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UPLAND .LIMESTONE . LANDSCAPES

Introductie

Twee dagwandelingen in de
Yorkshire Dales:

Introductie
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Iedere Nederlander en Belg is wel een keer naar Han en Remouchamps geweest om de karstverschijnselen te bewonderen.
De Engelsen hebben daar een verbeterde versie van in de Yorkshire Dales.
Ten oosten van Ingleton kun je een breed scala aan boven- en ondergrondse verschijnselen bezichtigen. Warm aanbevolen.

De onderstaande twee dagwandelingen geven een goede eerste indruk.
Ze stonden allebei hoog in de Britain's Favourite Walks: top 100.
Wandeling 1 : Malham and Gordale Scar
Deze eindigde op een zeer fraaie 3 de plaats en
Wandeling 2 : Ingleborough stond op de 25 ste.
Doen dus, die twee wandelingen.

Wandeling1

Wandeling 1: Malham & Gordale Scar
(3 de plaats in de TOP 100)
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Yorkshire Dales National Park
12 km ......... middelzwaar
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A beautiful countryside walk that’s full of surprises.
Malham Cove and Gordale Scar are two of the most spectacular geological features in Britain.

This circular walk from the pretty village of Malham visits two geological wonders – Malham Cove and Gordale Scar – in one action-packed walk through the Yorkshire Dales National Park.

Malham Cove was once a mighty waterfall, with its curved limestone cliffs eroded and sculpted by ice and water over millions of years.
Today the water flows underground and the cliffs are popular with climbers and nesting peregrines (= slechtvalken) , with steep steps leading up the Cove’s left flank to the spectacular limestone pavement (kalksteenplaveisel).
That are areas of bedrock exposed by glacial scouring and fashioned by water into blocks known as clints separated by fissures (spleten) known as grikes. (Walk carefully, to avoid breaking ankles! )

From the limestone pavement your route visits Malham Tarn before heading south to the impressive ravine of Gordale Scar, with its steep walls and stunning water cascades (cascade = a multi-step waterfall)
If you’re feeling brave you can scramble down to the base of the gorge, where a beautiful riverside path leads through woodlands and past the picture-perfect waterfall of Janet’s Foss back to Malham village.

IMPORTANT:
Take care if you decide to scramble up or down the waterfall at Gordale Scar. The route is obvious and the handholds are good, but the rocks can be slippery, particularly after periods of heavy rain.

• Start / finish: at Roadside Parking in Malham.

• Malham National Park Cente: heeft brochure van de Malham Trail.

• Maps: OS Explorer OL2 , OL41


• Malham Cove is a cliff of 70 m high and 270 m wide.
• Hierover stortte lang geleden een brede rivier met waterval naar beneden.


• Limestone pavement (kalksteenplaveisel) above Malham Cove.


• Gordale Scar, a dramatic limestone gorge (kloof) containing two waterfalls with overhanging limestone cliffs more than 300-feet high.



Totale stijging = 550 m

Verdere info:
• www.happyhiker.co.uk/MyWalks/
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• www.geolsoc.org.uk/GeositesMa
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• https://osmaps.ordnancesurvey.c

Wandeling2
Wandeling 2 : Ingleborough ( 724 m)
( 25 ste plaats in de TOP 100 )
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Yorkshire Dales National Park
18 km .......zwaar .

The finest route up the finest hill in the Dales.
The ascent passes legendary caves (grotten) and beautiful becks, with stunning 360 views from the summit.

This rugged circular walk is a Yorkshire Dales classic, exploring Ingleborough’s most famous features on the way to its mighty summit.
With an altitude ( = hoogte boven zeeniveau) of 724m Ingleborough is the second highest of the legendary Yorkshire Three Peaks, but it’s by far the most well known peak in the area.

This sprawling giant’s flanks are dotted with:
- limestone pavements (kalksteenplaveisels) ,
- gills/ghylls (rivierkloven)(= ravines carved by a mountain stream (bergbeek)) ,
- caves (grotten) ,
- doline, sinkholes (=doline) (= A basin in limestone areas down which water disappears.
- scars (kliffen).

This walk follows Clapham Beck to Trow Ghyll then passes the famous cave of Gaping Gill (ook wel Gaping Ghyll), one of the largest underground chambers in Britain.
You eventually climb to the summit via smaller the outlying peak of Little Ingleborough, then return via a different route that heads roughly east from the top of Ingleborough on the Dales High Way before sweeping south towards Clapham.
Described by legendary guidebook writer Alfred Wainwright as the finest of all routes up Ingleborough, this is a must for hill walkers.

• Start / finish: Clapham.

