Rock Types at Great Heights

One of the best ways to investigate the landscape of Britain

is through walking and climbing.

In this programme, we're going to challenge three pairs

of young people, each climbing different rock formations,

to investigate the geological and geographical processes

which have taken place.

Today, we're in the Snowdonia National Park, Wales.

We'll be climbing the Cwm Idwal Slabs.

These magnificent rocks were folded by tectonic activity

around 400 million years ago.

The movement of the Earth's plates crumpled and squashed the rock

into new shapes.

Volcanic eruptions, followed by glacial activity in the last ice age

also helped to carve and shape the landscape.

'I'm Dr Tom Challands. I'm a geologist and I'm also a climber.'

I'm here today to challenge two young climbers and geologists

to investigate the type of geological processes

that contributed to forming these big cliffs

that we see here behind us.

Over 450 million years ago, this was the site

of a massive violent pyroclastic eruption,

the same type of activity seen more recently in Krakatoa.

The area is important historically, and not just for climbing.

It's here, 170 years ago, Charles Darwin tested the early theories

of glaciation and glacial erosion,

applying what he'd learnt from his earlier travels in the Alps.

Our first climber is Alex, he's 15 and from Essex.

I study Geography and Geology at GCSE level

and I enjoy the field work in both subjects.

I really love climbing because I find it exhilarating

and it challenges me, puts all my skills to the test.

Maddie is also 15 and from Birmingham.

I don't really have that many expectations,

just have fun and try and learn as much as possible.

'Indoors, it's set out for you.'

'I'm going to have to think about what to do, where to put my feet.'

It's raining, but that's not going to hinder me.

I'm going to power through.

The weather's not very good.

It's looking slightly tricky and slippy underfoot.

They're going to have quite a big challenge ahead.

It's still raining, but I'm going to set you the challenge still

because I know you're made of stern stuff and that you're keen

and you're eager to get on with it.

So here's today's challenge.

We've given Maddie and Alex 20 minutes

to plan their tactics before climbing.

To help, they've been given this box of tricks.

They can choose four from this range of geological equipment.

Some will be really useful on this climb - others will be useless.

They don't know this area or the route they'll climb.

They'll have to use these items and their knowledge of geography

and geology to find as many clues as possible

to unlock this rock's history.

It's good they're looking at the bigger picture

and not just what they think they'll encounter immediately on the climb.

This is how to choose the best equipment.

That looks like an anticline because it's bedded diagonally, like that,

pointing upwards. You can see the nice beds on top of each other.

We've chosen two compasses with hand lens on the end,

a grain size card which will help us measure the grain size,

and a note book to write everything down.

Obviously, you can see this is a U-shaped valley

so there must have been a glacier at one point here,

and there are truncated spurs.

There's a tarn which also indicates there's a glacier there

-because it's a melted glacial lake.

-Yep.

'They've jumped to a few conclusions about glacial activity

'in the area without any real evidence, but...'

I've got a lot of hope for them.

They're both very intelligent kids, they're really on the ball and from

what I've been hearing them discuss they're going on the right lines.

We chose a compass because it helps us measure the dip and strike

of the rocks, and also it's got a hand lens on it

which is helpful for telling grain size.

We've picked a grain size card,

because as well as telling grain size, which helps us identify rocks,

it also tells us how to measure sorting of grains,

roundness of grains, and as well as that, percentage area of coverage

of the rock that the grain has.

Which is all helpful in helping us identify rocks.

I wanted to ask Dr Tom how to measure dip and strike again,

because I wasn't actually sure how to measure it.

I have a rough idea, but I want to be sure before I go up the cliff.

We're measuring the dip of the rock

because it lets us know if it's been tilted or folded.

It's a real clue to the tectonic history

and it'll help with the challenge.

First of all the dip of a bed of rock is the angle at which it tilts,

the maximum angle that it tilts,

and we can easily find the maximum angle of tilting

simply by getting some water, and we're not short of that today.

If we drip a little bit on the rock,

the direction the water will travel in is the direction of maximum dip.

This compass also has a small dial

on the inside of the actual circular part, here.

What we want to do is align the compass

so East and West are lined up with the arrow at this end.

