86 HISTORY OF THE EUROPEAN FAUNA. 



must have originated in a similar manner; that is to 

 say, by a heavy mass of material containing stones 

 being slowly dragged over the rock-surfaces. The 

 weight which causes the stones to polish the latter is 

 generally ice, but it is quite conceivable that any other 

 substance, especially if it is in a semi-solid state, must 

 act and operate in much the same way. All polished 

 rock-surfaces are carved by glaciers, because we can 

 see them done by glaciers every day, is the argument 

 commonly used nowadays. It was not so formerly. 

 But Mr. Mallet and his views are almost forgotten 

 now; his name does not even appear in our great 

 modern works on the Ice Age. His argument was 

 that as the land rose out of the glacial sea, the mud 

 which had accumulated round the shore slipped 

 downward in a direction determined by the contour 

 of the surrounding valleys and mountains. The 

 moment the land rose above water-level, the large 

 mass of gravel and mud lying upon it slipped down- 

 ward. During a steady rising of the land there would 

 therefore be produced a continuous sliding down of 

 this mud-glacier, which would groove and polish the 

 rock underneath it, in the same manner as the ice- 

 glaciers do in the Alps (p. 47). Professors Sedgwick 

 and Haughton became strong adherents of Mr. 

 Mallet's theory at the time, but it seems later on 

 to have fallen into disfavour with geologists, who 

 may not even be thankful to have it brought to 

 light again. 



