354 



SCIENCE. 



[N. S. Vol. XV. No. 374. 



other parts of the Alps retreat is the rule. 

 The meager records from Scandinavia indi- 

 cate general retreat for the glaciers which have 

 been under observation. The few available 

 records from the United States (including 

 Alaska), Canada, Greenland and Russian Asia 

 indicate the same phase of glacier movement. 

 In the Himalayas there has been liltle change 

 observed in recent years. More extensive ob- 

 servations, carried on through long periods of 

 time, are much to be desired. 



A significant conclusion has been reached by 

 Myron L. Fuller'--" in his studies of the glacial 

 drift of eastern Massachusetts. He finds evi- 

 dence of two distinct sheets of till, the lower 

 being differentiated from the upper, both 

 physically and lithologically. The physical 

 difference is such as to indicate that the un- 

 derlying sheet of till was subjected to extensive 

 decay before the overlying sheet was deposited. 

 This conclusion is in harmony with the recent 

 interpretations put upon the drift in other 

 parts of the State by other geologists, and with 

 the interpretations which have long been given 

 to the drift of the Mississippi basin. 



Glaciation has been determinedf in Siberia 

 between the parallels of 35° and 36°, and near 

 the 93d meridian there is evidence of glacia- 

 tion in an area about one hundred square miles 

 in extent. Among the glacial features are 

 drumlins and cirques. Elsewhere cirques oc- 

 cur in the high Altais, and glaciers are now 

 found in the same mountains about the sources 

 of the Irtish River, near the Mongolian bor- 

 der, at elevations of about 10,000 feet. 



Several points of interest in connection with 

 the Pleistocene glaciers in the western part of 

 the United States have been determined during 

 the past year.:): 



Mr. Wallace W. Atwood has been studying 

 the glacial drift of the Wasatch mountains, 

 and has determined the positions of 50 Pleis- 

 tocene glaciers exceeding a mile in length. Of 



* ' Probable Representatives of Pre- Wisconsin 

 Till in Southeastern Massachusetts,' Jour, of Oeol., 

 Vol. IX., pp. 311-329, 1901. 



t ' A Single Occurrence of Glaciation in Siberia,' 

 Am. Geol., Vol. XXVII., pp. 45-47, 1901. 



% ' Glacial Work in the Western Mountains in 

 1901,' by Rollin D. Salisbury. Jour, of Geol., Vol. 

 IV., pp. 718-731. 



these, ten exceeded five miles in length; four- 

 teen descended to an altitude of less than 6,000 

 feet, and seven to an altitude of 5,000 feet. 

 Seven of these glaciers reached the shore-line 

 of Lake Bonneville. The elevation necessary 

 to give rise to a glacier was about 9,000 feet. 

 Mr. Atwood and his party also found that the 

 drift of the Wasatch mountains is referable to 

 two distinct epochs of glaciation. In the val- 

 ley of the North Fork of the American Fork, 

 the two sheets of drift, produced by glaciation 

 from nearly opposite directions, are separated 

 by a soil thicker than that which covers the 

 surface of the upper sheet of drift. Other 

 evidences of the duality of the glacial period 

 in this region are found in the unequal weath- 

 ering to which different parts of the drift have 

 been subjected, and in the unequal amount of 

 erosion which the drift of different localities 

 has suffered. 



Pleistocene glaciation has been determined 

 in the mountains of New Mexico near Santa 

 Fe. The glaciation, so far as determined, was 

 between the parallels 35° 45', and 36°, and 

 between the meridians of 105° 35' and 105° 

 50'. Within this area, the positions of some- 

 thing like 50 Pleistocene glaciers have been 

 determined, chiefiy by Messrs. John Webb and 

 William A. Averill. Study was carried far 

 enough to indicate that local glaciation was 

 the rule, in the vicinity of altitudes reaching 

 or exceeding 12,000 feet. Some of the glaciers 

 reached a length of several miles. The glacial 

 features found in this region are such as are 

 developed by small mountain glaciers. 



Pleistocene glaciers were found to have ex- 

 isted on the north slopes of the Spanish Peaks 

 of Colorado. The glaciers here were less ex- 

 tensive than might have been anticipated from 

 the elevation of the mountains, but their small 

 size is probably the result of the small extent 

 of the areas attaining the requisite height. 



In northwestern Montana, east of the Rocky 

 mountains, Mr. F. H. H. Calhoun has studied 

 the relations of the drift deposited by the Kee- 

 watin ice sheet to that deposited by the gla- 

 ciers coming out to the eastward from the 

 mountains. It appears from his work that the 

 Wisconsin drift extended somewhat farther to 

 the westward than has been supposed, reach- 