The dial here which goes from zero degrees at the bottom to 90 degrees

at the side is horizontal when we have the compass in this position.

You're then going to place it

on the piece of rock you want to measure the dip of,

and what's very important is to make sure it's a solid piece of bedrock,

not a loose boulder because a loose boulder will give a false reading.

We're going to move the compass clinometer around

until this arrow here stops moving back and forth.

It seems to be pretty still there, and it's reading 21 degrees.

Then what we do is use a pencil,

draw along the rock along the edge of the compass.

It's very important to use a pencil or a piece of chalk,

something that will wash away.

We don't want to scratch or damage the rock.

We'll take our compass,

and now, lining our compass up with that line we've just made,

we then rotate the bezel here, the dial,

until the red arrow in the middle

lines up with the red floating arrow,

and the number that reads at the top of the compass clinometer here,

and in this case it's 268 degrees, is the direction of dip.

Here we have a dip of 21 degrees,

we have a dip direction of 268 degrees

and the strike which goes two ways is 268 minus 90 or plus 90 degrees.

So we have our strike, dip and dip direction.

That's much clearer, definitely.

Brilliant, so now you've chosen your piece of equipment,

you know what measurements you're going to make, how to make them,

I think we should go and do the climb and collect some data.

How does that sound?

Sounds good.

Right. Let's go and do that, then.

'This field study is also a climbing challenge,

'so if you don't know what you're doing, it has its risks.'

Got all the gear?

'These climbs shouldn't be undertaken without expert help.'

The geology is really helping the climb.

This huge crack, which could be a joint or a fault, is really useful,

and is revealing some early clues.

Maddie, there's a little line of, like, quartz in the middle.

The crack here is the defining feature of this rock face.

How it was formed will help them with the challenge.

They just need to look for evidence which will tell them if it's a joint or a fault.

Looking into the depths of the crack, there don't appear to be

any broken up bits of bits of rock like we might expect from a fault.

Those broken up bits of rock are actually fault breccia.

If we can't see that fault breccia in here,

that might indicate that it's not a fault but rather a joint.

In this crack, there's a massive lump of quartz.

If that has significance, I'm not sure.

It's great to see Alex and Maddie noticing the changes in the rock

as they climb, and looking for solid areas to take their readings.

Different strike readings.

They've obviously taken on board the mini briefing on using the

-compass clinometer and are making frequent measurements as they climb.

-OK.

It might be simple, but that notebook is vital,

or they'll never remember their results.

Two or more set of cracks can reveal how the order of events happened

in the rock but what they can't reveal is how long it took.

You need to gather other evidence for that.

So I'm a little bit further up the climb now

and I've found another set of cross cutting joints,

cutting across the main fracture here,

but what else we have is vegetation growing in this fracture.

This is an example of biological in situ weathering.

Look at that!

This looks like this parent rock right here,

this, obviously, is some quartz,

which begs the question how it got there.

Little parts of quartz, some bigger, some smaller,

some really small ones, a yellower one and a more grey one,

which indicates some type of weathering, possibly,

or something else in the rock.

These loose bits of quartz Alex has found washed in here

are great examples of weathering and erosion.

What we have here on the surface of the slab are some quartz crystals.

A quartz bedding plain, almost.

This is actually a quartz injection,

that's a vein that's injected along the bedding plane itself.

This is the final measurement of the climb.

They've taken one at the base, one in the middle

and now we're at the top of the climb, just taking one more.

So from this vantage point in the climb

we have a really good view of the head of Cwm Idwal,

the large synform right at the heart of the Cwm.

It's the curves you can make out in front of me on the rock face.

We can also make out a large periglacial landslide below it.

There's a clue to the glacial past of this area in the name

"Cwm", as in Cwm Idwal.

It's the welsh word for corrie,

and a corrie is a glaciated mountain valley.

Further down at the foot of the slabs we have roche moutonnees.

A bit further down by Cwm Idwal

there are also some very, very clear moraines.

So we're starting to get a good picture

of the geology and geomorphology.

OK, guys, I think it's time we got down now.

Hands off the rock. In back, now.

That's it. That's it. Just like being low down on the climbing wall.

Maddie and Alex abseil back to base.

This'll give them one last chance to look at the structure

and spot any last minute bits of evidence.

