A UNESCO Global Geopark

As well as being designated as an Area of Outstanding Natural Beauty (AONB), the North Pennines is also a UNESCO Global Geopark.

What is a UNESCO Global Geopark?UNESCO Global Geoparks are places where outstanding geological heritage is used to support sustainable development, through conservation, education, interpretation and nature tourism. Each Geopark in Europe is a member of both the European and Global Geoparks Networks, where Geopark staff and partners collaborate to share ideas, raise funds and carry out projects. Visit www.unesco.org/geoparks

Places like Killhope, the North of England Lead Mining Museum(above) are vital parts of our Geopark. At this hands-onattraction you can find out how North Pennine lead miners livedand worked and how this once-important industry helped toshape the landscape and communities we know today.

Geology of the North Pennines

Foundations of the landscape

Foundations of thelandscapeThe North Pennine landscape has its foundation in theunderlying rocks and the geological processes which haveshaped it over 500 million years of Earth history. Over thisvast period of time the piece of the Earth’s crust containingwhat is now the North Pennines has travelled through manylatitudes. Tropical seas, rainforests, molten rock, deserts andice sheets have all helped create the bare bones of today’slandscape. People arrived here about 10,000 years ago,heralding a new stage in the evolution of the NorthPennines – a landscape that is continually evolving throughnatural processes and human activity.

The oldest rocksThe deep roots of the North Pennines are slates and volcanic rocks, which formed between 500 and 420 million years ago, in the Ordovician and Silurian periods of Earth history. These rocks were once mudand volcanic ash at the edge of a wide ocean. When the oceanclosed about 420 million years ago, they were squashed and alteredto form hard slaty rocks. They are mostly buried, but can be seen inone part of Upper Teesdale and form distinctive conical hills (the'Pikes') along the North Pennine escarpment.

Alston

Stanhope

FrosterleyWolsingham

Middleton-in-Teesdale

KirkbyStephen

Brough

Castleside

Allendale

Allenheads

Killhope

Blanchland

Rookhope

Eastgate

St John’s Chapel

Cowshill

Ninebanks

Newbiggin

Slaggyford

Dufton

Melmerby

Garrigill

CrossFell

Nenthead

Castle Carrock

Bowes

Cotherstone

High Force

Cow Green Reservoir

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Red sandstones and shales

Slates, sandstones and volcanic rocks

The Whin Sill (dolerite)

Carboniferous

Permian

& Triassic

Ordovician

& Silurian

Alternations of thin limestones, shales,thick sandstones and thin coal seams, with the Great Limestone at the base

Alternations of limestone, shale,sandstone and coal

The ‘Coal Measures’ – shales, siltstones, sandstones and coal seams

Carboniferous rocks(limestone, shale,sandstone, coal)

Whin Sill

Glacial deposits

Permian and Triassicsandstones and shales

Ordovician and Silurianslates and volcanic rocks

Weardale Granite

Permian and Triassicsandstones and shales

Carboniferous rocks(limestone, shale,sandstone, coal)

Whin Sill

Glacial deposits

Ordovician and Silurianslates and volcanic rocks

Weardale Granite

Weardale Granite and the Alston BlockAbout 400 million years ago, a huge mass of molten rock rose upunder what is now the North Pennines. It cooled and crystallizedunderground to form the Weardale Granite – a hidden but fundamentalgeological feature. Granite is less dense than most other rocks in theEarth’s crust and is relatively buoyant. Because of this, the area abovethe granite – much of the North Pennines – has remained higher thansurrounding areas for millions of years, and is known by geologists asthe ‘Alston Block’.

The oldest rocksThe deep roots of the North Pennines are slates and volcanic rocks, which formed between 500 and 420 million years ago, in the Ordovician and Silurian periods of Earth history. These rocks were once mudand volcanic ash at the edge of a wide ocean. When the oceanclosed about 420 million years ago, they were squashed and alteredto form hard slaty rocks. They are mostly buried, but can be seen inone part of Upper Teesdale and form distinctive conical hills (the'Pikes') along the North Pennine escarpment. This simplified geological map of the North Pennines

shows the main rock units which lie at or near theEarth’s surface

Weardale Granite (from aborehole at Rookhope)

Schematic cross-section through theNorth Pennine escarpment (from theEden Valley in the west up to theCross Fell range)

The ‘Pikes’ (to right of image) are made of theNorth Pennines’ oldest rocks

Front cover: The Whin Sill at High Cup NickUnless otherwise credited, all photographs © NPAP/Elizabeth Pickett, Chris Woodley-Stewart

Elizabeth Pickett © B

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Geology based upon an image derived from BGS digital databy permission of the British Geological SurveyBase map © Crown Copyright. All rights reserved. Durham County Council LA100049055. 2015.

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The North Pennine landscape has its foundation in the underlying rocks and the geological processes which have shaped it over 500 million years of Earth history. This leaflet provides a useful overview of this amazing history.

North Pennines AONB Partnershipwww.northpennines.org.uk+44 (0)1388 528801info@northpenninesaonb.org.uk

NorthPenninesAONB

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Printed on 150gsm Cacoon 100% recycled Silk

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The North Pennines is one of England’s most special places – a peaceful, unspoilt landscape with a rich history and vibrant natural beauty. In recognition of this it is designated as an Area of Outstanding Natural Beauty (AONB). The area is also a UNESCO Global Geopark.

