MICHIGAN ACADEMY OF SCIENCE. 51 



SOIL STRIPES IX COLD HUMID REGIONS, AND A KIXDRED 



PHEXOMEXOX. 



WILLIAM II. IIOBBS. 



Attention was first strikingly directed to snrface rock flowage as a 

 characteristic degradational process in liuinid regions and high latitudes 

 by Professor J. G. Andersson of the University of Upsala/ For this 

 process, the importance of which had not before been adequately recog- 

 nized, he proposed the name soUfiuction- {solum, soil; ffeure, to flowi. 



rlking examples of the process he had himself studied in detail from 



nr Island (741/2° X. latitude), and from the Falklands (52° S. lati- 



^^ude). where are the famous "stone rivers." These streams of mixed 



c debris and clay, while bearing considerable resemblance to the 



..id rivers" early mentioned by Hayden from the Xorth American 

 Rockies and more recentl}' described in detail by Howe,- are consider- 

 ably longer and narrower and relatively thicker. 



Andersson's paper, which is a preliminary notice, discusses the larger 

 characteristics only of these interesting streams of rock debris. In 

 one i)lace, however, he refers to a streakine.*«s of the surface of the 

 moving rock debris on Bear Island. X'^ordenskjold," on the other hand, 

 lias furnished us with much new and general information concerning soli- 

 fluction, both as regards the localities described by Anderson and others 

 which he has himself examined. 



Speaking in general of the surface of the.^e flows, Xordenskjold says: 



"Often there appears upon the slopes of hills a band-like arrangement of the 

 debris. If one examines it more closely, he perceives that these bands consist 

 of irregularly heaped up masses of angular stones, debris and clay slime, which 

 extend almost from the summit of the hill down to the valley, where they 

 stretch out after the manner of glaciers and push ahead of them a true terminal 

 moraine of rock splinters which are cast aside" (page 61). 



A fine example of surface striping by this ju-ocess X'ordenskjold has 

 figured from Graham Laud (PI. 2, B.), and he refers to a similar observa- 

 tion made long before in Greenland. Of this latter example he says: 



"I found that the debris on steeply inclined slopes often had a peculiar arrange- 

 ment. The slope appears as though striped, because narrow generally parallel 

 bands of finer or coarser debris or clay alternate in close sequence. The entire 

 earth-mass is ordinarily well sorted, so that each band as a rule consists of 

 equally large sand grains or stones" (pp. 62-63). 



These bands continue down the slope in more or less serpentine 

 courses becoming always fainter, however, as the gradient becomes 

 flatter and passing finally into a peculiar net-like aiTangement of the 

 debris on the lower levels. 



^J. G. Andersson, Solifluction, a component of subaerial denudation. Jour. Geol.. Vol. 14, 

 1906, pp. 91-112. 



-Ernest Howe, Landslides in the San Juan Mountains, Colorado, including a consideration 

 of their causes and their classification. Professional paper No. 67 U. S. Geol. Surv., 1909, 

 pp. 1-58. 



^Otto Xordenskjold, Die Polarwelt und ihre Nachbarliinder. Leipzig, 1909, pp. 60-65. 



