522 



SCIENCE. 



[N. S. Vol. IV. No. 93- 



Saxicava, etc. , in the moraine now being con- 

 structed as well as in the ice itself. These 

 occur at all elevations from sea level to 

 600 feet, but the configuration of the re- 

 gion is such that this may not mean a re- 

 treat of more than one or two miles. 



Notwithstanding this retreat and ad- 

 vance, the glacier is now engaged in a rapid 

 withdrawal. The evidence of this is found 

 in moraines 100 or 200 feet from the ice 

 front, in some of which an ice core still ex- 

 ists, while in all cases the withdrawal has 

 been so recent that the boulders have not 

 become lichen-covered. The same is true 

 of the bed rock between the moraines and 

 the ice. 



This very recent retreat is a part of a 

 general withdrawal of a vast ice sheet, 

 which extended outward beyond the Duck 

 Islands, a distance of no less than 32 miles 

 from the front of the Cornell glacier. The en- 

 tire Nugsuak peninsula has been so recently 

 glaciated that striated rocks are still present 

 even at the outer end. Boulders of slate, 

 quartzite and porphyritic granite- rocks, no- 

 where found in place on the Nugsuak, occur 

 abundantly in the moraine of the glacier 

 and are strewn over the peninsula. The 

 granite was also found on the Duck Islands 

 in a bed of till. At the Devil's Thumb,which 

 rises 2,600 feet above the sea, transported 

 blocks of the granite were found, and they 

 are abundant at the top of the highland of 

 Wilcox Head, 1,400 feet above the sea. 

 Therefore, granting a depth of no more than 

 100 fathoms for the fjord south of the Nug- 

 suak, there has recently been an ice sheet 

 here covering all of the land and having a 

 depth of no less than 2,000 feet, and prob- 

 ably much more. At the Duck Islands, 8- 

 10 miles farther from the mainland, and 32- 

 34 miles from the present ice front, the ice 

 sheet had a depth of no less than 800 feet, 

 and probably much more. 



So, in this part of Greenland at least, the 

 present glaciation is a shrunken remnant of 



a former greater sheet, the western limits of 

 which cannot be drawn. At Disco Island, 

 at an elevation of 2,000 feet, gneiss boulders 

 rest on trap ; and, while they may have 

 been brought from within the island, it is 

 equally possible that they were brought 

 from the direction of the mainland. It will 

 be an interesting point to decide how exten- 

 sive this greater glaciation has been. It 

 seems hardly probable that it was local. 



Various detailed observations were made 

 along the margin of the glacier and upon 

 the direction of movement in the ice as 

 well as of the ice over the peninsula. One 

 of the most marked features noticed is the 

 remarkable control which topography has 

 upon ice movement, especially in the last 

 stages of the ice. In one case the move- 

 ment of an ice tongue of the main ice cap 

 is moving in exactly the opposite direction 

 from the general movement of the ice which 

 supplies it. The general movement is one 

 thing, the deviation from this induced by 

 larger topographic features is quite another,, 

 and the influence of minor topographic 

 features in the very last stages is still 

 another ; but while one gains much in the 

 way of valuable hints from a study of the 

 Greenland ice sheet, he must needs be very 

 cautious in his application of these to our 

 own recent glaciation. The conditions are 

 very difierent, and in no way is this more 

 markedly shown them in the decided poverty 

 of drift in the control of the Greenland ice 



The thanks of all connected with the ex- 

 pedition are due to Lieut. Peary for the 

 sagacity with which his plans were laid and 

 executed. The terrors of Arctic naviga- 

 tion, of which we have all learned so much,, 

 do not appear in his summer trips ; and, 

 judging by this summer and the several 

 preceding ones, an expedition to Greenland 

 under the lead of Lieut. Peary is as safe 

 and pleasant a summer excursion as one 

 to Alaska. The expedition went and re- 

 turned on schedule time, and this has beens 