AONBsAONBs, along with National Parks, represent some of our finest countryside and are within a worldwide category of Protected Landscapes. The North Pennines was designated in 1988. It includes parts of the counties of Durham, Northumberland and Cumbria (and a very small part of North Yorkshire), and at nearly 2,000km2 it is the second largest of the 38 AONBs in England and Wales. Visit www.landscapesforlife.org.uk

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Tropical seas and swampsAbout 360 to 300 million years ago – in the CarboniferousPeriod – the North Pennines lay near the equator and wasperiodically covered by shallow tropical seas. Skeletons of seacreatures accumulated as limy ooze on the sea floor. Riverswashed mud and sand into the sea, building up deltas on whichswampy forests grew. In time, the limy ooze became limestone,the mud and sand became shale and sandstone, and the foreststurned to coal. Periodically, the sea flooded in, drowning thedeltas and depositing limestone again. This cycle happenedmany times, building up repeating layers of limestone, shale,sandstone and coal, known as ‘cyclothems’. Many of these layerscontain fossils which tell us about the animals and plants thatlived in these ancient seas and swamps.

Limestone and sandstone are resistant to erosion, whereas thesofter shales wear away more easily. This contrast has producedthe terraced hillsides of the North Pennines and can be seen insome of the area’s waterfalls.

Limestone also has its own special landscape features. Despite being ahard rock, it dissolves gradually in rainwater to form sinkholes, cavesand limestone pavements. While molten, the Whin Sill baked the adjacent limestone, creating

the ‘Sugar Limestone’ of Upper Teesdale. Soils formed on thisunusual rock support some of the rare arctic-alpine plants of the'Teesdale Assemblage'.Limy ooze on the sea floor

hardened into limestone

Formation of the layeredCarboniferous rocks ofthe North Pennines

Fluorite

Lead mine entrance and spoilheaps at Nenthead

Formation of North Pennine mineral veins

Ashgill Force in theSouth Tyne Valley

© NPAP/K Gibson

Terraced hillsides in Weardale

Formation of the Whin Sill

The River Tees flows over theWhin Sill at High Force

Sugar Limestonenear Cow GreenReservoir, on theMoor House - UpperTeesdale NationalNature Reserve

Buildings of redsandstone in Dufton

Sinkhole on Herdship Fellin Upper Teesdale

Limestone pavement atStainmore, east of Brough

The North Pennine escarpment about 250 million years ago

Small hill of glacial debris, known as a drumlin,at Holwick in Upper Teesdale

Peat, with ancient woodat its base, on glacial

material near Allenheads

Mineral richesThe North Pennines is famous for its mineral deposits. Veins oflead ore and other minerals formed about 290 million years agowhen mineral-rich waters, warmed by heat from the buriedWeardale Granite, flowed through fractures underground. As thefluids cooled, their dissolved minerals crystallized within thefractures, forming mineral veins.

These mineral deposits were the foundation of the area’seconomy for many centuries. Most important was lead mining,which had its heyday in the 18th and 19th centuries.Commercially mined minerals include galena (lead ore),sphalerite (zinc ore), iron ores, fluorite (or fluorspar) and bariumminerals. Mining has had a profound effect on the North Penninelandscape, leaving a legacy of settlements, shafts, spoil heapsand chimneys.

The Whin SillStretching of the Earth’s crust 295 million years ago causedmolten rock to rise up and spread out between the layers ofCarboniferous rocks. It cooled and solidified underground toform the Whin Sill, a vast sheet of hard dark dolerite (knownlocally as whinstone). After millions of years of erosion the WhinSill is now exposed at the surface in several places. Its cliffs formdramatic landscape features in Upper Teesdale and along theNorth Pennine escarpment.

Deserts and floodsThe Eden Valley is underlain by red sandstones andshales, which formed between 290 and 210 millionyears ago, in the Permian and Triassic periods. TheNorth Pennines baked in a desert environment justnorth of the equator, and these rocks formed from sandand mud laid down in dunes and rivers. You can seethese red rocks in the buildings along the foot of theNorth Pennine escarpment.

Ice ageThe North Pennines owes much of its character to the action of iceand meltwater in the more recent geological past. About 20,000years ago a kilometre-thick ice sheet covered the area. It streamedacross the landscape, scouring and smoothing the fells and dales,and dumping clay, gravel and boulders.

After the iceAbout 15,000 years ago the ice melted, creating torrentialmeltwaters and leaving a landscape of bare rock and glacialdebris. Arctic plants, shrubs and eventually trees colonised thebare land. About 7,500 years ago, a period of increased rainfall,perhaps combined with woodland clearance by early settlers, ledto the formation of peat on the uplands.

Today’s landscapeToday’s North Pennine landscape is the product of millions ofyears of geological processes and thousands of years of humanactivity. All these have helped create both the shape of thecountryside and the intricate blanket of land use and settlementdraped over it. And it is still evolving...

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Sand deposited in river deltashardened into sandstone

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Swampy forests grew on top of the deltasand eventually became coal seams

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The sea flooded the deltas,depositing more limy ooze – andthe cycle started again

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