Limy ooze on the sea floor hardened into limestone

Mud washed in byrivers became shale

Sand deposited in river deltas hardened into sandstone

Swampy forests grew on top of the deltas and eventually became coal seams

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

1

2

3

4

5

Allen Banks GeotrailRocks, roots and rivers

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 Global Geopark – an accolade endorsed by UNESCO.

A 2¾-mile circular walk at Allen Banks, exploring landscape, rocks, plants and evidence of an industrial past.

Supported by:

01/1

5/6K

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

NorthPenninesAONB

@NorthPennAONB

northpennines

northpennaonb

The AONB Partnership has a GreenTourism award for its corporate office

Welcome to a special landscape……shaped by millions of years of natural processes andcenturies of human activity.

This lovely steep-sided valley along the River Allen has beenlooked after by the National Trust since 1942. It hasextensive ancient and ornamental woodlands, rich in wildlife,and miles of waymarked paths.

The area has a fascinating geological story to tell – of tropicalseas and deltas, molten rock, glaciers and river processes.There are also subtle imprints of an industrial past.

This circular walk will introduce you to some of the specialfeatures of the landscape at Allen Banks. By spotting clues inthe woods, cliffs and river you’ll discover more about itsremarkable past. The sections opposite describe how thelocal rocks formed, and how the landscape has been shapedby ice, water and people.

Walk length/time:4.4 km(2¾ miles) with around40m of ascent, takingabout 1½ hours

Start/finish:National Trustcar park at Allen Banks Gridref NY 798 640. Pay anddisplay for non-NTmembers

Terrain:The walk is onfootpaths and permissivepaths through woodland,and 100m of minorcountry road. The route is relatively flat or gently undulating butthere are a few short, fairly steep ascents and descents. Walkingboots or strong shoes are recommended as some sections areuneven and can be muddy. Please be careful near the river,beneath cliffs and on sections with steep drops to the river. Dogsare welcome but please keep them under close control.

Public transport:For timetable information call Traveline on 0871 200 22 33 (www.traveline.info)

Facilities:Toilets and picnic area at Allen Banks car park

Useful maps:Ordnance Survey1:50 000 Landranger 86 Haltwhistle & Brampton

or 87 Hexham & Haltwhistle1:25 000 Explorer OL43 Hadrian’s Wall British Geological Survey1:50 000 Geological Sheet 19 Hexham

Tropical North PenninesMost of the rocks you’ll see at Allen Banks are layers ofsandstone, shale and limestone. They formed in theCarboniferous Period, between 360 and 300 million years ago.

Back in those distant times, the North Pennines lay near theequator. The area was periodically covered by shallow tropicalseas in which the skeletons of sea creatures accumulated aslimy ooze. Rivers washed mud and sand into the sea, buildingup deltas on which swampy forests grew. In time, the limy oozehardened to limestone, the mud and sand became shale andsandstone, and the forests turned to coal. Periodically, the searose, drowning the deltas and depositinglimestone again.

This cycle happened many times, buildingup repeating layers of limestone, shale,sandstone and coal. Many of these rockscontain features and fossils which tell usabout the seas and swamps and what livedin them.

Molten rock and whinstoneAt Allen Banks there is a small outcrop of a rock type that has avery different origin from the Carboniferous rocks. It is part of afeature known as the Haydon Bridge Dyke which is related tothe Whin Sill, one of the most dramatic landscape features inthe North Pennines AONB and Northumberland National Park.

About 295 million years ago molten rock rose up and spreadout between the layers of Carboniferous rocks. It solidifiedunderground to form hard, dark dolerite (or whinstone). Thisvast sheet of rock – the Whin Sill – is now exposed as crags inseveral places, including along Hadrian’s Wall. The fractures upwhich the molten rock rose are preserved as narrow, verticalsheets of dolerite known as dykes. The Haydon Bridge Dyke,seen on this walk, may be one of these ‘feeder’ dykes.

Sculpted by ice and waterThis landscape owes much to the action of ice and water.About 20,000 years ago a thick ice sheet streamed across thearea, scouring and smoothing the hills and valleys and dumpingclay, gravel and boulders. Torrential meltwater carved gorgessuch as the one at Allen Banks. Water continues to shape thelandscape today; the River Allen is eroding its riverbanks insome places and depositing material in others.

