1847.] Glaciers of the Pindur and Kuphinee Rivers. 811 



being depressed by the action of sun and rain, while the protected parts 

 of the ice remains unmelted. The moraine is not a mound of debris, 

 as it appears at first sight, but an icy ridge, covered with rocks, some- 

 times with a breadth of some hundreds of feet, and raised from 50 to 

 80 feet above the general level of the ice. 



Glacier Tables. — Single blocks of stone lying on the ice, appear from 

 the same cause to raise themselves above the surrounding surface, upon 

 pedestals of ice ; — these are called glacier tables. 



Glacier Cones. — An accumulation of sand which sometimes forms in 

 holes in the ice, in like manner protects the surface beneath it, and by 

 a curious inversion of its shape forms a pyramid or glacier cone, some- 

 times 20 or 30 feet high and 80 or 100 feet in circumference. 



Baignoirs. — An operation strangely converse of this takes place, 

 when a small cavity forms in the ice, and becomes filled with water, 

 but with no considerable quantity of debritus. Water just freezing is 

 lighter than water at a temperature somewhat higher ; the water at 

 32° therefore floats on the surface of the other. When therefore the 

 surface of the water in the pool becomes heated by the sun's rays a 

 little above 32°, it immediately sinks, and by communicating its extra 

 heat to the bottom of the cavity, melts and deepens it, and being cool- 

 ed, is ready to rise again to the surface in its turn. 



Structure of ice. — The ice of which a glacier is composed, consists 

 of bands or laminae of blue compact ice, alternating with others of a 

 lighter color, not less perfect but filled with countless air bubbles. This 

 peculiar structure gives to a glacier all its extreme brittleness. The dif- 

 ference of hardness of the strata, causes the surface of the glacier in 

 many parts to appear striated with fine lines, and when groups of 

 harder bands occur, there are projecting ridges with grooves between 

 them, much resembling ruts in a muddy road. 



Direction of structural planes. — The direction of the bands or veins 

 is explained in fig. 9, which shows an imaginary section of a glacier. 

 The strata of ice lie like a succession of shells one within the other. 



Cause of veined structure. — The origin of the veined structure, seems 

 not be altogether satisfactorily explained ; but the direction of the 

 veins, and the form of the structural surfaces, is well accounted for by 

 Professor Forbes, as the effect of the different velocities of the different 

 parts of the ice, which as in running water is greatest in the centre 



5 N 



