BOULDER BELTS AND BOULDER TRAINS. 31 



of a dam may lodge on its crest. So, boulders going over a mountain range may 

 lodge there, having beSn carried up by the natural laws of basal flowage. This basal 

 flowage does not affect the general course pursued by the current. It is a very 

 different proposition from the general doctrine of a rise of current. 



In respect to the fringe, I cannot take the time to say what I would be glad to say 

 on the subject; but I regard the fringe in western Pennsylvania as the edge of an 

 old drift, which has there just escaped burying. Traced further west, we find an 

 attenuated drift border for hundreds of miles; we have similar phenomena in the 

 carrying of boulders far out beyond any considerable mass of drift, in some instances 

 very many miles. I may state that along this border from Ohio westward to the Rocky 

 Mountains, we have practically nothing on the edge of the drift that I should denom- 

 inate a terminal moraine. We have, of course, a termination of the drift; but no 

 accumulation such as we have been accustomed to designate a terminal moraine. In 

 the latitude of Bismarck boulders reach westward of any definite terminal 

 moraine to the extent of forty miles, and in the latitude of Pierre there is an exceed- 

 ingly attenuated distribution of boulders, stretching out a dozen miles or more be- 

 yond the thicker distribution on the east side of the river. In the immediate vicinity 

 of the Rocky Mountains, after striking the first boulders from the northeast, I had 

 to travel two hours before finding any others or any signs of northeastern drift. So 

 this phenomenon of attenuated distribution of boulders has a very wide range, and 

 cannot be accounted for, I think, by anything in the line of the suggestions of this 

 paper or of Professor Wright, unless we fall back upon the general proposition that 

 these boulders were transported in the ice, and borne out beyond the point where the 

 ice had the power to push along its subjacent debris. I do not look upon the fringe 

 as being in a proper sense a fringe. I look upon what was called a fringe in western 

 Pennsylvania as the attenuated edge of a drift formation. 



In regard to the transportation of boulders within the ice in different directions 

 from those transported on the face of the ice, I have no considerable mass of data 

 that would answer that question in the affirmative. In the region I have studied the 

 transportation of materials has in general been in practically parallel lines; I have 

 not been able to determine that the englacial currents of the ice were in any essential 

 sense different from those on the surface. I think in general they moved in a common 

 direction. If there were cross-currents, I think they were quite subordinate in the 

 interior region. 



The following paper was then read by Mr. C. D. Walcott : 



STUDY OF A LINE OP DISPLACEMENT IN THE GRAND CANON OF THE 



COLORADO, ARIZONA. 



The paper will be found appended, printed in full. 



The communication represented by the following abstract was then pre- 

 sented : 



ON THE TRAP DIKES NEAR KENNEBUNKPORT, MAINE. 



BY J. F. KEMP. 



[Abstract.] 



The paper opened with a brief reference to the geological reports which touch this 

 region (those of Maine and New Hampshire), and showed that the published material 



