Geology

Geology to see in Southern Devon

   10.  Plym Valley Trail
   11.  Plymouth Sound, Shores & Cliffs
   12.  Wembury
   13.  Ivybridge & the Erme Valley
   14.  Blackdown Rings
   15.  Start Point to Prawle Point
   16.  Slapton Ley & Slapton Sands
   17.  Berry Head to Sharkham Point
   18.  Daddyhole
   19.  Kents Cavern
   20.  Hope’s Nose to Walls Hill
   21.  Dawlish Warren & Cliffs

10. Plym Valley Trail

Nearest city: Plymouth
OS grid reference: Cann Quarry SX 524596, Bickleigh Vale Quarries SX 522596.
Management: National Trust & private landowners
National Trust - logo

The Plym Valley Trail is quite a gentle route for both cyclists and walkers heading out from Plymouth towards Dartmoor. Passing through Plym Bridge Woods, managed by the National Trust, the trail offers great views and the opportunity to get close to wildlife, as well as being of interest to the geologist.

© NTPL/Chris King - image
© NTPL/Chris King

In particular, the disused sites of Cann and Bickleigh Vale quarries are worth a look.Both quarries were used to mine slate, with Cann Quarry being worked as far back as 1683.The slate was used in roofing and flooring, though it was markedly inferior to the Welsh product.

The slate was originally a marine mud which, having been buried and turned into mudstone, was heated and compressed as a result of the tremendous forces at work during a collision of tectonic plates.This process altered the orientation of the minerals within the mudstone allowing it to split easily. That is, it had become slate.

Both quarries are cut by a fine grained granite dyke (molten rock which intrudes into the local rocks).This feature is actually known as an elvan dyke,‘elvan’ being an old south-west mining term for granite dykes.

During the breeding season Cann Quarry is home to a pair of peregrine falcons and there is usually a viewing station with telescopes available for use.

Facilities:
There are public facilities and refreshments in Plymouth and car parks at Plymbridge to the south.

Access:
By foot:
Walk along the canal path or the old railway cycle route from the National Trust car park approximately 1 km to the south. Both quarries lie either side of the River Plym, Cann to the east and Bickleigh Vale to the west. Bicycle: Plym Valley Trail National Cycle Network route 27. Road: From Marsh Mills junction of A38 go to Plympton.Turn left onto Plymbridge Road (Plymbridge is in the middle of Plymbridge Road and is closed to through traffic). Bus: A regular service runs between the centre of Plymouth and Colwill road (with 1 change and 800m walk to Plymbridge Road).

Map
© Crown copyright. All rights reserved. 100019783. 2006

Further information: please view www.nationaltrust.org.uk or call 0870 458 4000. Further details on the geology of these sites are available at www.devon.gov.uk/geo-bvq image - PDF icon (330KB - pdf help) and www.devon.gov.uk/geo-caq image - PDF icon (340KB - pdf help).

11. Plymouth Sound, Shores and Cliffs

Nearest City: Plymouth
OS grid reference:
SX 492 497– SX 487 533
Status:
AONB, SSSI, SAC
Management:
Ministry of Defence & private landowners

This magnificent coastal section runs along the eastern side of Plymouth Sound from Andurn Point northwards to Mount Batten Point.As you travel along this route you can experience a varied and impressive geology.The rocks become younger as you head north but all were laid down during the Devonian Period (417 - 354 million years ago), named after this county.

The southernmost outcrops at Andurn Point consist mainly of red and green slates with sandstones that were deposited in lakes and rivers in seasonally arid conditions. Heading north, the dominant rocks are slates, siltstones and sandstones but these are greyer in colour and contain some marine fossils, indicating flooding of a continental edge by the incoming of the sea.

map
© Crown copyright.All rights reserved. 100019783. 2006

At Bovisand Bay the harder Staddon Grits appear and form the headland from Staddon Point northward.The sandstones in this formation were deposited in marine sand bars.To the north,most of Jenny Cliff Bay is cut into softer and younger marine slates but the northernmost promontory of Mount Batten Point is made of limestone laid down in a clear warm tropical sea.

Along most of this coast you can observe dramatic faults and folds in the rocks, sometimes producing a chevron pattern.These give clear evidence of the terrific pressures that were exerted on the rocks during a period of tectonic plate collision between 330 and 300 million years ago.

Access:
Beaches are only accessible at low tide; Crownhill Bay has cliff access to the beach. Road: Site accessed from minor roads leading to the beaches. There is one car park towards the north end of Jennycliff. There is another parking site beside the road leading down to Fort Bovisand to the east of Bovisand. Beach café open during the season. Foot: The South West Coast Path winds along the site. Bus: There is a regular service from Plymouth (Royal Parade) to Turnchapel.

For more information on the geology please view www.devon.gov.uk/geo-psc image - PDF icon (566KB - pdf help).

