ORIGIN OF KAMES AND ESKERS 431 



papers.^ At the present day these processes are exemplified by the Malas- 

 pina Glacier or piedmont ice-sheet in Alaska, which during the last 

 century has been much reduced in area and thickness ; but the Greenland 

 and Antarctic ice-sheets, which are now constant or increasing by snow- 

 fall, have no superglacial drift. 



Conditions of the Origin of Eskers and Kames 



In my first paper on this question, before cited, written 33 years ago 

 and based on my studies in New Hampshire, the rivers forming eskers 

 were thought to be mostly subglacial, although in many instances they 

 were supposed to flow in "deep channels along lines of depression upon 

 the surface of the glacier/^ The latter explanation, however, soon ap- 

 peared to me preferable for all the eskers that then and subsequently I 

 have examined, while quite short ridges and knolls or hills of the same 

 gravel and sand, called kames, are ascribed to sudden and brief deposi- 

 tion by such ice-walled rivers close to their mouths.^ 



Believing that the ice-sheet nearly everywhere contained much engla- 

 cial drift, I deem the absence or very rare occurrence of boulders in the 

 gravel and sand of eskers and kames to be a conclusive argument against 

 their subglacial deposition. Nowhere except on the western part of Birds 

 Hill have I found or learned of an esker enveloped with till, as would 

 apparently be common if these gravel ridges were formed beneath the 

 border of the departing ice-sheet. Because only the west end and north 



^ Proceedings of the American Association for the Advancement of Science, vol. xxv, 

 for 1876, p. 218 ; vol. xxviii, for 1878, pp. 299-310. 



Geolosry of New Hampshire, vol. iii, 1878, pp. 9, 10, 175-176, 285-309. 



Final Report of the Geological and Natural History Survey of Minnesota, vol. 1, 

 1884, pp. 440, 603-604 ; vol. ii, 1888, pp. 252, 254-256, 409-417. 



Bull. Geol. Soc. Am., vol. 3, 1892, pp. 134-148 ; vol. 4, 1893, pp. 191-204 ; vol. 5, 

 1894, pp. 71-86 ; vol. 6, 1895, pp. 343-352 ; vol. 7, 1896, pp. 17-30 ; vol. 8, 1897, pp. 

 183-196. 



American Geologist, vol. x, 1892, pp. 339-362; vol. xil, 1893, pp. 36-43; vol. xlv, 

 1894, pp. 69-83 ; vol. xvi, 1895, pp. 100-113 ; vol. xix, 1897, pn. 411-417 ; vol. xx, 1897, 

 pp. 383-387 ; vol. xxiii, 1899, pp. 369-374 ; vol. xxv, 1900, pp. 273-299. 



Proceedings of the Boston Society of Natural History, vol. xxvi, 1893, pp. 2-17. 

 8 Geology of New Hampshire, vol. iii, 1878, pp. 12-14, 43-48, 62, 71, 76, 84-93, 99, 106- 

 108, 115. 117, 127, 137-138, 144. 147, 155. 162, 167-170, 174-176. 



Final Report, Geological and Natural History Survey of Minnesota, vol. i, 1884, pp. 

 444, 582, 624; vol. ii, 1888, pp. 168, 185, 234, 486. 4P0. 550. 



Proceedings of the American Association for the Advancement of Science, vol. xxvlli, 

 for 1879, pp. 303-304. 



Proceedings of the Rochester, New York, Academy of Science, vol. II, 1893, pp. 181- 

 200. 



Bull. Geol. Soc. Am., vol. 12, 1894, pp. 71-86. 



American Geologist, vol. xiv, 1894, pp. 403-405. 



U. S. Geological Survey Monograph xxv. The Glacial Lake Agasslz, 1895, pp. 157, 

 179, 182-188, 210. 



