Review of Recent Geological Literature. 377 
observation and study, the element of floating-ice has been gradually 
eliminated, and all the phenomena now find explanation by means of 
land-ice and "schmelz-wasser" alone, that is, by the ice-sheet and the 
water produced by its melting. The marine shells that are found 
rarely in the German stony clays, along with mammalian bones and 
fresh water shells, have been shown to be derivative in their origin, 
being just as much erratics as the stones and boulders with which 
they are associated. 
Following the summary by Dr. Jentzsth of the present opinions of 
German geologists, the author notes that the northern regions, as the 
Scandinavian peninsula, Lapland and Finland, were the feeding- 
grounds of the ice-sheet. "In those regions melting was at a min- 
imum, while the grinding action of the ice was not ei?ective. * * * * 
Further south melting greatly increased, while ground moraine at the 
same time tended to accumulate, the conjoint action of glacier-ice and 
subglacial water resulting in the complex drifts of the peripheral 
area. In the disposition and appearance of the aqueous deposits of 
the 'diluvium' we have evidence of an extensive subglacial water cir- 
culation, glacier-mills that gave rise to 'giants' kettles,' chains of 
subglacial lakes in which fine clays gathered, streams and rivers that 
flowed in tunnels under the ice. and whose courses were paved with 
sand and gravel. * * * * The dove-tailing and interosculation of 
boulder-clay with aqueous deposits are explained by the relation of 
the ice to the surface over which it flowed. Throughout the peripheral 
area it did not rest so continuously upon the ground as was the case 
in the inner region of maximum erosion. In many places it was tun- 
nelled by rapid streams and rivers, and here and there it arched over 
subglacial lakes, so that accumulation of ground moraine proceeded 
side by side with the formation of aqueous sediments. * * * * Now 
a stud}' of the ground moraines of modern glaciers affords us a reas- 
onable explanation of such differences. Dr. Briickner has shown that 
in many places the ground moraine of Alpine glaciers is included in 
the bottom of the ice itself. The ground moraine, he says, frequently 
appears as an ice-stratum abundantly impregnated with silt and rock- 
fragments, — it is like a conglomerate or breccia whichhas ice for its 
binding material. When this grouml-moraine melts out of the ice — 
no running water being present — it forms a layer of unstratilied silt or 
clay, with stones scattered irregularly through it. Such being the 
case in modern glaciers, we can hardly doubt that over the peripheral 
areas occupied by the oil northern ice-sheet boulder-clay must fre- 
(piently have been accumulated in the same way. Nay, when the 
ground-moraine melted out and dropped here and there into quietly 
flowing water, it might even acquire in part a bedded character." 
Professor Geikie also believes that the drifts of middle and southern 
England, which exhibit the same complexity, will eventually be gen- 
erally acknowledged to have had a similar origin. 
The interglacial beds of northern Germanv contain remains of a well 