Industrial Allen BanksIt is hard to imagine now but untilthe mid-1800s parts of thepeaceful woods of Allen Banksand Staward Gorge would havebustled with small-scale industry.There is evidence for quarrying,lime burning, mining for lead ore,iron ore and coal, and smelting.

Lead smelt mill ruins seen onthis walk

Allen Banks is looked after by the National Trust andis in the North Pennines Area of Outstanding NaturalBeauty (AONB) and European & Global Geopark

Allen Banks and Staward Gorge – National TrustFor more information on Allen Banks and Staward Gorgevisit www.nationaltrust.org.uk/allen-banks-and-staward-gorge or contact the National Trust office on 01434321888 or allenbanks@nationaltrust.org.uk

European and Global GeoparksThe North Pennines AONB is Britain’s first EuropeanGeopark, a status supported by UNESCO, and afounding member of the Global Geoparks Network.Geoparks are special places with outstanding geologyand landscape, and where there are strong local effortsto make the most of geological heritage throughinterpretation, education, conservation and naturetourism. To find out more visitwww.europeangeoparks.org

Find out more about North Pennine geologyThis leaflet is one of a series of geological publicationsabout the North Pennines. These are part of the NorthPennines AONB Partnership’s work to make the most ofour special geological heritage. This work includesevents, education resources, publications, displays andmuch more…

Alston

Hexham

HaydonBridge Haltwhistle

Allendale

Allen Banks

North PenninesAONB & Geopark

This publication is printed on 150gsm Revive 100 Silk: 100% post-consumer recycled fibre content, chlorine free.

All photos & illustrations unless other-wise credited ©NPAP/Elizabeth Pickett.

With thanks to all the National Trust staff, especially Eric Wilton, who provided helpful information and comments.

Formation of the layered Carboniferousrocks of the North Pennines

Section of fossil rootfrom Allen Banks©Denis Fleming

Formation of the Whin Sill from molten rock

A feeder dyke

Whin Sill

Shale

Limestone

Sandstone

Above: Guided geological walk at Allen BanksFront cover: Cliffs at Raven Crag

©Elizabeth Pickett

©E

liza

beth

Pic

ket

t

Limy ooze on the sea floor hardened into limestone

Mud washed in byrivers became shale

Sand deposited in river deltas hardened into sandstone

Swampy forests grew on top of the deltas and eventually became coal seams

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

1

2

3

4

5

Allen Banks GeotrailRocks, roots and rivers

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 Global Geopark – an accolade endorsed by UNESCO.

A 2¾-mile circular walk at Allen Banks, exploring landscape, rocks, plants and evidence of an industrial past.

Supported by:

01/15/6K

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

NorthPenninesAONB

@NorthPennAONB

northpennines

northpennaonb

The AONB Partnership has a GreenTourism award for its corporate office

Welcome to a special landscape……shaped by millions of years of natural processes andcenturies of human activity.

This lovely steep-sided valley along the River Allen has beenlooked after by the National Trust since 1942. It hasextensive ancient and ornamental woodlands, rich in wildlife,and miles of waymarked paths.

The area has a fascinating geological story to tell – of tropicalseas and deltas, molten rock, glaciers and river processes.There are also subtle imprints of an industrial past.

This circular walk will introduce you to some of the specialfeatures of the landscape at Allen Banks. By spotting clues inthe woods, cliffs and river you’ll discover more about itsremarkable past. The sections opposite describe how thelocal rocks formed, and how the landscape has been shapedby ice, water and people.

Walk length/time: 4.4 km(2¾ miles) with around40m of ascent, takingabout 1½ hours

Start/finish: National Trustcar park at Allen Banks Gridref NY 798 640. Pay anddisplay for non-NTmembers

Terrain: The walk is onfootpaths and permissivepaths through woodland,and 100m of minorcountry road. The route is relatively flat or gently undulating butthere are a few short, fairly steep ascents and descents. Walkingboots or strong shoes are recommended as some sections areuneven and can be muddy. Please be careful near the river,beneath cliffs and on sections with steep drops to the river. Dogsare welcome but please keep them under close control.

Public transport: For timetable information call Traveline on 0871 200 22 33 (www.traveline.info)

Facilities: Toilets and picnic area at Allen Banks car park

Useful maps:Ordnance Survey1:50 000 Landranger 86 Haltwhistle & Brampton

or 87 Hexham & Haltwhistle1:25 000 Explorer OL43 Hadrian’s Wall British Geological Survey 1:50 000 Geological Sheet 19 Hexham

Tropical North PenninesMost of the rocks you’ll see at Allen Banks are layers ofsandstone, shale and limestone. They formed in theCarboniferous Period, between 360 and 300 million years ago.