I'm quite confident that they've got a good idea

of what's happened here in Cwm Idwal.

We're looking at the bigger picture.

They looked at it before they went up the route,

they looked at it when they got to the top of the route

and they also made some small-scale observations and measurements as well.

So, you've seen what I think. Now they've got 20 minutes

to pull together their evidence and see if they can answer the question.

So, we asked them to describe how the slabs have been affected by the

tectonic history of this place and what caused the subsequent erosion?

We found quite a lot of evidence actually,

from erosion to different rock types and minerals.

And I think all of it will definitely help us with our question.

We just need to sit down together and confer and relay back

our different information and then try and find out something concrete

that we can put forward for the question.

There's quite a lot of quartz up the joint that we found.

That might be from a hydrothermal ore vein which is tectonics

because of the magma that's come up in an igneous intrusion

somewhere around here.

That's heated rainwater that's percolated through the ground

and as that rain water comes up, it collects minerals such as quartz.

We found some trachopyrate as well,

which is another mineral that we would find.

Obviously it carried it up and as it went up it cooled,

and solidified in these joints.

Obviously the tectonic activity

has created these quartz hydrothermal ore veins.

The compass clinometer helped us measure

three different dip and strike angles and the direction of dip.

It increased in steepness as we went up.

At the beginning it was 42, and then mid-point it was 52,

and at the top the final reading was 60.

It helps us see how the rock's been affected as it goes up,

for example, if it's steeper at the top, less steep at the bottom.

This is a great point to spot,

because we were climbing on the limb of this fold we can see here.

I think the main erosive features are definitely the truncated spurs

-that you can see, and the moraine, you can see it everywhere.

-OK.

-And the main structural features?

-The quartz veins.

The way the joints are facing as well

and all the other evidence for erosion with smooth rock.

So the structure has contributed towards the erosion and weathering.

That's a lot of good interpretations based on your observations,

and that's exactly what geologists do.

So, today's challenge was all about the effects

of tectonic activity and glacial erosion.

Let's look in detail at what actually happened here.

We start with the deposition of volcanic rocks, tuffs and lavas

during the subduction of the Laurentian plate

beneath Avalonia and Baltica.

Scotland, England and Wales are united for the first time.

Leading to the Caledonian mountain building period event.

Layers of rock are bent under extreme pressure,

and hot, briny hydrothermal fluids formed during the collision

deposit minerals such as quartz inside the newly-formed cracks.

Until the ice age.

But this landscape is for ever

changing due to further erosion

because of melt water and vegetation

as well as wind and rain.

The geology challenge was pretty hard, but I did learn from it.

I was quite scared to do the climb, but actually when I did it,

it was really fun.

I'll probably take away learning not to be afraid to try new things

and even if something's wrong, always just say it,

because there's a chance that it might include something

that could be developed on.

Today's actually taught me definitely a lot more about geography.

Some of the things we found, like the truncated spurs,

I did not know about them.

Without Maddie, I would have completely missed all that.

I would definitely do it again if I could.

So that's it's for today here on Idwal slabs.

It's been an adventurous day for climbing, for geology,

and most certainly adventurous weather.

Still to come, we'll look at a rock face affected by human activity...

..and climbing in an area which was formed

as the result of a massive river delta.

Castle Inn is a redundant limestone quarry in Conwy, North Wales.

Although no longer providing limestone to the building industry,

the past quarrying and the way the rock weathers

means it's still used by us today.

Castle Inn forms part of the local leisure industry

as a climbing wall and nature reserve.

I'm Dr Tom Challands and I'm here today

to challenge two keen young climbers

and geologists to answer a couple of questions

about the rock face we have behind us.

The rock face we're going to climb today is made of limestone,

which is particularly interesting

as it's got several different types of structures on it

This quarry is now a nature reserve.

I hope the young climbers we have with us

are going to spot some things about the way this rock was formed,

but also about the geography and the way this old limestone quarry

has been affected by human use, but also by nature.

I'm Tom and I'm 14 from Stockport.

My hobby is rock climbing.

I'm here because I want to learn a lot about the rocks.

My name's Laurie. I'm 14 years old

and I live in Derbyshire.

I love being outdoors on field trips, yeah.

Outdoors all the time.

