Glaciers: mountains of ice

Abstract

The glaciers of Africa are limited to three specific geographic locations; two volcanoes (Mount Kenya and Kilimanjaro) and one mountain group (the Ruwenzori). Glaciers begin to form when snow remains in the same area year-round, where enough snow accumulates to transform into ice. Each year, new layers of snow bury and compress the various layers. This compression forces the snow to re-crystallize, forming grains similar in size and shape to grains of sugar. Gradually, the grains grow larger and the air pockets between the grains get smaller, causing the snow to slowly compact and increase in density. After about two winters, the snow turns into firn – an intermediate state between snow and glacier ice. At this point, it is about half as dense as water. Over time, larger ice crystals become so compressed that any air pockets between them are very tiny.

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