• Map: OS Explorer OL2


1. Entrance of Ingleborough Cave.


2. Walking up through Trow Gill, a dramatic limestone gorge.


3. Fell Beck plunges 100m down into the limestone plateau creating Britain’s highest unbroken waterfall. It lands on the floor of Gaping Gill, the largest cave system in Britain.


4. Ingleborough seen from Little Ingleborough.


5. Ingleborough summit plateau with summit trig and shelter.



Totale stijging = 840 m

• Route volgens happyhiker.co.uk

Verdere info:
• www.youtube.com/watch?v=ayNKy
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• https://osmaps.ordnancesurvey.co.

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A. What is limestone ?

Introduction
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Limestone (kalksteen) is a sedimentary rock, most of which originally formed by the accumulation of sediments rich in carbonate minerals, like calcite, underwater.
These sediments, which were turned to limestone rock over millions of years after they were laid down, are composed of over 50 per cent carbonate minerals.

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1. Weathering (=verwering)
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What do we mean by 1. weathering and 2. erosion ? 
1. Weathering  is not the same as 2. erosion, although they are sometimes confused. Weathering processes do not involve transportation.

What is weathering?
1. Weathering (=verwering) is the breaking up of rock into small pieces.

There are two types of weathering:
1.a. mechanical and 1.b. chemical ......

( 1.b. chemical weathering is the most important way that limestones are broken down and we are going to concentrate on this.)

1.b. chemical weathering (= chemische verwering)
A lump of limestone is very hard – hard enough to be used as a building material. The Pyramids of Egypt are made of limestone and they have lasted a few thousend years – and look good for another few thousend years more.
But limestone is made of calcium carbonate (=calciumcarbonaat) and calcium carbonate suffers from 1.b. chemical weathering.
When raindrops fall through the atmosphere they absorb carbon dioxide (kooldioxide) from the air which makes rainwater a very weak acid.
When it reaches rocks such as limestone, the acid in the raindrops starts to dissolve (oplossen) the calcium carbonate and then removes it in solution (in oplossing).
This process of solution (oplossen) is a type of 1.b. chemical weathering.
This is the main way in which limestone begins to wear down (afbreken).
Just like the processes of 2. erosion, the processes of 1. weathering are very slow. Limestone dissolves at a rate of about 1 cm in every 250 years.

1.a. Mechanical weathering (mechanische verwering)
Limestone is also worn down (afgebroken) by mechanical weathering because it has many vertical cracks (= scheuren, barsten) in it.
An example is 'freeze – thaw' weathering where water soaks into the cracks (=scheuren) and fissures (=spleten), expands when it freezes in the winter, and mechanical breaks the limestone.
The pieces of rock broken off by freeze-thaw action often build up at the bottom of steep hillsides as scree slopes ( puinhellingen).

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2. Erosion

Erosion involves the break down (afbraak) of the rock and then the transportation of the rock fragments.
Rock is eroded by ice (glaciers, etc.), wind, rain, rivers, sea and even by humans or other animals.

Sand and pebbles (=grind) are found in streams (beken) and rivers as well as in many limestone caves.
These cause erosion by scouring, particularly when the river system is in spate (gezwollen) , such as after exceptional storms or during very wet winters.

There is evidence of considerable erosion in karst areas of Britain, but erosion that took place in the geological past.

Glacial erosion
Much of the scenery of the Yorkshire Dales, for example, is the result of erosion by thick ice fields and glaciers during the last ice ages.

As glaciers moved over the landscape, they scoured away enormous quantities of rock. Evidence of glaciation is everywhere: 


1. U-shaped valleys:
The term given to a valley when it has been eroded by glaciers.
Its cross-section is U-shaped.


• Fig: The formation of a . U - shaped valley.



2. Scars (kliffen)
A scar is a limestone cliff formed along a side of a valley (dalhelling).
When glaciers during the last ice age moved down the valleys, the side of the valley was scoured and the rock plucked away to leave long cliff-like scars.

The exposed surface is affected by freeze-thaw action on the well-jointed limestone (kalksteen met veel vertikale scheuren)
Water enters the cracks (= scheuren) , and if it freezes, expands.
As the water expands, so do the cracks.

Repeated freezes and thaws eventually break off rock, and at the bottom of the scar cliff a talus or scree slope (= puinhelling) is formed.
A dramatic example of scar landscape can be found at Twistleton Scar, in the Yorkshire Dales.

• The limestone cliff Twistleton Scar with scree slope at the bottom.

3.Erratics (= zwerfkeien):
The glacial history of the karst of Yorkshire is reflected in the huge erratic blocks that are seen, particularly around Norber.