You're not stuck in the classroom looking at the computer.

Well, I know that Tom and Laurie are both really good climbers

and they seem very keen to get on with the job.

I'm interested to see what they make of the challenges because we've got two things to ask them.

We've got to ask them a lot about geography

and also we are going to ask a little bit about the geology,

because the two things really are mixed together.

-So here we are in the quarry, and I'm going to set you the challenge. Are you ready?

-Yep.

So here it is written down for you to look over and think about,

and what we have in this suitcase here

is some equipment that will help you make observations,

take measurements and collect the type of data that you need.

So you've now got 20 minutes to go away,

choose four pieces of equipment from here, put your heads together,

make a plan, and then we'll get on with climbing the route,

going and collecting your data.

They can choose four from a range of items in this case.

Some will be useful for this climb, others will be no use at all.

They don't know this area or the route they're going to climb.

They'll have to find as many clues as possible

to unlock this rock's history.

So part of the question we've asked Tom and Laurie today

centres around the principal of uniformitarianism.

Using the present as the key to the past.

It's hard to believe, looking at today's weather, but this rock

was created in a climate we'd now expect to find in the Bahamas.

Is that hydrochloric acid?

Oh, yeah, we used it in science.

We were dripping it onto the limestone.

So we can test if the rocks are actually limestone.

Definitely hydrochloric.

We've got the geological timescale which lets us know

in the rocks there's many fossils,

and we get to know how old the rock is, and my prediction is

the higher up it'll get, the newer the fossils will be.

Also, I've got a magnifying glass,

to work out the fossils in the rock and we'll be able to work them out

and compare them to this sheet.

As well as that, our final item is the micro fossils sheet.

We'll be able to find out what the fossils are called.

I'm quite confident because I think we've chosen the right things,

but we'll see.

They might not be able to learn much about how this rock was formed

just using a geological time scale and with the microfossil card,

well, they're microfossils.

They'd really need a microscope to see them.

However, the hand lens will be very useful for looking at some larger fossils they might see

and finally the hydrochloric acid will be really useful

to find out whether or not this is limestone.

Laurie, Tom, one of the things you wanted to do

before you went climbing was test whether or not

this rock is limestone.

So, to do that, we have some hydrochloric acid here.

It's very dilute, but we don't want to be taking hydrochloric acid with us,

and we don't want to be knocking pieces of rock off, so let's just put this down on the floor.

Get this over our eyes.

What are you expecting to see?

-I think it bubbles a bit.

-Yeah.

OK, let's see what we get.

-There we go. It's bubbling pretty vigorously.

-Yeah.

Those bubbles are carbon dioxide that are being released,

as the hydrochloric acid reacts with the calcium carbonate

in the limestone,

and given that there also seems to be some other objects in this rock,

I'd say we have a positive limestone identification.

We're going to go up the rock face now,

and we're going to be able to look at how the rock is formed.

We might be able to see some layers

if it is sedimentary rock like we think,

and maybe we can see whereabouts the rock is as we get higher up

and we'll be out of the shade of the trees.

I'm really looking forward to going up there and just checking,

checking out the rock and hopefully finding out some good clues

to help us with our investigation.

Tom and Laurie's field study challenge has its risks,

if you don't know what you're doing.

It shouldn't be undertaken without expert help.

It's the natural bedding planes, along with the fractures and joints

in the rock that's helping them on the route.

Some produce big climbing holds, but smaller edges formed where

the rock has simply broken off, making for trickier climbing.

Lots of this stuff.

Corally, isn't it, here. It gets a bit darker over here.

Here, on the face of the limestone surface, we have this white,

crusty deposit, and this is a tufa deposit.

It's formed by the reprecipitation of dissolved limestone.

Smooth. Not much friction.

This is because limestone is a soft rock,

made from the relatively unresistant mineral calcite.

It polishes easily to give the smooth surface Tom has spotted.

It's like a layer of rock, like a thin strip going all around here.

Tom's just seen a bedding plane picked out by a thin layer of mud.

Another really good climbing hold on this limestone rock face.

It's quite polished from where climbers have been on it.

That could be how people use the rocks now.

So here we see further interaction of humans with the rock face.

