LECTURE XI. 323 



tlie seaj or are found as terminal barriers in the valleys. The sea 

 rose about five hundred feet ; for up to this height we find 

 deposits of molluscs, which belong to the Arctic sea. These 

 enormous ice-masses furnished, at the same time, large streams, 

 which here and there obstructed by the terminal embankments 

 of the glaciers, formed large inland lakes, and deposited the finely- 

 ground material, carried by them, in the form of loam, marlj and 

 sand-clay. The sea on the one hand, and the inland lakes on the 

 other, worked on the masses deposited by the ice; the glaciers 

 brought down erratic blocks, and these were either directly or 

 indirectly, after floating on the icebergs, deposited upon the 

 banks. Thus the present period was gradually induced, when 

 glaciers stretch to the sea in but few spots, but rise in other 

 places considerably above the sea-level, and where in the 

 valleys a milder climate prevails. 



This pre-historic history is no romance ; it is derived from 

 actual facts and the deductions therefrom. The facts are thus 

 summarised by Kjerulf : 



" What is the prevalent order of the glacial deposits ? Quite 

 at the bottom, where they could not be washed away, are sand 

 and pebbles. This is ' sheiier-sancV (scoring-sand), and ' sclieur- 

 steine' (scoring-stones). This is the material which, pressed 

 by the ice, was carried above the rocks. These blocks should 

 be examined, if we wish to estimate the direction of the mo- 

 tion. But as for the most part they are smaller, much broken, 

 and frequently rounded, they are termed pebbles (rolled 

 stones), though this is an incorrect name, they should there- 

 fore be distinguished as ' scheuer-steine.' They are not 

 rolled, but have been crushed against each other, and being 

 inserted into the ice, like diamonds in the glazier's pencil, 

 they have drawn lines and furrows upon the stones. Above 

 this ' scheuer-sand' and the pebble banks he the various kinds 

 of clay, first, calcareous, marly clay, in districts accessible to 

 the glacial waters which brought down the ground up hme and 

 clay from the Silurian beds ; next above, the shell-clay, where 

 the elevation was not too high ; then comes brick-clay, without 

 shells, derived probably from the period when the flood from 



y2 