Back in those distant times, the North Pennines lay near theequator. The area was periodically covered by shallow tropicalseas in which the skeletons of sea creatures accumulated aslimy ooze. Rivers washed mud and sand into the sea, buildingup deltas on which swampy forests grew. In time, the limy oozehardened to limestone, the mud and sand became shale andsandstone, and the forests turned to coal. Periodically, the searose, drowning the deltas and depositinglimestone again.

This cycle happened many times, buildingup repeating layers of limestone, shale,sandstone and coal. Many of these rockscontain features and fossils which tell usabout the seas and swamps and what livedin them.

Molten rock and whinstoneAt Allen Banks there is a small outcrop of a rock type that has avery different origin from the Carboniferous rocks. It is part of afeature known as the Haydon Bridge Dyke which is related tothe Whin Sill, one of the most dramatic landscape features inthe North Pennines AONB and Northumberland National Park.

About 295 million years ago molten rock rose up and spreadout between the layers of Carboniferous rocks. It solidifiedunderground to form hard, dark dolerite (or whinstone). Thisvast sheet of rock – the Whin Sill – is now exposed as crags inseveral places, including along Hadrian’s Wall. The fractures upwhich the molten rock rose are preserved as narrow, verticalsheets of dolerite known as dykes. The Haydon Bridge Dyke,seen on this walk, may be one of these ‘feeder’ dykes.

Sculpted by ice and waterThis landscape owes much to the action of ice and water.About 20,000 years ago a thick ice sheet streamed across thearea, scouring and smoothing the hills and valleys and dumpingclay, gravel and boulders. Torrential meltwater carved gorgessuch as the one at Allen Banks. Water continues to shape thelandscape today; the River Allen is eroding its riverbanks insome places and depositing material in others.

Industrial Allen BanksIt is hard to imagine now but untilthe mid-1800s parts of thepeaceful woods of Allen Banksand Staward Gorge would havebustled with small-scale industry.There is evidence for quarrying,lime burning, mining for lead ore,iron ore and coal, and smelting.

Lead smelt mill ruins seen onthis walk

Allen Banks is looked after by the National Trust andis in the North Pennines Area of Outstanding NaturalBeauty (AONB) and European & Global Geopark

Allen Banks and Staward Gorge –National TrustFor more information on Allen Banks and Staward Gorgevisit www.nationaltrust.org.uk/allen-banks-and-staward-gorge or contact the National Trust office on 01434321888 or allenbanks@nationaltrust.org.uk

European and Global GeoparksThe North Pennines AONB is Britain’s first EuropeanGeopark, a status supported by UNESCO, and afounding member of the Global Geoparks Network.Geoparks are special places with outstanding geologyand landscape, and where there are strong local effortsto make the most of geological heritage throughinterpretation, education, conservation and naturetourism. To find out more visitwww.europeangeoparks.org

Find out more about North Pennine geologyThis leaflet is one of a series of geological publicationsabout the North Pennines. These are part of the NorthPennines AONB Partnership’s work to make the most ofour special geological heritage. This work includesevents, education resources, publications, displays andmuch more…

Alston

Hexham

HaydonBridgeHaltwhistle

Allendale

Allen Banks

North PenninesAONB & Geopark

This publication is printed on 150gsm Revive 100 Silk: 100% post-consumer recycled fibre content, chlorine free.

All photos & illustrations unless other-wise credited ©NPAP/Elizabeth Pickett.

With thanks to all the National Trust staff, especially Eric Wilton, who provided helpful information and comments.

Formation of the layered Carboniferousrocks of the North Pennines

Section of fossil rootfrom Allen Banks©Denis Fleming

Formation of the Whin Sill from molten rock

A fe

eder

dyk

e

Whin Sill

Shale

Limestone

Sandstone

Above: Guided geological walk at Allen BanksFront cover: Cliffs at Raven Crag

©Elizabeth Pickett

©E

lizabeth Pick

ett

RiverAlle

n

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2

3

45

67

8

9

10

StartP

11

12

to A69

N

Suspensionbridge

RavenCrag

BriarwoodBanks

Plankey Mill

Bridge

Start: From the National Trust car park follow theriverside path south.

