Abrasion geography – Help students understand the language of landscapes
Steve Brace explains how geography teachers can tell rich stories and unravel puzzling mysteries while teaching students about landscape features…
- by Steve Brace
Wherever we live, be it in one of the UK’s largest cities or a rural village, the location’s physical geography will inexorably influence our lives, shared environment, economy and communities.
Consequently, landscape features are the focus of much cutting-edge academic research – such as the explorations by Dr Chris Skinner into whether it’s ‘small and often’ or ‘large and infrequent’ change that does more to alter landscapes.
Such questions lead to the fascinating geomorphological conundrum of ‘Which came first – the valley or the river?’
“Landscape features are the focus of much cutting-edge academic research”
Whether it’s the inherent characteristics of coasts or drylands, or the features created by rivers and ice movements, these are the essential elements of pupils’ knowledge regarding physical geography.
Such knowledge is vital if we are to understand the impacts and interdependencies of humans on the environment – from our need to manage flood risks and coastal erosion, to how the retreat of glaciers will impact on our water supplies.
At the heart of all this are the processes of weathering and erosion. This is the means by which the Earth’s surface is broken down and changed, and how the resulting sediment is transported and subsequently deposited.
Typically, this will include teaching about weathering and erosion, and how the two differ.
Abrasion geography explanations
Weathering is the process by which rocks and minerals at the surface are broken down or dissolved ‘in-situ’. There are different types of weathering, which include:
- Physical, such as by freeze-thaw and exfoliation
- Biological, stemming from the impact of plants and animals
- Chemical, resulting from reactions with the atmosphere and/or water
Weathering breaks rocks down to create sediment which, when combined with organic materials, creates soil.
- Freeze a can of drink
This shows how the expansion of ice puts pressure on the can and deforms its shape. When water gets into the cracks of rocks it can break those rocks up. The resulting materials then fall downwards, forming the scree slopes often seen below escarpments.
- Place limestone in vinegar
By putting limestone (or concrete, which contains limestone) in vinegar, you can replicate the effects of acid rain. The acid in the vinegar reacts with the limestone to produce bubbles of CO2 which, over time, will weaken your rock sample. This same process – albeit over a very long period of time – is what shaped the famous limestone pavement found at Malham Cove in North Yorkshire.
- Sow seeds in cracks
Plant seeds between the cracks of paving slabs and wait to see how the plants’ growth may lead to heave and subsequently crack the slabs. In a similar vein, you can search a beach for rocks and pebbles with round holes bored into them. In the UK, these will typically be the result of a clam that bores into rock called a piddock.
Erosion differs from weathering in that erosion involves the transportation of materials via the movement and actions of water, wind or ice, with gravity providing a helping hand.
The processes of erosion typically covered in the geography classroom will include the following.
Types of erosion
The power of water crashing against a sea cliff can crack, splinter and ultimately remove rocks.
This refers to how the transportation of materials can lead to the surfaces they travel over becoming worn down. In abrasion geography you need to consider how, for example, glaciers grind any rocks frozen in its ice against underlying rock surfaces.
As a river transports rocks and pebbles downstream they will collide with each other, thus causing their edges to chip off and the pebbles themselves to become smaller and smoother.
The presence of water (particularly sea water) can dissolve certain materials. Cliffs composed of either chalk or limestone are especially vulnerable to this type of erosion.
There are many ways you can demonstrate these processes within a school setting:
- Demonstrate hydraulic action by using a power-hose to sweep away gravel
- Scrape a frozen tub of pebbles and ice across a paving slab to replicate the striations of glaciers
- You can even illustrate the impact of attrition on pupils’ bags of crisps or biscuits following a full day of fieldwork…
Landscape ‘nouns’ and ‘verbs’
As geography teachers, we can foreground the dynamism of these natural change processes by adopting an enquiry-based approach to exploring the why, how and where of the features they produce.
This, in turn, encourages students to use geographically-focused (and therefore relevant) questioning that draws on appropriate data, modelling and concepts. Examples of this might include:
- Why is there a road in the Norfolk village of Happisburgh that goes straight over a cliff?
- How did a WWII-era concrete pill box end up situated on the beach at Walton- on-the-Naze, Essex?
- At the turn of the 20th century, large erratic boulders made up of volcanic rock were discovered around Birmingham. They were subsequently found to have originally formed in the area we now know as North Wales. How did they manage to travel so far?
Beyond the UK
Looking beyond the UK when teaching landscapes and abrasion in geography, many pupils will also enjoy finding out about the features of unfamiliar landscapes. These might include desert yardangs or permafrost pingos.
That said, there’s value in using non-UK case studies to study ‘common’ geomorphological processes. After all, not every process occurring beyond the UK will be markedly different. Exploring such commonalities can provide useful context.
Indeed, pupils could get as much out of studying coastal processes locally – thanks to no UK school being more 70 miles from the sea – as they could from exploring their impact in other countries, such as the UAE or Ghana.
“Pupils could get as much out of studying coastal processes locally […] as they could from exploring their impact in other countries”
People sometimes describe geography as ‘the language of our landscapes’. By gaining a firm grasp of our landscape’s ‘nouns’ (the characteristics of its physical features) and ‘verbs’ (the dynamic processes that help create them), pupils can become much more fluent in their understanding of how landscapes are formed and change over time.
More abrasion geography resources
Aid students’ study of features and their underlying processes by using maps at different scales. A good example is this online case study of the erosion that’s affected the Holderness Coast, produced by Esri UK.
This resource explores the erosion of Happisburgh by the Digimap for Schools online mapping service.
The Royal Geographical Society, meanwhile, has a resource that shows the changing morphology of the River Thames along its 346km course from Thames Head to the sea. This draws on three Ordnance Survey map extracts.
Steve Brace is a former geography teacher. He’s now head of education at the Royal Geographical Society, working closely with the DfE, Ofsted and Ofqual. Follow him at @stevebracegeog