Here, Silurian sandstone blocks 2 m high rest on the limestone.

The erratics (zwerfkeien) were carried uphill from Crummackdale by the ice.
In some cases, the erratic block protects the underlying limestone from chemical weathering, and during the last 10 000 years the surrounding limestone has been lowered so that the erratics now appear to stand on limestone plinths up to 0.5 m high.

• One of the Norber erratics, a gritstone boulder perched (=zittend) on little pedestrals of. limestone.

4. Till (=till, grondmorene)
Formed as moraine (=morene) that was dumped from a glacier when the ice retreated (slonk, terugweek).
It comprises muds, silts and sands mixed with pebbles and boulders.

5. Gorges:
Towards the end of the last ice age, meltwater from the retreating ice, near what is now Ingleborough, was not able to take its normal subterreanean route, because the cave system was blocked by permafrost.

Instead it rushed over the surface, down what is now Fell Beck and cascaded
(tumbled down over a series of rock steps) into Clapdale, rapidly eroding the dale floor.

When the glaciers were in retreat, huge quantities of water would have flowed through Trow Gill.

The meltwater cut down rapidly through the rock, eroding a spectacular gorge, 20 m deep in places and only 3 m wide at its narrowest.

However, the glaciers had also eroded away the valley floor, lowering the level of resurgence (verschijnen). For this reason, with the disappearance of the ice fields and glaciers, the water followed a new subterranean route to the new resurgence level, and Trow Gill was left 'high and dry'.


• Trow Gill.

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B. Limestone topography

Introduction
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The topography of limestone landscapes — the features (= vormen), you can see on the surface, also called landforms (landvormen, reliëfvormen) or geomorphology — are very characteristic and are created by 1.b. chemical weathering and 2. erosion.

• Topographical features (vormen) created by 1.b. chemical weathering:
Chemical weathering results in a number of characteristic solution features in a limestone landscape, such as limestone pavements , dolines (also called sinkholes) and swallow holes.
This type of landform is called karst.

• Topographical features (vormen) created by 2. erosion:
Erosional features like blind valleys, gorges and waterfalls are created by the transport of broken rock across the land.
Erosion has a number of causes, including glaciers and rivers.

We will use further on the area around Ingleborough in the  Yorkshire Dales  as an example to illustrate the landforms.

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1. Topographical features (=vormen) created by
... 1.b. chemical weathering

Acidic rain water makes limestones dissolve when the calcite is taken in solution as a result of 1.b chemical weathering.
This results in the formation of a number of solution features (oplossingsvormen) that are characteristic of karstlandscapes, such as the Yorkshire Dales.

Solution features only form in areas of high rainfall and particularly where river systems can develop, and in Yorkshire they vary in size from very small to very large.

Features characteristic of 1.b. chemical weathering:
1. limestone pavements (kalksteenplaveisels) made up of clints (blokken) and grykes (spleten).
2. dolines (dolines) (also called sinkholes)
3. swallow holes (verdwijngaten)

1. Limestone pavements (=kalksteenplaveisels)
Limestone pavement =
area of bedrock exposed by glacial scouring (=erosion) and fashioned by water (=1.b. chemical weathering) into blocks known as clints separated by fissures (spleten) known as grikes.


• Limestone pavement (=kalksteenplaveisel) above Malham Cove.
• The clints (=blokken) are formed by the solvent action of rainwater on grikes (=spleten). in the limestone.
• Doordat kalksteen relatief gemakkelijk oplost in regenwater, zijn de scheuren door de tijd brede spleten geworden.

High above fields and villages a hilltop limestone pavement, like that of Malham Cove, attracts a host of walkers and naturalists.
The pavement crevices (spleten) form a habitat where plants and animals live sheltered and secure.
An expanse of bare white rock stands at the head of a 70 m high cliff.
Nearby, a little group of sheep rests silently, sheltered from the heat of summer by a lonely clump of trees (boomgroep).
The scene has a biblical air, and if asked to guess its whereabouts, you might first be tempted to say the Middle East.
Few would be quick to tell its true location - the hill country of northern England. And few would guess that this barren scene with its shimmering surface of rock was shaped by ice.
Long ago the original limestone was worn down to its flat table shape under the immense weight and grinding power of millions of tons of ice.

During the later ice ages, up to a million years ago, the glaciers and ice sheets (ijskappen) worked as far south as where the Midlands are today.
The wide, graceful U-shaped valleys of the Scottish Highlands, the Lake District and Snowdonia, often holding a blue lake in their deepest part, mark the paths glaciers once took.

Many of us can recognise the sweeping shape of these beautiful valleys as the result of glacial movement , but the limestone pavements appear different ; it seems hard to connect them with the glacial valleys - and yet they were created by the same process.