It's a bolt used for sport climbing, and like we see at Cwm Idwal,

it's good example of how humans start to erode away the rock

as they climb up it.

There's a good view all the way over there,

and we're not quite in the bottom of the valley but nearly.

Wow, these are weird, here. It's like it's run down or melted.

They're kind of all dripping down, almost like stalactites.

So here we have a beautiful example of tufa again, but this time,

rather than the tufa flowing over the rock face, it's been

dripping from a single point to produce these beautiful,

beautiful stalactites that have a really nice ring to them as well.

Fossils found here could reveal what's known as

an environment of deposition, and if they're the right type

it'll point to deposition in warm, shallow, tropical seas.

Oh, yeah, look. I've found a fossil.

Let's see. I've got this thing, I'll have a look.

So here now near the top of the climb we can see some nice shells

fossilised into the rock, and these are brachiopods,

filter feeding organisms, but they're not very complete.

They're all broken up and fragmented,

and that tells us that they were not deposited here,

they didn't live here, but they were broken up,

they were transported from a calm, coral sea environment

and moved into this position.

And from here we get a really good view of the extent of this quarry.

Let's look at it on this.

You think it could be...?

I can't really see it on there, it's like a polo mint.

Yeah, it's got like a...

There's these ones as well.

Unfortunately this is a microfossils card, so it can't help them at all.

You would need a much more powerful microscope than their hand lens

to pick out any microfossils in this rock face.

Could they be burrows?

Maybe.

Right here at the top of the limestone quarry cliff face

we can see that the limestone that's been exposed to the surface

the longest has started to form this nice, wobbly, blobby castified

surface with these rivulets here, and this is formed from

the dissolution of limestone by weak carbonic acid.

Whereabouts do you want to stop?

Er, about here.

About there. OK, got you there.

What makes you think it's coral that's in front of you?

It's kind of similar to what you find at the seaside.

Okie-doke.

It's formed under water, isn't it, Limestone, I think.

They're a bit like barnacles, really.

So if we lower you down slowly, have a good look at the rock close up

to see if you can see any really small fossils.

OK.

'Now, sometimes comparing what you see today

'and applying it to the past can lead you astray.'

'What they're calling barnacles is actually tufa.'

So those little fossils that you're looking at in front of you,

are they the round polo mints like the ones that we saw

in the hydrochloric acid test, or are they long, sort of elongate?

These ones are a bit longer.

Yeah.

They're joined together, then?

This one's like the polo mint one.

There, yeah.

Like little discs stacked upon each other.

It was really good, it was quite easy climbing,

but it meant I could look at the rocks and look at the fossils in the rocks.

It was quite hard to look for the kind of things like the fossils,

but once you got used to it, Laurie was quite good at it as well,

and we were looking through them and we found out the names

of a couple, so we will be able to see how old the fossils were.

So you've seen what I think.

With the climb over, Tom and Laurie have 20 minutes to look at

what they've discovered and to think about the question.

What climate and conditions this rock was formed under,

and since then, what processes have affected it?

It's been used by humans, obviously, by bolting the routes.

Yeah, there were lots of bolts.

-So rock climbing. It's also been quarried, hasn't it?

-Yeah.

Not sure what for, but...

Maybe to get the calcite out.

Yeah.

What else do you think?

Well, there's lots of plants growing in it,

-and it's a nature reserve, I think, now.

-Yeah.

So people are looking after it.

We found fossils,

and maybe they suggest that animals were living around here.

We think it's formed in layers.

Yeah.

And different textures of the rock and colour.

-Is that all our evidence?

-Yeah.

So, Tom, Laurie, can you just summarise the evidence

that you came across, and what interpretations you've made?

Well, obviously the rock's been bolted by humans to climb on,

and as well as that, something's been quarried out of these rocks.

What do you think has been quarried, then?

I'm not sure. Maybe some kind of fossil or crystal?

So limestone is used a lot in industry,

and also a lot of the houses around here are made of limestone

-themselves, so it could have been used as a natural resource in that way.

-Yeah.

So, Laurie, the geology part of it.

So, first of all, using present day knowledge

about where rocks are formed, what evidence did you go

and then look for to interpret how this rock may have been formed?