12. Wembury

Nearest City: Plymouth
OS grid reference: SX 520485 504485
Status:VMCA,AONB,SSSI, SAC q
Management: National Trust
National Trust - logo

This site spans from Wembury Beach west to Wembury Point. This area has been designated an Area of Outstanding Natural Beauty and no visitor can fail to be impressed by the magnificent coastline.

The foreshore and cliffs expose excellent sections of Lower Devonian rocks - mainly red mudrocks, now metamorphosed to slate, siltstones and sandstones.These are thought to have been originally lain down in mudflats and floodplains associated with lakes. Some fossil fish remains have been found here and there may have been an occasional connection between these lakes and the nearby sea. In places, folds in the rock can be seen

© Peter Wakely/Natural England
© Peter Wakely/Natural England

– an indication of the vast forces that have been at work here in the ancient past.

Interestingly, a raised beach platform and a fossilised cliff line can be seen at the back of the modern beach.This is largely covered by a stony deposit (known as ‘head’) formed by downward soil movement during the freeze/thaw conditions of the Ice Age, though at Wembury Point itself some remains of the original beach cobble can still be seen.

Facilities:
The Wembury Marine centre is operated by the Devon Wildlife Trust.

Access:
Foot:
The South West Coast Path and Erme-Plym Trail runs throughout the area. Bicycle: The area is easily accessible by bicycle – close links with the National Cycle Network. Road: Take the A379 at Elburton on the east side of Plymstock and follow signs for Wembury and Wembury Beach. Parking is available at the National Trust car park. Bus: There is a regular service between Plymouth and Wembury.

map
© Crown copyright.All rights reserved. 100019783. 2006

For further information on this site’s geology please visit www.devon.gov.uk/geo-wmp image - PDF icon (420KB - pdf help). For more information on the VMCA please view www.devonwildlifetrust.org and www.wemburymarinecentre.org or call 01752 862538. See also www.nationaltrust.org.uk.

13. Ivybridge & the Erme Valley

Nearest town: Ivybridge
OS grid reference: SX 633 557 – SX 643558 – SX 633589
Management: Private landowners

The areas of Ivybridge Town and the valley of the River Erme to the north and south are very interesting for their geological features.

Exposures in the River Erme north of the railway viaduct show Upper Devonian slates that have been baked by the intrusion of hot granite. Dykes of very fine grained granite (known as aplite) are exposed in the river (at SX 6385 5710) and just above this a sheet-like mass of aplite forms the river bed and is intruded into the slates. Providing the water is not too high, the contact of the main body of the granite with the slates can be seen at SX 6375 5740.

© Dartmoor National Park Authority
© Dartmoor National Park Authority

Of particular interest in this area is a large boulder outwash fan which extends south from the mouth of the Erme Gorge.These boulders were probably deposited during a torrential flash flood during the Ice Age. Part of Ivybridge is built on this fan, and its presence can be witnessed by the use of the boulders as building material in the lower parts of the town, as well as in old field banks in the surrounding countryside.

Facilities:
There are cafes, shops and toilets in Ivybridge.

Access:
Foot:
The area is easily accessed by public footpaths.The Erme Valley trail runs 3 miles along the valley from Ivybridge to the village of Ermington; the route is comprehensively way marked. Bus: There are regular services from Plymouth to Ivybridge. Train: Services from Exeter and Plymouth. Road: Ivybridge is just off the A38 from Plymouth to Exeter. Car parking is available in the town. Bicycle: A National Cycle Network (on-road) route goes through Ivybridge and when completed will connect to Plymouth.

For more information on the geology of this area please visit www.devon.gov.uk/geo-iev image - PDF icon (314KB - pdf help).

14. Blackdown Rings

Nearest town: Kingsbridge
OS grid reference: SX 720520
Status: AONB,Ancient Monument
Management: The Arundell Charity

This site provides a stunning viewpoint showing the broad geological features of the South Hams.

Blackdown Rings consists of an Iron Age hillfort with a Norman motte and bailey castle built within the prehistoric embankment.

The rocks underlying the site, Staddon Grits, can be seen in the commemorative stone by the site entrance.These are harder than the Devonian slates found to the north and south, so resulting in some of the highest land to the south of Dartmoor. Devon’s oldest rocks, those of the Start Complex, are just visible in the distance to the south.

The landforms of the South Hams, seen from this panoramic viewpoint, can be related to the structural trends of the Devonian rocks, which generally follow an east-west orientation. However, this contrasts markedly with the north-south alignment of the deeply-cut valley of the River Avon, which flows nearby.

A permissive path runs northwards into a newly established woodland. Blackdown Rings is also very close to Andrew’s Wood, an attractive Devon Wildlife Trust nature reserve.

