The picture above is from s-cool (and the words below have been adapted from the information on the website). Clear picture showing where terminology is used against glaciers. A good pictorial source to help visual learners as well as a connection between where a process happens to what the process means.
FORMATION: Glaciers are made from prolonged periods of snowfall. The weight of snow compacts each flake so the air pores between no longer exist. Ice is created when this compaction causes some snow to become freezing water and further compaction creates ice.
TERMINOLOGY:
Ablation - This is when the ice melts at the lower end (snout) of the glacier, mostly during the summer months
Accumulation - When the glacier is built up due to compacted snow becoming ice
Calving - The splitting up of the glacier. This is how icebergs are formed if the glaciers lower end is at sea.
Glaciation - The formation of glaciers (compacted snow --> ice --> glacier)
Ice Sheets - Large masses of ice which cover a land surface e.g. Antarctica
Snout - the lower end of the glacier.
Valley Glaciers - Most common type of glacier. Valleys have already been carved out by a river and this type of glacier are found in all the main mountain ranges.
Abrasion - Just like with rivers, this is a form of erosion. With glaciers however, the rocks are embedded in the bottom of the glacier and as it moves, they erode away the bottom of the valley floor. This can create a polished or grooved expression in the valley floor and the grooves are known as striations.
Plucking - Main way erosion occurs. As the glacier moves, the ice melts slightly around large boulders and then re-freezes around them. When the glacier moves on, the boulders are ripped our of the ground and then become agents of abrasion.
Freeze-Thaw - Water enters a rock during the day and freezes are the temperature drops over night. The water then expands in side the rock, creating a pressure which eventually causes the rock to crack and split.
Glaciers carry huge amounts of material for long periods of time and these rocks are called moraine. Rock are usually carried after plucking form the valley floor. Frost shattered material from the valley sides is also carried called lateral moraine (carried at the sides of the glacier). When two glaciers meet, the two lateral moraines form a medial moraine which runs down the middle of a new, larger glacier.
Glaciers eventually start to melt as the move down a valley. Material is deposit as the glacier shrinks. The main depositional feature is terminal moraine. The glacier also creates recessional moraines and it will leave behind lateral, medial and ground moraines.
A glacier size depends on how much precipitation enters the glacial system. A general rule is glaciers at the moment are retreating due to global warming. The growth/retreat depends upon accumulation compared to the rate of ablation. This is the ice budget.
When the rate of accumulation is greater than the rate of ablation, the glacier will grow. This is called a positive regime.
When the rate of accumulation is less than the rate of ablation, the glacier will retreat. This is called a negative regime.
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