After we found out that the rock was limestone,

we knew that it was a sedimentary rock,

and so we know that they are built up by clay and bits of mud

all going on top of each other, and eventually kind of fossilising.

So did the tests that we did with the hydrochloric acid

tell us that it was a specific type of sedimentary rock?

We knew that it was limestone then.

So that's what it told us, that it was limestone. Brilliant.

As we were climbing up, we could see the layers of where these

different types of mud and clay had all gone on top of each other.

And amongst the mud, there was also some, did you say fossils?

Yeah, we found lots of fossils.

They were round and looked a bit like polo mints.

OK, so the fossils didn't seem to be whole,

they were all broken up and mixed up, OK.

When you were climbing,

you came across some quite strange structures.

Yeah, it was a bit like going into a cave.

-There were these, like, stalactites.

-OK.

We were wondering whether maybe they were formed from water

dripping down the rocks, which is how stalactites are formed.

We wondered whether it was maybe underwater at some point.

Can you think of any modern-day environment

where you might have, sort of, limey mud,

where organisms might be living on the bottom of the sea.

Anywhere around the world that sounds familiar to that?

We did think of maybe the coral reef in Australia.

Right, OK.

Well done, guys. I think you've done really well.

'Well, today's challenge was all about the conditions

'under which this rock was formed

'and the subsequent processes that have affected it.'

Our shelly mud, now a limestone, is exposed near the earth's surface.

Tom and Laurie both weren't really geologists,

they've come from geography,

and as a team, that meant that they really had to look at the evidence

and find things together, so they were both in the same boat there.

I think working as a team was quite useful, seeing as we could put

both our thoughts together and combine them into something better.

I think it did pay off, being confident.

We were positive about things, and it went well for us.

What they did was they really started to relate to each other,

they started to share ideas and share their evidence.

I think it's very important to gather lots of evidence

before you come to the final conclusion.

If I got the opportunity to do this again, I'd definitely do this.

I had a really good time.

That's it's from Castle Inn,

but still to come, we'll be moving to Staffordshire

and climbing in an area which owes it's formation to river action.

Today the gritty sandstone Roaches in Staffordshire

form part of the Peak District's National Park.

Thanks to the eerie and stunning rock formations,

it's popular with tourists who visit for walking and climbing.

I'm Dr Tom Challands and I'm here today at the Roaches

to challenge two young enthusiastic climbers and geologists,

by posing a geological question to them

that they are going to have to answer

by climbing up the cliff face here and collecting evidence.

I'm Anna. I am 16 years old

and I study GCSE geology.

I like, sort of, finding out how things have formed

and how they evolve, almost, over the years.

I'm Jonny. I'm 15 and I live in Cornwall.

I enjoy geology because I enjoy working in the field

and collecting data and evidence.

Here at the Roaches,

the sand that formed these rocks we have here around us today,

was deposited in an ancient river delta about 300 million years ago.

If you have trouble imagining what this may be like,

look at these pictures of a modern-day braided river.

And what's happened since is that these rocks were consolidated

and compacted to form hard sediment.

The hard rock that we are going to climb on today

is that soft rock above and below have been weathered away

to leave a nice, big gritstone escarpment.

What's going to be very difficult for the children today

is to make that relation between a modern environment

and the ancient environment here.

That's a key part of geology.

It's about uniformitarianism, the present is the key to the past.

So by reflecting on modern depositional environments

like the Mississippi Delta,

hopefully they will be able to recognise some of those structures

and some of those meandering river forms here in the Roaches rock.

Jonny, Anna. We're sitting here at the bottom of a rather misty,

wet Roaches crag and it's about time we gave you a challenge to do,

so we can get moving and get your brains ticking.

Your challenge today is this.

There's some paper there that you can make notes on,

and also choose four pieces of equipment

from our geological kit box here.

Choose wisely and choose them

according to the challenge we have just set.

They can choose four from this range of geological equipment.

Some will be really useful on this climb - others will be useless.

They don't know this area or the route they're going to climb.

They'll have to find as many clues as possible

to unlock the rock's history.

I think it's a good challenge and I'm looking forward

to going climbing and collecting some evidence.

This might be useful, for grain sizes.

Oh, OK yeah.