Facilities:
There is an information board detailing the archaeological remains found in the area.

map
© Crown copyright.All rights reserved. 100019783. 2006

Access:
Foot:
There is a small car park on site with direct access to the viewpoint and other features. Bus: There is no direct service to the site but there are regular buses from Kingsbridge to California Cross (with a 2000m walk). Road: The site is sign-posted off the California Cross to Loddiswell road at Blackdown Cross.

Further information is provided at: www.devon.gov.uk/geo-blr image - PDF icon (273KB - pdf help). For information on the nearby Andrew’s Wood nature reserve see: www.devonwildlifetrust.org.

15. Start Point to Prawle Point

Nearest town: Kingsbridge/Salcombe
OS grid reference: SX 821376 769356
Status: AONB, SSSI, SAC
Management: National Trust & private landowners
National Trust - logo

Start Point to Prawle Point is a truly beautiful stretch of south Devon coastline. It is underlain by rocks that are very different to those of the rest of Devon.These are known as mica schist,found at Start Point (SX 828372), and hornblende schist, which has a green tint and is found at Prawle Point (SX 772352).

These rocks are the result of intense pressure and heat acting on the original rocks during a collision of tectonic plates.The mica schists were originally shales, siltstones and sandstones, whilst the hornblende schists were once lavas and ashes, all probably of Devonian age.

The area displays good examples of beach platforms including the present wave-cut platform in the intertidal zone.An older beach platform occurs just above the present beach and extends back to an old cliff line. Deposited on this older platform are raised beach deposits which consist of beach sand and cobbles mixed with rock debris, known locally as ‘head’, deposited as a result of rock movement during the Ice Age.

© Peter Chamberlain
© Peter Chamberlain

Facilities:

Parking is available at a National Trust car park at Prawle Point, Lannacombe Beach (very limited parking) and Start Point (parking at an Estate car park).

Access: Foot: The South West Coast Path runs through the site. Please note that is important to stay on the public footpath due to dangerous cliff faces along the site (both above and below the public footpath) and to refer to the safety guidance at the start of this booklet. Please also note that the South West Coastal Path section between Start Point to Prawle Point is quite long (nearly 6 miles). Road: The site can be accessed from the A379, via numerous minor roads (easiest access is via minor roads to Prawle Point).

map
© Crown copyright. All rights reserved. 100019783. 2006

For further details please view www.nationaltrust.org.uk or call 0870 458 4000. More detailed geological information is available here www.devon.gov.uk/geo-psp image - PDF icon (1.29MB - pdf help).

16. Slapton Ley

Nearest town: Kingsbridge
OS grid reference:
SX 835 455 - 845 466 Status: AONB, SSSI, NNR
Management: Field Studies Council
Field Studies Council - logo

The key geological feature at this wonderful site is a dramatic shingle bar running from Strete Gate south to the village of Torcross. Known as Slapton Sands, it separates the sea from an important freshwater lagoon, Slapton Ley.

© Peter Wakely/Natural England
© Peter Wakely/Natural England

The ridge is made up of flint, chert and quartz pebbles, some of which are stained red. It is probable that the major formation of this barrier began about 5000 years ago, during a period of sea level changes.As the sea rose the water transported the shingle ridge ahead of it.This linked the headland at Strete Gate with Torcross, damming a post glacial estuary and forming the freshwater lagoon.The sediments that have accumulated in the lagoon now form an important record of environmental changes since the formation of the ridge.

Replenished with shingle by long shore drift of debris derived from cliffs and from sediments on the sea floor, the ridge remains a dynamic structure and is vulnerable to the power of the sea. Indeed, the road that runs along the ridge has recently had to be realigned.

However, a still more dramatic example of the power of the sea is demonstrated some way to the south, at Hallsands.This fishing village was once protected by a pebble ridge. However, offshore banks focus wave energy at this point and this, perhaps combined with intertidal dredging to acquire materials for the construction of naval dockyards near Plymouth in the late 19th century, led to large scale erosion. In particular, a series of storms in 1917 had devastating effect and by the end of September that year only one house remained habitable.

The ridge and lagoons at Slapton Ley are of national importance for their wildlife, including important communities of plants and breeding and passage birds.

Facilities:
Refreshments are available in Slapton and other local villages.There are toilets and picnic sites at the A379 car parks.There is a field centre,a bird hide and access to guided tours on site.

Access: Bus: There is a regular service between Slapton and Dartmouth, Kingsbridge and Plymouth. Road: Slapton is adjacent to the A379 and Slapton Ley can be accessed by minor roads from the A379. Parking can be a problem in Slapton so it is advisable to use car parks along Slapton Sands. Foot: The site is on the South West Coast Path. Bicycle: The nearest route is Route 28 of the National Cycle Network.

map
© Crown copyright.All rights reserved. 100019783. 2006

For more information on the geology of the shingle ridge, please view www.devon.gov.uk/geo-sll image - PDF icon (340KB - pdf help). Further information on the wildlife of Slapton Ley may be viewed at www.slnnr.org.uk.

