Weathering and Cracks

23 January 2011 · 4 comments

in Science Outdoors, Social Subjects Outdoors, Urban

Change is happening all around us. Natural processes are constantly at work, shaping our landscape and some times playing havoc with our lives. Winter is a wonderful time for work on weathering and erosion, not least because it happens that little bit quicker. Certainly potholes seem to spring from nowhere on our roads after a few days of snow and ice.

Puddles form in natural dips – I wonder how they were formed? By the heating and cooling of the tarmac?
Earth processes are complex, yet many children find them interesting at a micro and macro level. As a young child, city walks and going round the shops with my parents was made interesting by cracks in the ground. If we stepped on a crack, a bear would come up out of the ground and GET US!

Water seeps into little holes and pockets. In the winter, freezing temperatures cause the water to freeze and expand. Over time, this causes cracks to appear.
Nice, orderly paving slabs were enjoyable to hop and skip over. But any natural cracks caused by weathering process added an extra challenge. Quite how the bear would appear and what he would actually do, was neither here nor there. Cracks were challenges of fun.

Plants cause cracks to grow too. It can be moss and lichen on a wall. A good example of weathering processes on vertical surfaces…

Or a tree seedling taking root…

Or roots just growing up, as well as under, the pavement…

Look at how this tree’s roots have uplifted the pavement! The power of biological weathering.
Some biological weathering is quite pretty. Gardeners may deliberately grow plants in cracks to soften and add variety to a stone feature, be it a wall or some crazy paving…

And sometime, the plants just decide that an abandoned lot is their for the taking. They become squatters!

I’m not sure if the weathering of paint is classed as a chemical or physical event. But this wall provided a beautiful example…

From a distance this just looks like a wall that needs a lick of paint or a mural added to it. But a good activity to help children hone in on the weathering processes is to take “near and far” shots with a camera. This can be displayed in a “Lift the Flap” format with a close up shot on the top of the card and the far away shot that explains the feature hidden underneath.

So when we look at this wall more closely what can you see?

A frightened cat?

An archipelago of islands?

And Australia!
Jenny, over at Let the Children Play had a blog post last year called Really Really Little Worlds. In this post, cracks have been used to create miniature worlds. As the photo below demonstrates, cracks add interest to our buildings. Challenging children to make cracks look artistic through creative photography is another trick to encourage close up observation as an alternative to “Gather round and look at this …” method of teaching!

I love the crack line here. It seems to blend into the doorway.
For real weathering enthusiasts it’s worth travelling to caves to see chemical processes at work…such as these stalactites.

©www.sesef.org.uk
But closer to home, good old-fashioned rusty fences show us an ugly face of chemical weathering.

©www.sesef.org.uk
If you are looking for more weathering activities to undertake with primary-aged children, then have a look at the Scottish Earth Science Education Forum website. There’s a Primary Earth Science Outdoors pack with lots of activities to undertake in the school grounds and neighbourhood. There’s also good scientific explanations of the processes in the context of the rock cycle.

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{ 4 comments… read them below or add one }

Pam January 23, 2011 at 20:40

The “frightened cat” was the best 🙂 I sometimes have to stop and think about how these small things can be viewed in this way! Too often I’m in too much of a hurry to reach my destination…but I know the kids would love to slow down and explore all these small things! I’m still working on slowing down!

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Juliet Robertson January 23, 2011 at 23:16

Yes! I liked the cat too!

I’ve often thought that we need a “slow education” movement with a little more focus on quality rather than quantity.

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Sherry and Donna January 24, 2011 at 11:12

You’re right Juliet it does look like Australia … albeit around the wrong way but Australia non the less!
BTW … I think our rhyme went something like … step on a crack, you’ll break your Mum’s back! When I’m walking and watching the pavement, I STILL avoid walking on the cracks! Go figure!!
Donna 🙂 🙂

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Juliet Robertson January 24, 2011 at 22:06

It is indeed more of a mirror image of Australia but me-oh-my so similar regardless.

It will be interesting to see if there’s anymore rhymes or activities that happen in other countries…

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