land is sufficiently elevated, instead of rain falling, the moisture is condensed as snow. This accumulates on the mountain-sides, and instead of rushing impetuously downhill, slowly slides down, consolidating itself into ice in the process. When it reaches a depression, the moving ice forms a definite river of ice or glacier, which continues to flow down till it reaches a warmer level, when it melts and gives birth to an ordinary river, or
Fig. 3. Diagram showing a glacier reaching the sea, icebergs being calved from off it, and the morainic material being dropped, on the melting of the icebergs, into the mud on the bottom of the sea
it reaches the sea and pushes its nose out into the water. In the latter case blocks of ice are broken off by the waves, and these float off as icebergs. The top of the glacier, where the snow is consolidating, is surrounded by precipitous cliffs which are continually being riven by the frost, and blocks fall on to the névé or firn, as the consolidated snow is called, and are carried down in the moving mass, sinking deeper and deeper as they travel, till eventually they reach the bottom, where they accumulate as a ground moraine. This is dragged along the bottom of the glacier somewhat like the sand at the bottom of a river. The same takes place on the sides
