172 Dr Martens on the Glaciers of 'Spitzbergen 



general somewhat convex, and which were entirely paved 

 with prisms placed vertically by the sides of each other. Their 

 length varied from fourteen to thirty centimeters, the greater 

 part being from one to two decimeters ; their diameter was 

 from one to two, rarely of three, centimeters. Their upper 

 surfaces were perfectly level. Almost all resembled each 

 other in shape, which was that of a prism with a square or 

 hexagonal base ; but their faces and angles were unequal and 

 mal accusees. Being simply in juxtaposition, although very 

 close to each other, they fell of their own accord when an open- 

 ing was made. These prisms did not rest on the ground, but 

 were implanted in the mass of ice of which we have spoken. 

 At Bell Sound my friend M. Bravais observed two stages of 

 similar crystals placed one above the other, and separated by 

 a plane of ice. The lower stage, the least regular, was com- 

 posed of needle-like points in a state of great confusion.* The 

 ice of these prisms was light, and filled with air-bubbles ; its 

 colour often tinged with azure. These assemblages of ice- 

 crystals are found in planes perfectly horizontal, where the 

 water lodges and slowly imbibes the snow which covers the 

 soil. Their formation may be explained (comparing it to that 

 of crystallized salts allowed to remain for a length of time in 

 solution) by the successive juxtaposition of new particles of ice 

 every time the melted snow passes into a solid state, or by the 

 effects of the moisture being withdrawn. The ice-crystals 

 which enter into the composition of the lower parts of the 

 Helvetian glaciers, often attain the thickness of a nut, with a 

 length of fifty-four millimeters. t Kaemtz explains their ori- 

 gin in the same manner. % 



Moraines — Erratic blocks. The glaciers of Spitzbergen are 

 overlooked by nearly vertical mountains, whose summits are 

 composed of blocks of rock not intimately united with each 

 other, because the water produced by the melting of the snow 

 has separated them at the time of its congelation. Their sides 

 are for this reason covered with an immense quantity of debris. 



Between the lower extremity of the glacier and the moun- 



* Colonel Jackson has observed similar crystals on the Neva. See Tran- 

 sactions of the Koyal Geographical Society, vol. v. p. 19. 1335. 



f Hugi, 1. c p. 341. % Vorlesungen uber Metcorologie, p. 261. 1040. 



