222 Professor Forbes on the Leading Phenomena of Glaciers, 



an inclined convex surface, but that it is indented by furrows 

 or wrinkles, which would give a section like figure 2., in a 



Fig. 2. 



direction parallel to the length of th,e glacier A B, fig. 1, the 

 dots here indicating the snow wreaths as before, and the 

 broken lines approximating to the direction of the frontal dip 

 of the veined structure in this part of the glacier. These 

 periodical undulations (to use a technical scientific term) are, 

 beyond question, very important in the theory of glaciers 

 generally, and of the dirt bands in particular. Their existence 

 will, probably, be thought to yield some confirmation of the 

 theory of semifluid motion of the ice, even although their pre- 

 cise origin be still obscure. A homely comparison, but a 

 striking one, may be found in the twinkles of the horns of many 

 animals ; and, though it may appear fanciful, there is perhaps 

 more than a vague analogy between the facts. I hope, at 

 some future time, to offer a better elucidation. 



After some stay at Chamouni, I proceeded, by easy journeys, 

 to Grindelwald, whose beautiful and easily accessible glaciers 

 I had not visited for many years. I there found an exact 

 confirmation of the views which I have published respecting 

 the origin and structure of glaciers. I found the forms, simple 

 and compound, of the ribboned structure, to be such as I have 

 described, including the gradual rise of what I have called 

 the " frontal dip," from a very low angle near the lower end of 

 the glacier, up to 75° towards its origin, especially on the 

 Glacier of the Strahleck, above the Zasenberg, where it forms 

 the Mer de Glace of Grindelwald. The other principal affluent 

 of that icy sea, viz. the glacier descending from the Viescher 

 horner, exhibits the same wrinkles exactly as those which I 

 have just described upon the Glacier du Geant, perhaps even bet- 

 ter marked. As the lower glacier of Grindelwald furnished an 

 excellent example of all the modifications which I have else- 

 where shown to belong to the canal-shaped glacier, with 

 branches ; so the upper glacier is an exact representative, in its 



