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GEOLOGY: W. E. EKBLAW 
recognized and described several types of soil movement and resultant 
topographic forms. 
In northwest Greenland, solifluction is closely connected with nivation. 
For it is under conditions best suited to nivation that soil flow is best de- 
veloped as a transporting agency. If precipitation be in the form of rain, 
most of the water flows away as surface runoff and its chief work is then the 
characteristic ordinary stream action. But if precipitation be in the form of 
snow — as it is in northern Greenland — which melts rather slowly and gradu- 
ally, little of the water flows away on the surface. Most of it seeps into the 
ground, saturates it, and forms a more or less pasty mass according to the 
relative proportions of soil and water. The presence of an ice-table, in that 
it effectually prevents the seepage of water below the depth of the ice, facili- 
tates soil flow. Thus, perhaps, the principal conditions necessary to soli- 
fluction are snowfall, with gradual melting of the snow, and an ice-table to 
prevent, or at least retard, the seepage of water deep into the ground. 
Several forms of solifluction occur in Greenland, including probably all 
that have been observed elsewhere. Distinction should be made between 
solifluction which causes progressive motion of surface material such as re- 
sults in applanation terraces, solifluction slopes, and soil streams or soil 
glaciers; and that which causes only circulatory movement such as may 
result in 'polygon-boden.' It is the first of these forms of solifluction which 
is one of the most important important transporting agencies in northern 
Greenland, and which has produced there land forms similar to those de- 
scribed by Eakin in Alaska, and by Andersson and others elsewhere. The 
other of these forms is also generally prevalent in Greenland, but while it is 
an active agent of movement contributory to the breaking up and degrada- 
tion of the detritus, it is not so important as a transporting agent. 
Throughout northern Greenland, every land area free of ice and snow during 
the short summer, exhibits the solifluction slopes and applanation terraces 
described by Eakin from Alaska. Both on the slopes and on the plateaus, 
the terraces resulting from solifluction are every where conspicuous. In 
northwestern Greenland, particularly, solifluction of these types is a most 
important transporting agency; the removal of detritus resulting from niva- 
tion, freezing and insolation, to the few torrential streams that bear it on- 
ward to the sea, is quite dependent upon solifluction. In many valleys the 
streams at the bottom of the valleys are not nearly large enough to remove 
the detritus brought down by solifluction, and the valley fast fills up, with 
lakes in the depressions, behind the dams of more abundant, or faster moving, 
detritus. On the gentler slopes, the rate of movement is not high, but on 
some of the steeper slopes the movement is rapid. 
Though the type of solifluction resulting in solifluction slopes and alti- 
plantation terraces is the dominant and most important type in northern 
Greenland, other types are very well represented. From this important 
type to rock slide on the one hand, and to circulatory movement that re- 