During the ice ages, the piled-high ice sheets (ijskappen) carries a mighty mass of boulders (keien) and stones, which worked as a vast abrasive, scraping and wearing down (afbreken) the limestone to produce a smooth sheet.

When warmer weather returned and the ice melted away, the boulders and stones were left behind on the pavement top, where many of these erratics (=zwerfkeien) still stand today as evidence of the glacial age.

Since the last ice age the limestone has been subject to open-air weathering.
For more than ten thousand years rain has dissolved and washed away the surface of the limestone, and in places this enlarged the hairline cracks (barsten) that are found in the limestone.
These were originally caused by changes in the pressure on the earth's crust, for example when the ice sheet melted away relieving the rock of its burden.
The crevices (spleten) often form rectangular patterns, from which these limestone expanses gained the name of pavements (plaveisels).

The usual width of a grike (=spleet) is a few inches , but grikes vary in size from thin crevices. (=spleten) to occasional huge troughs which could quite easily accommodate a sheep.

Limestone suffers badly from 1.b.chemical weathering – not just because it is made up of calcium carbonate (calciumcarbonaat) , but also it has lots of cracks (=scheuren) in it.
As is shown in the figure (i) below limestone has horizontal cracks (scheuren) called bedding planes (laagvlakken) and vertical cracks called joints (vertikale scheuren).

2. Dolines/sinkholes (=dolines)
Ingleborough has a large number of dolines along its 
limestone benches, including solution and collapse dolines and
many swallow holes.

3. Swallow holes (verdwijngaten)
Swallow holes are dolines/sinkholes  down which a river or stream disappears via a fissure (spleet) or vertical shaft to join the subterranean drainage (ontwaterings) system below.
Downstream of the swallow hole, a dry valley may occur.

Swallow holes are found in different kinds of limestone areas, including chalk (e.g. in the Chilterns and North Downs), although there they are small.
In the Yorkshire Dales, however, swallow holes may form wide, vertical shafts (known as potholes) , leading to extensive cave systems.

Perhaps the most spectacular is Gaping Gill.
Here, Fell Beck, which drains Simon Fell on the eastern side of Ingleborough, cascades down a vertical shaft to the cave floor 100 m below ground.
Gaping Gill forms Britain's largest unbroken waterfall.


• The pothole of Gaping Gill   (a special type of  swallow hole.)
Here, Fell Beck, which drains Simon Fell on the eastern side of Ingleborough, cascades down the vertical shaft to the cave floor 100 m below ground.
(cascade (werkwoord)= tumbling down over a series of rock steps).

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2. Topographical features (=vormen) created by
...... erosion

2. Erosion involves the movement of fragments of rock, and therefore differs from 1. weathering, which is just concerned with the decay of rock.

Although most features (=vormen) in areas of massive limestone are solution features (oplossingsvormen) caused by 1.b. chemical weathering, the effects of 2. erosion can also be seen.

2. Erosion is caused by a number of agents including ice (e.g. glaciers), wind, water (e.g. rivers and the sea) and even humans and other animals.

In this section we focus on the erosional features in the karst landscape of the Yorkshire Dales.

Features (vormen) characteristic of erosion
1. blind valleys
2. gorges
3. waterfalls

1. Blind valleys.
Blind valleys are one of the characteristic features of karst scenery.
They carry a stream for part of their course, but then the water disappears down a doline  (=doline) or swallow hole (=verdwijngat).

On the flanks of Ingleborough, a number of streams (beken) flow over the sandstones and shales on the summits of the hills, but disappear underground when they reach the limestone.

There are a few blind valleys on Ingleborough, but they occur where there is a cover of glacial till that allows the streams that originate on the upland areas to flow over the limestone.

Rivers that flow off Simon Fell have formed several blind valleys between Newby Moss and the Allotment, although none are large.

Fell Beck forms a blind valley where it disappears down Gaping Gill.
The beck flows off the sandstone and shales onto the till, which it erodes to disappear down the swallow hole.

Downhill from Gaping Gill, there is no river to erode the till.
Uphill of the swallow hole (verdwijngat), however, the river continues to erode so that it is much lower here than on the downhill side.
A cliff forms downhill of the swallow hole, facing uphill.

A little further east, the Allotment potholes and Marble Steps Pot also provide examples of blind valleys.

2. Gorges (e.g. Trow Gill).
Towards the end of the last ice age, meltwater from the retreating ice, near what is now Ingleborough, was not able to take its normal subterreanean route, because the cave system was blocked by  permafrost.

