48 



a tale to tell against their being of glacial origin) is that the 

 striae on the rock-surface in no case are prolonged below the 

 recent deposits, unless where they are of sub-aerial origin. 

 Such proofs strongly lead me to believe that the stricT in 

 question are not of ice origin, but were effected by other 

 agencies at a period subsequent to that of the last great ice 



As a further corroboration of the opinion that these striae on 

 the rock-surface at Black Point are not of glacial origin, on 

 revisiting the locality I discovered about fifty yards north- 

 easterly, in the bed of a small stream, similar markings to 

 those observed at Black Point, showing evident signs of their 

 having been effected by atmospheric and aqueous agencies ; 

 with this marked difference, however, that they were impressed 

 upon the rock-surface in the direction of nearly east and west. 

 This fact still further convinces me of the opinion that some 

 of the beds in that neighbourhood are not composed of equally 

 destructible materials, so as to withstand the wear of time in a 

 uniform degree. The markings on the top of the sea-cliffs, to 

 my mind, are referable to atmospheric and aeolian agencies, 

 whilst those of the watercourse have been caused by the com- 

 bined action of the atmosphere and the little streamlet. 



