88 LTE fOOLKINALE OL, GHOZOGN,. 
Those which finally remain, when the ice has deposited its load, 
will be only those which were last named, or those which escaped 
destruction. As successive sets of striae on drift stones are oblit- 
erated, new ones taking their places, the stones become smaller. 
If the process be continued long enough, astone may be completely 
worn out. The product of the wear would be rock-flour. Rock- 
flour, the product of glacial grinding, is carried on beneath the 
ice, and constitutes an earthy or clayey matrix, in which the 
accompanying stones and bowlders are imbedded. It is identical 
with the ‘‘clay”’ in which the bowlders are seen to be imbedded on 
the land from which the ice has receded. It is comparable in 
all respects to the matrix of our bowlder-bearing clays. 
If one is fortunate enough to go beneath the ice at the point 
where a stream issues, it may be seen that the stream, even while 
its course is beneath the ice, is carrying such material as its 
velocity enables it to transport, and that it is continually dropping 
parts of its load. The deposits made by flowing water beneath 
the ice are stratified, as the deposits of running water always are. 
Should the ice crowd out over the stream’s bed, as is possible, 
displacing the water in the operation, such parts of the stratified 
deposits as were not ground up and borne away by the ice might 
be buried beneath the unstratified deposits which it might make. 
Since this process of change may be repeated, ice succeeding 
water, and water ice, at any given point, we discover at least one 
way in which alternations of stratified and unstratified deposits 
may be brought about in connection with glacier ice. 
The flowing water beneath the ice does not stop with the 
terminus of the glacier itself, but issues as a swift river, hurrying 
on down the valley, with such load of sediment as it can Carry. 
These materials are spread out in alluvial plains beyond the edge 
of the ice, wherever the stream is unable to carry them further. 
Considerable plains of stratified material have been built up in 
this way by the ice-born rivers, beyond the ends of many alpine 
glaciers. In some cases they extend many miles down the 
valleys, the coarser materials being near the ice and the finer 
further away. In every essential particular concerning constitu- 
