Magazine article Teaching Geography

Glacial Landforms: A Teaching Resource in Maps and GIS

Magazine article Teaching Geography

Glacial Landforms: A Teaching Resource in Maps and GIS

Article excerpt

Introduction

Geographical research means producing evidence that we hope makes our understanding 'less wrong' than previous versions of the 'truth'. The University of Sheffield's BRITICE project delivers landform evidence that tells us more about the huge, kilometres-thick ice sheet that once covered most of the British Isles.

The BRITICE map and GIS database of the glaciated landscape of the British Isles draw together over 170, 000 landforms from over one hundred years of field investigation, along with more recent mapping from satellite images and digital elevation models, both on- and offshore.

Thanks to this compilation, we now have an excellent picture of the distribution and pattern of Britain's glacial landforms. In our ongoing research, the pattern of retreat that we can interpret from these landforms acts as a sampling template, directing fieldwork to collect material (e.g. organics for radiocarbon dating) to date the timing and speed of ice retreat. This advances our knowledge of the ice sheet so we can assess how it responded to former climate change. The ultimate aim is to use our new knowledge to improve forecasting of the contribution of polar ice sheets to sea level rise in a warming world; here, however, we have given some examples of teaching activities to be used with the BRITICE map free poster and online resources (see below).

Drumlins and ice-flow direction

Use the online interactive BRITICE map to locate landform features. Take their latitude and longitude and find them on aerial photographs in Google Earth, to see what they look like and teach students how to identify them. The drumlins from the poster (Figure 3), for example, are good to search out: they can be found at -9.618 degrees (i.e. W) and 53.450 N. Textbooks usually say that the blunter, stoss ends of drumlins point upstream and the tapering ends point downstream. However, we have recently discovered that this is usually not the case, with most drumlins actually being symmetrical. Those with stoss and lee ends have a very slight tendency to be shaped as described in textbooks and indicating ice flow direction: however a near-equal number are shaped 'backwards', including those illustrated here. If you look on the map the ice-flow direction had to be away from central Ireland in an offshore direction: we can clearly see that the stoss (higher and wider) end of the drumlins is at the downstream end. Drumlins and their cousins, subglacial ribs (see map), were formed by interactions and shaping between the base of the ice sheet and the underlying soft sediments. Their significance and how they are formed is described in a 4-minute video on the GA website (https://www.geography.org.uk/Subglacial-bedforms-videocast).

Moraines and the pattern of ice sheet retreat

Moraines are ridges of sediment recording former ice margin positions with numerous examples across the map. Especially significant are those discovered in the last ten years on the seafloor. A useful exercise would be to get students to plot the course of retreat of the ice sheet, from its maximum extent through to its final demise. …

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