358 PREHISTORIC EUROPE. 



attain a thickness in England of several hundred feet. In Scot- 

 land the accumulation must also have been considerable, but 

 during the succeeding glacial epoch all the Scottish deposits were 

 scoured out by the ice, only a few patches being left here and there 

 in the inland districts, while in the low-lying maritime regions, 

 where, for reasons already given, the grind of the ice was less 

 intense, the marine beds occur in better preservation, while the 

 till that overlies them is often charged with shells belonging to 

 different zones, which are rolled, crushed, broken, and scratched, 

 just like the glaciated stones with which they are commingled. 

 Here and there, too, we come upon horizontal rock-ledges cut in 

 the face of hill-slopes that look out upon the sea — platforms and 

 terraces which are evidently the work of the waves. But the 

 interglacial age of these is shown by the fact that they are 

 glaciated and coated here and there with boulder- clay. In 

 Norway so intense was the glacial erosion that not a scrap of 

 any marine deposit pertaining to the last interglacial epoch has 

 been preserved, but it is possible, as I have suggested, that 

 many of the ancient strand-lines (which are often smoothed-off 

 and faintly-marked, while at least one of them shows glacial 

 striae) may have been formed contemporaneously with the 

 similar rock -terraces in Scotland and the "middle sands and 

 gravels " of Lancashire and Cheshire. In Wales the interglacial 

 beds have been ploughed out by the glaciers, as Ramsay long 

 ago showed, and in the more elevated parts of Northern England 

 they have likewise been demolished. The same, too, is the case 

 in Ireland. But in the lower-lying districts they appear often 

 in more or less continuous sheets underneath the upper boulder- 

 clay, which, like that of Caithness and the north of Lewis in 

 Scotland, is often charged with marine exuviae. It is needless 

 to say that relics of ancient interglacial land-surfaces have been 

 even less well preserved. Yet both in Scotland and England 

 we come upon patches of terrestrial accumulations containing 

 mammalian, molluscan, and vegetable remains, while in the till 

 itself bones, tusks, and horns, and fragments of wood have been 

 detected, which must have been rolled forward under the ice 



