Definition Galore

After my last post, I was left feeling slightly encouraged by the start I had made; sure, it hadn't been extensive on the knowledge front but it was a start. However, as I started to move on, looking at how glaciers form and the types of glacier I began to feel that I was missing something. As I continued to look through websites and diagrams I realised abruptly what it was that I felt I needed in this study; key terms. I therefore set about creating a table filled with terms that I felt would be important to contribute to my knowledge:

Key Term	Definition
Ablation	The process by which ice is lost from a glacial surface through the processes of melting, sublimation or the calving of icebergs
Areal Scouring	The erosion of lowland bedrock areas by an ice sheet (usually large scale)
Arête	A sharp ridge of rock formed as a result of glacial erosion occurring from both sides
Basal Ice Layer	The layer of ice that is found at the base of a glacier. It is strongly layered and can include a variable amount of debris
Basal Sliding	The movement (sliding) of a glacier over bedrock. This is often aided by the effect of meltwater
Bergschrund	A crevasse which forms as a result of active glacier ice moving away from ice adhering to the mountainside
Boulder Clay	Unstratified clay deposited by a glacier and consisting of a variety of boulders. Often referred to as 'till'
Cirque	An armchair shaped hollow which has formed as a result of glacial erosion high on a mountain side with steep sides and back wall. Also known as a 'corrie' or a 'cwm'
Crag-and-Tail	A glacially eroded rocky hill. Produced as ice moved over a hard layer of rock which protected softer rock behind it. This formed an outcrop with a steep side facing ice flow and a gentle slope on the down stream side
Crevasse	Vertical crack in the glacial ice. May be formed as a result of the glacier making a sharp turn or moving over undulations in the glacier bed. Can vary in size and depth
Drumlin	Elongated, oval hill composed of glacial debris. The long axis runs parallel to the flow of the original glacier with the steeper end facing in the direction of the ice flow.
Englacial Conduit	A channel formed within the glacier which carries waters towards the glacier bed or margins
Erratic	Boulders, or large blocks of bedrock that has been, or is being, transported away from its source by a glacier and deposited when the ice melts
Esker	A long, narrow ride of sand and gravel deposited by a stream in a subglacial tunnel
Firn	Dense old snow (in between the stages of snow and glacial ice) that has a sugary texture and in which the crystals are partly joined together
Hanging Valley	A tributary valley with the floor at a higher relief than the main channel into which it flows. Often marked by a waterfall
Ice Sheet	A large mass of snow and ice of a considerable thickness and covers an area of more than 50,000km²
Little Ice Age	Period of time which led to the expansion of valley and cirque glaciers world wide. Maximum extent occurring in 1700-1850 AD in many temperate regions
Moraine	Distinct ridges and mounds of debris laid down by a glacier or pushed up by it. Many different types
Lateral Moraine	Debris deposited along the side of a glacier
Medial Moraine	Band of debris along the centre of a glacier where two streams of ice merge
Terminal Moraine	Ridge running across a valley which represents the maximum advance of a glacier
Ground Moraine	Debris deposited on valley floor. Found where glacial ice meets rock at the bottom of the glacier
Push Moraine	Assortment of debris that has been pushed up by a glacier during an advance. Can range from a few metres to tens of metres in height.
Moulin	Roughly circular, almost vertical hole within the glacier through which water can enter from the surface down the glacier bed
Outwash plain	Spread of debris deposited by meltwater streams coming from a glacier
Roche Moutonée	Rocky hillock with a gently inclined, smooth up-valley facing slope and a steep, rough down-valley facing slope
Striations	Scratch marks found on rocks as a result of the abrasive effect of debris rich ice sliding over bedrock
Tarn	Small lake occupying a hollow eroded by ice; common in cirques
Truncated Spur	River spur that has been cut off by glaciation of a former river valley. Characterised by a very steep cliff

A  lot of these words are quite long and complicated, especially words taken from the French and German language such as Bergschrund and Rouche Moutonee and so it may take a while for students (as well as myself) to fully get to grips with these terms. Showing students pictures alongside these definitions may also help with the learning of these terms as it is sometimes easier for students to be able to see and apply their knowledge rather than purely being told. After composing this table, I feel that I have furthered my knowledge purely by just understanding the key terms that I keep coming across. As well as this, I also felt that I may have even be halfway to composing a potential lesson resource! Handing out this table, or one somewhat similar, in lesson and getting students to either stick it in their book for reference or for an activity in which students would be handed the definitions and key terms separately and then asked to put the correct term and definition together. This could help to see how student have progressed with the topic as well as helping them further their own knowledge on the subject.


Finally, I also looked at how glaciers are formed. After trawling through many websites, images and youtube videos, I found that many of the diagrams were slightly misleading and confusing and so I went back to the National Snow and Ice Data Centre website which I felt gave the most succinct information that I needed. Essentially, glaciers form when snow remains in the same area every year and accumulates to the point where it eventually transforms into ice. As this process continues, the new snow that has accumulated buries and compresses the previous layers. This results in the snow re-crystallizing and becoming similar to grains of sugar. Over time, these grans become much larger in size and the air pockets between the grains becomes smaller causing an increase in density and eventually, over roughly two winters the snow turns into firn (refer to table above for definition). As the process of accumulation and compression occurs over many years, grain sizes become larger and larger and thus, a glacier is formed.

This, I feel, begins to explain not only how a glacier is formed but a few key terms which could be helpful for students to see how all these key terms fit together within the topic.


Overall, the creation of a key term table at the beginning of the topic could be helpful for pupils to refer back to throughout the learning of the subject as a helpful referencing guide as well as an aid for learning and revision. Creating activities around the table could also help to make lessons more interesting and engaging, assisted with pictures for an aided aid. 
The next aim will be to look at the different types of glacier that can be found - something images will be very helpful for!

Websites used:
http://www.swisseduc.ch/glaciers/
http://nsidc.org/cryosphere/glaciers/questions/formed.html
http://www.geography-site.co.uk/pages/revision/ice.html