678 ABSTRACTS OF PAPEES 



That this vigorous local glaciation occurred before and not after the regional 

 glaciation of the range is indicated by 1 1) the absence of valley moraines at 

 the cirque mouths and i2.> the extension of the regional ground moraine far 

 up their floors. Rock falls and avalanches hav- pseudo-morainic effect 



to the upper portions only of the cirque floors. 



of a former existence of local glaciers in the White Moun- 

 tains is thus supported by new facts : but these glaciers seem to have been 

 very much shorter than hitherto supposed, and instead of having existed in a 

 closing stage of the last glacial epoch they seem to have operated in an early 

 : r quite probably in an earlier epoch. 



Disccssio>- 



Mr. Fravk Leveeett inquired whether I Idthwait had found a suit- 



able explanation for the growth of local glaciers in the Mount Washington 

 region in advance of the invasion of that region by the continental ice-sheet. 

 He also asked whether Doctor Goldthwait had found evidence that the wind- 

 deepened valleys that had held the local glaciers were free from ice when the 

 continental ice-sheet moved across them. 



Prof. H. F. PvEir»: Professor Goldthwaifs paper supplies me with some in- 

 formation regarding the position of the snow-line during the retreat of the 

 great ice-sheet which I have long wanted to have. When Mount Washington 

 was uncovered by the retreat of the ice. glaciers would have been formed on 

 its flanks if the snow-line were somewhat lower than the summit and the fact 

 that no such glaciers were formed shows that the snow-line must have been at 

 an altitude of 6 ? 000 feet or more when Mount Washington was uncovered. 

 On account of the sloping surface of the ice the snow-line must have oeen 

 e distance farther to the north. 



Prof. J. B. Woodworth : On the Island of Marthas Vineyard there is evi- 

 dence of a long interglacial epoch of erosion between the Wisconsin and the 

 next preceding epoch of glaciation. If these cirques on Mount Washington 

 were produced by local glaciers prior to this interglacial epoch, their walls 

 seemingly should have been notched by gullies and corries. which may still 

 D part as evidence of non-glacial action prior to the advent of the 

 □ iea The absence of these non-glacial erosion features would be 

 - lined to mean that the local glaciers preceded the Wisconsin immediately 

 or by a time so short that weathering and rain action produced no such effect 

 in any recognizable degree. 



GEOLOGICAL SECTIOX ALONO THE YUEOX-ALASEA BOUNDARY BETWEEX 

 YUEOX AXD PORCUPIXE RIYERS 



BY D. D. CAIRXES 



{Abstr* 



The geological - :ion> conducted during the past two summers along 



the Yukon-Alaska International Boundary (the 141st meridian), between Yu- 

 kon and Porcupine rivers, have shown that the rocks there are dominantly of 

 :nentary origin, and include Meeozoic, Paleozoic, and probably Archean 

 members, the entire Paleozoic section being apparently represented. 



