DALY : GEOLOGY OF THE NORTHEAST COAST OF LABRADOR. 261 



dropped again just at the limit where, on account of the depth, the surf 

 is no longer effective in moving boulders resting on the bottom, the 

 erratics would further build up the wall constructed by the undertow. 

 Very close to that limit of effective wave-wash, the winter-ice, because 

 of the depth at which the boulders lie (submerged at high tide), would 

 not be able to buoy up the heavy masses and float them away. 



If the land had, in postglacial time, ever been higher than to-day, 

 erratics won from the wave-swept zone would have moved seaward 

 beyond their present position through the operation of the causes just 

 described. During a subsequent uplift of the land, the boulders could 

 not, in any large number, be recalled to the new shore-line. The actual 

 magnitude of the average barricade is certainly too great to warrant the 

 belief that the waves would, under this condition, undo what they had, 

 during the progress of elevation, accomplished. The character of the 

 material making up the barricade and its organic relation to the wave- 

 swept zone forbid, thus, the assumption of a secondary uplift following 

 a former greater postglacial depression of the land than we now see. 



One is forced to reject the idea that the barricades have been princi- 

 pally formed by 'longshore transport of boulders. The walls are devel- 

 oped very uniformly at the mouth and head, and along the sides of long 

 bays. If they were the result of 'longshoi-e deposition by floating ice, 

 we should expect the accumulation of dropped boulders to be quite 

 uneven, most pronouueed where floes and pans most frequently strand, 

 and, at other points, scarcely begun. It cannot be denied that coast-ice 

 does carry boulders in this way, but one may justly question its ability 

 to have performed so great an amount of work as that demanded in the 

 construction of the barricades. For this hypothesis implies that the sea- 

 floor along the broad track of the annual field-ice is peppered over with 

 glacial erratics far greater in number than could have been furnished by 

 the wave-swept zone, if that zone had had anything like the average 

 proportion of the drift now seen above the highest shore-line. 



Continuance of Elevation. — We cannot doubt that the elevatory 

 process continues in both Labrador and Newfoundland . The almost 

 universal belief of the old settlers on these shores is that in no other 

 way can the changes in depth at familiar localities be explained. With 

 no theory to support or refute, many reputable observers among the 

 fishing population state that they have time and again noted, during 

 periods of from thirty to sixty years, cases where rock-ledges have come 

 perceptibly nearer the sea-surface, where new channels have had to be 

 sought among the shoals for the passage of their fishing-boats, and where 