Delta rocksAbout 30m beyond the stone steps that join the path onthe right, you’ll see layers, or ‘beds’, of buff-colouredsandstone and f laky grey shale. Look out for sloping linesin sandstone next to the path (see picture). Known as‘cross-bedding’, these formed when sand was deposited inunderwater dunes in ancient river deltas. Continue along the path for another 50m.

Haydon Bridge DykeLook out for a mossy rib of rock to the right. Close up there’sa small, freshly broken surface (see picture), which is darkand finely crystalline. This is dolerite (or whinstone) and ispart of the Haydon Bridge Dyke which formed from moltenrock around 295 million years ago. This may have been afeeder for the Whin Sill (see description overleaf).Continue along the path, passing the suspension bridge,until you reach a right bend in the river with the cliffs ofRaven Crag on your right.

Shingle banksThis is a good place to find pebbles of differentrocks. Local Carboniferous rocks, especially buff-coloured sandstone, are the most common. Youcan also find grey limestone and dark grey shale.If you are lucky you may spot fossil plant remainsor worm burrows in the sandstone, or whiteshelly fossils in the limestone.

But there are some rocks that could not have gothere by the river alone. Finely speckled smoothgrey cobbles are dolerite from the Whin Sill,brought here from Hadrian’s Wall countryby ice. Greenish grey pebbles are slates andvolcanic rocks brought here by ice fromthe Lake District.Continue along the path past a recentlycollapsed part of the riverbank, nowfenced off.

The Little LimestoneLook down to an area of flat rock in the river. This islimestone, which formed from the limy ooze thataccumulated on a tropical sea floor 320 million years ago.Past miners and quarrymen called this layer the LittleLimestone, to distinguish it from the thicker GreatLimestone beneath it.Cross the bridge and turn right to return to the car park.

Raven CragThese impressive cliffs are made up of beds of sandstonewhich were once layers of sand in Carboniferous deltas.Weathering has picked out features that give clues toconditions 320 million years ago. The beds high in the faceare very thick and probably built up quickly. Lower layersshow fine layering and some cross-bedding (see Stop 1). Continue until just past a junction with a path which joinson the right.

Living fossilsIf you’re here in summer,there’s a stand of gianthorsetails beside the path.These are related to thehorsetails – some up to10m high – that grew inCarboniferous times. Backthen, the rocks at AllenBanks were beingdeposited as sand and mudin vast deltas, which wereperiodically covered inswampy forests.

Lead-tolerant plants As you emerge from woods into a grassyglade, look out for mountain pansiesin late spring and summer. This isone of several species that cantolerate metal-rich soil. Here, theymay be related to nearby lead oresmelting (see next Stop 7).

Ancient woods and past industryBriarwood Banks is an area of ancientwoodland, managed by theNorthumberland Wildlife Trust. By theNature Reserve sign there is anovergrown ruin which was part of anold industrial complex, possibly relatedto lead ore smelting in the 1680s.Cross the bridge over the river and jointhe road at Plankey Mill.

Plankey MillOriginally an 18th-century corn mill,these buildings are built of localsandstone and are roofed with thinsandstone slabs.Follow the road uphill for 100m. Turnleft on to a track, keeping well clear ofthe steep drop to the left.

Roots – past and presentBy the junction there’s an oak tree with gnarledroots growing into rock. Less obvious are thefossil remains of plants in the rock itself. Lookfor black f lecks and streaks in the crumblysandstone – this is carbon from plants that died320 million years ago and were caught up indelta sands. Follow the track past the ruins of Plankey Farmand continue along the path. Descend a bank.

River terraces and floodplainsThis steep bank is the edge of a river terrace, a relictf loodplain from when the river f lowed at a higher level,thousands of years ago. The river has cut down to a newlevel, leaving its old f loodplain high and dry.Continue along the riverside and into woods oppositeRaven Crag.

Fallen blocks and outcropsAlong the path you’ll weave around large mossy blocks ofsandstone which have tumbled from the cliffs above. You’llalso pass outcrops of sandstone, some of which show cross-bedding (as seen at Stop 1).Follow the dark brown waymarkers, eventually descendingto the suspension bridge. Just before crossing the bridgeturn left and follow a path for a short distance and upsome stone steps.

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Fresh surfaceFresh surface

Sandstone

DoleriteDolerite

LimestoneLimestone