Glaciers are formed when snow remains in the same place throughout the year, and enough builds up to turn it into ice. New layers of snow bury and compress the previous layers. This compression causes the snow to re-crystallise, forming grains similar in size to sugar. These grains gradually grow larger and the air-pockets among the grains get smaller, causing the snow to compact and increase in density. Crystals can reach several inches in length in older glaciers.
The fact that glaciers deform, added to their sheer weight and the force of gravity, causes glaciers to flow downhill.
Glaciers periodically retreat or advance, depending on the amount of snow they gain or lose. This movement takes a very long time, with more rapid movementh only being noticible over several months or years.
No comments:
Post a Comment