Instead it rushed over the surface, down what is now Fell Beck and cascaded into Clapdale, rapidly eroding the dale floor.

When the glaciers were in retreat (slonken, terugweken), huge quantities of water would have flowed through Trow Gill.

The meltwater cut down rapidly through the rock, eroding a spectacular gorge, 20 m deep in places and only 3 m wide at its narrowest.

However, the glaciers had also eroded away the valley floor, lowering the level of resurgence (verschijnen). For this reason, with the disappearance of the ice fields and glaciers, the water followed a new subterranean route to the new resurgence level, and Trow Gill was left 'high and dry'.

• Trow Gill.

3. Waterfalls
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Underground features

Introduction

Karst features form under the ground as well as on the surface.

There are 2 dominant processes involved in creating underground features in karst regions:
a. solution (= oplossen) = a salt or mineral that has dissolved and held in water.
This process forms 1. caves and 2. resurgence (springs)
b. precipitation (=neerslaan) = when salts or minerals, such as calcite, come out of solution and are deposited on a rock surface.
This process forms e.g. 1. stalactites, 2. stalagmites, 3. pillars

Gaping Gill cave system
We will examine examples of those features found in the Yorkshire Dales, notably the cave system of Gaping Gill near Ingleborough.

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1. Underground solution (oplossing) features

1. Caves (=grotten) and Caverns (=grote grotten)
Cavern = a term generally regarded as synonymous with cave, though sometimes implying one of large dimensions.
Dit laatste doet men in dit boek. Men gebruikt dus het woord cavern in de betekenis van grote grot.
Caves (grotten) are natural underground tunnels that may widen in places to form caverns (grote grotten).
Caves in karst regions like the Yorkshires Dales were created as a result of solution.

The water that enters the limestone through a swallow hole (=verdwijngat) makes its way down through the rock.
It flows along the many joints (vertikale scheuren) and bedding planes (=laagvlakken) dissolving the limestone as it goes.
Caverns (grote grotten) form where some of the underground limestone is dissolved more quickly than the rock around it. This happens in places where the rock has many joints and bedding planes close together ( figure A).
These cracks (scheuren) become fissures (spleten) and allow the passage of lots of water, which dissolves away the rock completely and a cavern forms (figure B).

2. resurgences (verschijngaten)
Water flows through limestone in karst regions, but eventually re-appears at the surface level at resurgences (verschijngaten) or springs (bronnen).

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2. Underground precipitation (neerslag) features

There are many underground features that are created by precipitation of minerals, e.g.:

1. Stalactites (=hangende druipstenen),

2. Stalagmites (=staande druipstenen) and

3. Pillars (pilaren; zuilen)

1. The water that drips down into the caverns is laced with calcium carbonate (=calciumcarbonaat) that has dissolved on its passage through the rock.
The water drips from the cavern roof very slowly so that some of it evaporates.
When it evaporates it leaves behind the calcium carbonate, which is deposited on the cavern roof.
When calcium carbonate is deposited it is called dripstone (druipsteen).
The water continues to drip, evaporating as it does so, and the deposites build up to form fingers of dripstone that grow downwards into the cavern (see figure)
They are called stalactites (hangende druipstenen) and grow by only a few millimetres a year.
They grow slowly partly because the water cannot hold much dissolved limestone and partly because the caverns are cool, so only a little evaporation takes place.


2. Some of the water drips onto the cavern floor where it also may evaporate.
It leaves behind calcium carbonate here as well, which is deposited as dripstone on the cavern floor.
As more water drips down, more is deposited, forming fingers of dripstone that grow upwards from the cavern floor.
They are called Stalagmites and grow just as slowly as stalactites.

3. Sometimes stalactites and stalagmites join together to form Pillars (=pilaren, zuilen)

Overzichtskaart
D. Limestone areas in
... England and Wales

• There are three types of limestone in the British Isles, but the one that forms the highest upland areas is Carboniferous limestone (kalksteen uit het Carboon).
• Links van de diagonale lijn liggen de uplands ( gebieden hoger dan ongeveer 1,000 feet.
• Dus in Engeland zijn de belangrijkste upland limestone landscapes:
Northumberland NP , Lake District NP , Yorkshire Dales NP , North York Moors NP. en Peak District NP.
• Je ziet dat North York Moors NP wel uplands is, maar geen Carboniferous limestone heeft, In plaats daarvan heeft ze de zachte, geelachtige. Jurassic limestone.
Ook de Cotswolds heeft die zachte, geelachtige kalksteen. De Cotswolds heeft. echter overal enclosed (=omheind) farmland en is geen upland.)

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LAATST BIJGEWERKT : 7-1-2019