We chose the hand lens so that we can look at the different grain sizes

in more detail so we can see sort of where they are placed,

which should help us

I also chose the Geological Time Scale because that means that

we might be able to date round about when it was formed

which might help us with our investigation.

The other thing we chose was a compass clinometer to work out

the angle of the rocks.

We think it's going to go OK

if we can find the right evidence to prove our investigation.

Jonny and Anna are both doing their GCSE geology

and know how important it is to look at the grain size

and the grain shape of sedimentary rocks.

So they've got a grain size card and a hand lens

to look at the grains as well, and that's brilliant.

What they haven't taken is the notebook.

They may spot all of these things,

but they won't be able to write down their observations.

It's very important to record your data.

They've also got the compass clinometer and that will allow them

to measure the direction of current flow, in beds and foresets,

cross-bedding that they might observe in the rocks.

So the weather's clearing up now, the rock's still a bit greasy,

hopefully if the sun does come out a bit

and it will be just enough to dry off.

We're about to start climbing up the rock face,

to find some evidence to see whether the sediments were deposited

and which way up the rocks are.

If you don't know what you're doing,

Anna and Jonny's field study challenge has its risks.

It shouldn't be undertaken without expert help.

I'm looking forward to it. I think it's going to be a good challenge.

Here you can start taking measurements almost immediately,

even before you start the climb.

These large, rounded rocks Jonny is clambering over

are ideal to take the first reading.

I've not got a pen.

Got the chalk?

It's really important to use either chalk or a pencil

when taking dip and strike measurements.

It washes away, so there's no damage to the rock.

I think the strike is measured at about 30.

-Does that sound about right?

-Yeah, that sounds right.

Jonny's making good use of the way the rock is eroded

to help him climb.

These cracks, smooth ledges and the coarse, gritty rock all help.

One thing that Anna and Jonny may have found difficult is to tell

the difference between bedding and foresets of cross beds.

Here we can see clearly the difference.

The bedding plane is at a shallower angle to the foresets

that dip down, away from the bedding plane.

And the foresets will give us an idea

of the direction of current flow,

whereas by measuring the bedding plane

it just tells us some structural geological information.

Jonny's doing well, wedging his hands and fingers

into the weathered rock surface to pull himself upwards.

'This section is tough, and it being damp makes matters worse.'

'Jonny needs to carefully balance and transfer his weight

'from foot to foot.'

Trust those feet, Jonny.

Trust them!

Push down with your palms to push you up higher.

Yes, perfect.

Excellent. Brilliant, well done.

'Another chance to take some vital readings, he's making great use

'of this well-defined bedding plane to act as a ledge to stand on.'

It looks like it could be the front of crossbeds.

OK, it's 21.

About...

20.

It's definitely about 20, I think.

What this climb is allowing us to do is get a really good profile

through the rock section to see if the lithology,

if the type of rocks are changing.

And here we are about half way up the climb now, and just having

a quick look at it, we still have the same type of sandstone.

Being a Cornish granite climber, this should be second nature to you.

'This is called a mantelshelf.

'He needs to push with his hands and arms

'to get his weight over the ledge.

'Really tough.'

Brilliant, well done.

Brilliant, fantastic.

'At last, after an agonising wait, Anna heads on up.'

So, here on the climb, it's worthwhile just looking

at the grain size of the rock we have in front of us.

And using this grain size card, we can quickly measure

how big the grains of sand are in this gritstone.

Simply compare the size of the grains.

They seem to be a coarse sand to a very coarse sand.

With occasional larger pebbles of quartz,

which are rounded sub-angular.

Though the majority is this coarse sandstone.

The roundness of the grains tells us how far they've been transported

from where they were originally weathered.

A well-travelled grain is smooth and round.

The more angular, the more local.

That's the most important bit on this first section.

It's all about your feet.

Oh!

You're doing really well here.

It gets greener and slimier right above where you are there.

That's it.

Yes.

Oh!

'Anna's doing really well.'

'The lower part of this climb is hard because there are

'so few defined bedding planes to provide good climbing holds.'

I'm going to take another measurement here.

'Anna's checking grain size as it can tell us

'a lot about the energy of water flow.'

'Large grains point to fast-flowing, high energy water,

'whereas small grains indicate a lower energy.'

