part of Cat Rocks. The 

 structure of the bowlder belt at Cat Rocks is, therefore, wholly 

 consistent with the theory of its glacial origin, and the evidence 

 of this exists not only in the main pile but also in the fringe 

 above described. 



It would throw some light on the mode of accumulation of 

 these bowlders if it could be determined whether they were 



^- Af.W. 



Fig. 6. — Diagrammatic section of highest part of Cat Rocks. A, zone of small 

 scattered bowlders. B, zone of piled bowlders. C, zone of scattered bowlders left by 

 the melting of the ice-sheet. D, position of the ice front. 



dropped from an ice cliff as englacial or superglacial matter or 

 were extruded from the base as subglacial debris. It was hoped 

 that we might find criteria in the occurrence of bruised markings 

 due to the violent contact of bowlders which had fallen out in 

 the process of accumulation. The weathering of the blocks, which 

 are largely gneisses and coarse granites, has, however, proceeded 

 so far as to remove the original surface of the rocks where 

 exposed to view, and the points of contact of the larger 

 bowlders are not accessible for examination ; so that this point 

 has not been determined. 



The northward or inner edge of the belt exhibits a mural contact 

 with the ice frojit. — No feature in the distribution or accumulation 

 of the bowlders at Cat Rocks is more suggestive of the glacial 

 origin of the accumulation and of the particular relation of the 

 deposit to the ice-sheet than the sharply defined northern wall 

 which is here and there shown. The photograph reproduced in 

 Fig. 5 is a view taken from the intraglacial field about sev- 

 enty-five feet north of the moraine looking S. S. E, at this 

 mural inner edge where best developed. Nowhere on the 



