Liz Bonnin introduces a video clip examining how physical processes, including ice and glaciers, have shaped the landscape of the Yorkshire Dales.
Video
LIZ BONNIN: Hi, I’m Liz Bonnin. I’m looking into physical geography, but whereas a geologist might dig around some rock formations, I’ve been digging into the BBC’s vast archives to uncover programmes packed with inspiring information.
And this one has got almost everything. Spectacular views of the British countryside, locations that featured in the Harry Potter series, strange rock formations, rare plants, a place loads of you will recognise from school trips, fascinating facts and on top of that, they’ve thrown in comedian, Hugh Dennis, and wildlife presenter, Julia Bradbury, who get things started with a stroll atop a vast limestone patio in the Yorkshire Dales…
JULIA BRADBURY: Set foot on it, and it’s one weird place. Almost otherworldly.
Ooh, did you hear that?
I feel as though I’m walking along the spine of a dinosaur.
This spot is so weird, they filmed a scene from Harry Potter here. So how has such a mysterious place come to be?
This concoction of weirdly-shaped slabs and cracks would once have been a flat expanse of rock. But over the years, surface water has nibbled away at the limestone, leaving this incredible pattern.
The pieces of this limestone pavement, as it’s called, have old Yorkshire names.
The blocks are called clints. And the gaps are known as grikes.
But the most curious thing is what’s hidden down in the grikes. Meet Professor Cynthia Burek, a geo-conservationist, who’s fascinated by this unusual rocky habitat.
Limestone pavements are pretty mysterious places, aren’t they?
CYNTHIA BUREK: Yes, they are full of surprises and mysteries.
JULIA BRADBURY: Remarkably these cracks are teeming with plant life that’s extremely rare in Britain.
CYNTHIA BUREK: Down in the grikes we have a very shady, a very humid sort of environment. Microclimate, if you will. And we have shade-tolerant plants down there. Ferns…
JULIA BRADBURY: You’re making it sound quite nice.
CYNTHIA BUREK: It’s a bit narrow to get down there! It’s a real surprise for people when visitors come up here. They say, ‘Oh my goodness, look. Look at all these ferns. These hart’s tongue fern and the maidenhair spleenwort.
JULIA BRADBURY: Just lovely, lovely names!
CYNTHIA BUREK: Yes.
JULIA BRADBURY: But there’s a puzzle. These are plants you’d expect to see in shady woodland. Not here. How did they get here then? Well they’re a clue that not so long ago this all would have looked completely different. It was a thick forest.
CYNTHIA BUREK: So this would originally have been ancient woodland. The whole thing, but the only place we find the woodland now is down the grikes. This relic woodland flora which used to be everywhere. That’s what makes this landscape, this feature, so special.
JULIA BRADBURY: The woodland that once covered the uplands of Yorkshire were stripped back to bare limestone by our ancient ancestors and their grazing animals. It took thousands of years.
LIZ BONNIN: The limestone is the remains of tiny creatures and plants that died and sank to the bottom of a tropical sea, that covered the Yorkshire Dales, 330 million years ago. Now over millions of years, vast amounts of sea life got compressed into stone, creating a staggeringly thick bed of rock.
Later in the last ice age, glaciers swept right across Yorkshire, scouring the rock surface to leave those huge flat areas, and below that limestone pavement lies a place with its own dramatic story. A place that Hugh Dennis is particularly fond of, Malham Cove…
HUGH DENNIS: It’s a fantastic cliff. It’s about 200 feet I should think, top to bottom. It’s absolutely sheer. I think I must be feeling exactly what a spider feels like when it’s trapped at the bottom of a bath. They haven’t looked after it very well though, it could do with some limescale removing. Look at the staining on that.
Essentially you’re looking at one massive pile of dead coral and shellfish. And there’s the same amount again below ground. But wait and see what else happened here.
The sea bed that would turn into limestone began experiencing earthquakes. Over millions of years, a fault deep under the sea floor made part of it drop.
Eventually the sea dried up and there was desert. But the place was under constant change. In fact 300 million years of drama later, it was even covered in ice, which melted sending trillions of tons of water cascading over the drop in the ground.
It would have been like Yorkshire’s own Niagara Falls, sculpting and eroding Malham Cove into the place I love today.
LIZ BONNIN: Now that’s what I call an epic clip! Sometimes geography rocks!
Download/print a transcript of the video.
Julia Bradbury visits Malham Cove in the Yorkshire Dales to explain how the landscape has changed: the area was once ancient woodland but is now characterised by limestone paving.
The clip explains how the limestone pavement is formed, including the significance of ice and glaciers. It includes an animation of how the area was once underwater and how the seabed was impacted by tectonic movement, becoming desert, then being covered in ice, and eventually - million of years later - becoming the landscape that is seen today.
Teacher notes
Download/print the Teacher Notes for this episode (pdf).
Before watching the video
Locate Malham Cove in the UK and show images of the location to students. Ask students to write a locational description of Malham Cove.
Ask them to identify what they can see in the images and whether they can predict how this landscape was formed.
If you have pieces of limestone available for students to examine, this would be useful.
Introduce key terms such as:
Clints: A block forming part of a natural limestone pavement.
Grikes: A crevice or crack between clints.
Limestone pavement: A horizontal or gently sloping expanse of bare limestone which consists of large blocks called clints that are separated by grikes.
During the video
You may wish to stop at relevant points during this short film to pose questions and check understanding or wait until the end.
Useful questions might include:
- What type of rock is this landscape formed from?
- What are clints and grikes?
- What types of plants live in the grikes?
- What does this landscape used to look like?
- How has this landscape changed over time?
- What evidence is there that this location was once covered in water?
- What type of rock is limestone?
After watching
Discuss with students whether they were correct in their predictions of how the landscape was formed. Look closely at the clints and grikes to see whether students can identify the differences between them. Use online mapping to look closely at the limestone pavement at Malham Cove, ask students to describe the landscape.
Task students with creating a storyboard on how the landscape has changed over time from being an area covered in water to what it looks like today. This storyboard will help students to describe how the landscape was formed. The animation towards the end of the clip will help with this and can be paused at each stage to help break down the formation of this landscape.
Other examples of limestone pavements could be looked at such as the Burren in County Clare, Ireland, the Stora Alvaret in Öland, Sweden, the Great Northern Peninsula on Newfoundland, and the Désert de Platé in the French Alps. Students could make comparisons between Malham Cove and these landscapes.
Where next?
Examine igneous and metamorphic rocks – how they are similar and different to the sedimentary rocks we have examined in this film.
Look at a geology map of the UK, can igneous and metamorphic rocks be found in the UK? Is there a pattern to where they are found.
What characteristics do igneous, metamorphic and sedimentary rocks have? If samples of these rocks are available, hand these out to students. Can students classify these rocks based on the characteristics discussed?
Curriculum notes
This topic appears in Geography at KS3 (Geological processes) and KS4 / GCSE (UK Landscapes) in England, Wales and Northern Ireland and National 4/5 in Scotland.
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