Glacial Systems - Characteristics and Formation of Warm and Cold Based Glaciers

The characteristics and formation of warm and cold based glaciers can be summarised as follows.

Warm based glaciers

These are known as temperate glaciers and are found in lower latitudes such as the Alps mountain range. Due to the lower latitude, the temperature around the glacier allows the ice to move relatively rapidly. The process of movement is largely through basal slippage.

Liquid meltwater plays a significant role in this process, provided by surface ice melting and being conveyed through the glacier via internal meltwater tunnels. In addition, as the glacier slides downslope it further increases the temperatures at the base due to friction and pressure. The subglacial ice layer can then melt and the resulting water will increase the rate of flow of the glacier by lubricating the contact between the lowest ice layers and the basal rock with meltwater. Where this process occurs some glaciers can move up to 3 metres per day. When the seasons change and there is less melting, the glacier will refreeze to the basal rock and months later, when the temperature warms up again, the glacier will pluck material away from the base and this will cause increased erosion as the glacier moves downhill once more.

Cold based glaciers:

These are found in higher latitudes and have less seasonal variation in temperature than those found in the lower latitudes. Meltwater is far less a presence. These glaciers still move but due to internal deformation/flow rather than basal slippage. They freeze to the bedrock and do not experience the same melting, but the role of gravity and pressure exerted by ice accumulation at the source causes the glacier to move. They may only move up to 2cm per day. The ice crystals within the glacier orientate themselves into the same direction as the ice slowly moves out from source regions.