350 M. Escher de la Linth on certain Phenomena 



a great extent, rays very nearly horizontal, and from one and 

 a half to four millimetres broad. In the very wide hollows of 

 these rays, small and transverse notches may be seen, almost 

 always more or less curved, usually about 0"" 3 distant from 

 each other, their convexity constantly turned up the valley. 

 These notches have all the appearance of the trace of an in- 

 strument like a chisel, which, moved by a slow mechanism, 

 and somewhat tremulous action, presses against the substance 

 submitted to its action, sometimes more and sometimes less 

 strongly. I believe that no one, on seeing this appearance, 

 would hesitate to ascribe it to a very slow movement, similar 

 to that of glaciers, and to consider it altogether incompatible 

 with a rapid movement. 



The polished rock near Pfeffers, cleared a little while since 

 by a rivulet from the detritus which covered it and protected 

 it hitherto against the influence of the atmosphere (fig. 6, 

 Plate III.), presents still another peculiarity. Very nearly per- 

 pendicular to the furrows which follow the general direction of 

 the valley, we perceive numerous striae all very fine, of a depth 

 more appreciable, sensibly parallel to each other, and running 

 in the direction of the greatest acclivity. These stria? cross 

 the longitudinal furrows in some places in so distinct a man- 

 ner, that we perceive they are of newer formation. I know 

 not what explanation the advocates of currents would give of 

 this circumstance. In the theory of glaciers, it presents it- 

 self as the result of the slow movement which the detritus of 

 the surface of the glacier has been subjected to, during the 

 sinking and melting of the glacier, that is to say, during its 

 transport from a b to c d, fig. 7, Plate III. 



In short, it appears to me that M. Durocher's objection to 

 the production of furrows and striae by the action of glaciers 

 are by no means plausible, and that the circumstances men- 

 tioned above prove, on the contrary, that it is glaciers which 

 have produced them, or, if such a view of the matter be pre- 

 ferred, an agent still altogether unknown, which gave rise 

 to effects absolutely identical with those of glaciers. 



I refrain from entering into a comparison of mounds and 

 erratic deposits with the deposits of glaciers, and from shew- 

 ing that the transverse erratic mounds most distant from the 