Further down, there was a few, like, coarser ones within the finer ones.

But here there doesn't seem to be as many, like, coarse ones.

OK, then. That's a really good observation.

'Anna is climbing up a vertical joint here,

'very typical of grit stone.

'These joints allow the climber to wedge in their feet and hands

'and to get good purchase.'

-Well done, Anna. You're doing well.

-Great.

Quite large, but slopey rounded holes there.

'They missed a trick not picking the notebook

'but full marks for taking the initiative

'and writing on their hands.'

You can see, just the rocks in front of us here

is slightly, slightly polished.

Very clear if you look down at the slab, see, it's mostly green,

apart from the lighter-coloured areas

where people have been using little bits for their feet.

So even on this tough, millstone grit that was used

to make grinding stones,

it still does wear away and polish down a bit.

So where the fine grain sand sediment is weathering away,

it leaves these big ledges

that weather and erode into these slopey surfaces.

In climbing terms, we call them slopers.

'The top of this climb is so different from the base.'

'Large joints have created a chimney effect

'which is tricky to squirm up and through.'

Brilliant.

Brilliant, well done.

That's an almighty stretch.

Fantastic.

So, just to remind you, we asked Jonny and Anna to find out

if the sediments that formed these rocks are from an ancient

river delta or deep marine environments,

and are they the right way up?

We've got twenty minutes to look at your evidence and observations,

and come up with an interpretation

and conclusion to the question we asked you earlier on.

-OK.

-Well done, brilliant.

You've had some time to sum up your evidence. How's it been?

Has it been easy or difficult?

Well, some bits have been easier than the others.

It's easier to tell where it was deposited than which way up it is.

We think it was a delta, because if it was a deep marine environment

then there would be bigger grains at the bottom and smaller at the top.

But it's been fairly consistent the whole way through,

which indicates it might have been a delta, rather than deep marine.

So rather than having sporadic influxes of sediment

which then settle the coarse grains first,

medium, then going into fine mud,

we are just seeing sandstone, sandstone, sandstone.

Yeah, it's just a very similar thickness the whole way through.

Why is that like the river?

There is cross-bedding that indicates that there was a flow of water

going over the bed when it was deposited and you wouldn't get

that in deep marine because there is not usually a current.

But the way up structure, then,

whether or not this is the right way up.

Why did you struggle there?

We just don't think that we got enough evidence

to say which way up it was.

It wasn't conclusive.

There were different things that indicated it was upside down

and things that indicated that it was the right way up.

If it was the right way up, it would be like a...is it concave?

Yeah, that's right.

Yeah, and if it was the wrong way up, it would be more...

Convex.

Yeah, convex. That's the one.

And you're saying that here, because they're so large,

you can't really see the curve, it just seems to be straight.

Yeah.

I really like your interpretation of ruling out

the deep marine environment in favour of the delta.

So, well done, guys.

I think that was brilliant that you accepted that you just haven't got

enough data to answer the second part of the question

and that's the way geology and science goes.

Today's challenge was all about the present

being the key to the past - uniformitarianism.

Let's look in detail what happened here.

During the Carboniferous period...

Finer grained sediments form.

Here's a calm, sometimes marshy area with muddy or fine sand.

Here's a cross section through a delta sea transition.

Repetition of the sea levels rise-fall-rise

produces mud-sand-mud-cycles.

What was really impressive was that they were not afraid to say

that they didn't have enough information

to answer part of the question.

The day's been changeable, we've had some mist, we've had some rain.

I had good fun on the climb, having had a little slip myself.

'But that is all part of climbing.'

Did I put my climbing shoes on?

Really good way of combining climbing and geology together,

which are two of my favourite things.

The climb was really, really good.

It was quite difficult at the bottom and then it was a bit simpler

in the middle, because there were more handholds and footholds.

And then the chimney bit was quite difficult and scary.

And then we got pulled over the edge, and then you were done.

So that's it's from our three climbs.

I hope the three challenges have helped you think about how to

gather and test evidence to uncover how a landscape is formed and shaped,

and also show how field study can be an exhilarating part of this.

I'd love a scone. Thank you very much, sir.

Ha-ha!

That's Bulgarian.

Bulgarian?

That's the most beautiful knot I've ever seen.

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