17. Berry Head to Sharkham Point

Nearest town: Brixham
OS grid reference: SX 941564
Status: AONB, SSSI, NNR, SAC, Ancient Monument
Management: Torbay Coast and Countryside Trust
Torbay Coast and Countryside Trust - logo

This dramatic stretch of coastline is of tremendous geological, historical, ecological and landscape importance.

Berry Head is a large headland of Devonian age limestone providing an excellent viewpoint from which to admire Torbay’s varied geology and beautiful coastline. Soaring to a height of 195m, it is generally flat topped, with a series of cliffs, steep slopes and ledges reaching down to the sea. This limestone was deposited as part of a reef in a tropical sea and is exposed in old quarries at the top of the cliff on the northern side of the site. These provided material for the Napoleonic fortifications that are still well preserved at Berry Head.At Shoalstone Beach wave cut platforms have exposed two sets of red sandstone sedimentary dykes. Some of these are lined with large sparry calcite crystals.

From Sharkham Point it is possible to look back at the impressive cliffs made of limestone and mudstone and see signs of folding. Iron mining used to take place at Sharkham Point, just to the north of the point itself. Besides its use in the production of iron, the haematite ore was powdered and formed the basis for an anticorrosion paint.

The link between geology and wildlife is clearly demonstrated along this stretch of coast. For example, there are large areas of species-rich limestone grassland, containing a number of rare

© Paul Glendell/Natural England
© Paul Glendell/Natural England

plants, and different rates of erosion of the cliffs of Berry Head have created a series of ledges which are now home to the largest breeding colony of guillemots on the south coast of England.

Facilities:
There are toilets and a café at Berry Head.A visitor centre is open from Easter to late October and an unmanned information point is open all year.

Access:
Foot:
The South West Coast Path runs through the site. Please do not get too close to the cliff edges and refer to the safety notes at the start of this booklet.There is some easy access path at Berry Head. Train and bus: There is a mainline train station at nearby Paignton and bus services operate from here to Brixham. Road: Access is via the A3022 and the A379. Car parking is available at Berry Head and Sharkham Point. Boat: One of the best ways to view the geology of this coastline is by boat and cruises are available along this coast from Torquay, Paignton and Brixham Harbour.

For further information on this site and details of events, please view www.englishrivierageopark.org.uk, www.devon.gov.uk/geo-bsp image - PDF icon (690KB - pdf help), and www.countryside-trust.org.uk or call 01803 882619.

18. Daddyhole

Nearest town: Torquay
OS grid reference: SX 927628
Status: SSSI
Management: Torbay Coast and Countryside Trust
Torbay Coast and Countryside Trust - logo

The coastal headland comprises impressive coves, cliffs, foreshore and quarry exposures. Daddyhole Cove, together with a small quarry at Triangle Point to the north-east (accessed via Meadfoot Beach), shows a superb example of limestone from the Devonian period. Underlying the limestone are fine-grained sedimentary rocks known as shales. Two features of the site are of particular interest. Firstly, it exhibits dramatic arch-shaped folding of the rocks. Secondly, the site has yielded many fossils, particularly at the transition between the limestone and the shales.These include fossilised corals and brachiopod shells (marine invertebrates) important in interpreting the palaeoecology of the Middle Devonian period.

At the western end of the cove there is a good example of landslip and rockfalls but please be careful when exploring and follow the safety guidance at the start of this booklet.

Facilities:
Beach café, toilets.

Access:
Foot:
The South West Coast Path runs through the site, from Torquay Harbour follow Parkhill Road. Train and Bus: Main line train station nearby and bus services run from Exeter and Plymouth to Torquay. Road: The site lies east of Torquay Harbour and is accessed by the Meadfoot Sea Road. Parking is available. Boat: One of the best ways to view the geology of this coastline is by boat and cruises are available along this coast at Torquay, Paignton and Brixham Harbour.

map
© Crown copyright.All rights reserved. 100019783. 2006

For further information on this site, please view www.englishrivierageopark.org.uk or please call 01803 606035 or view www.devon.gov.uk/geo-dad image - PDF icon (618KB - pdf help).

19. Kents Cavern Admission charge applies

Nearest town: Torquay
OS grid reference: SX 934641
Status: SSSI,Ancient Monument
Management: Kents Cavern Ltd.
Kents Cavern Ltd. - logo

Kents Cavern is fascinating for both its geology and human history. It boasts beautiful and spectacular geological formations and significant prehistoric finds, including flint hand-axes dating from over 450,000 years ago. Indeed, it is one of the oldest recognisable human occupation sites in Britain.The oldest human bone ever found in Britain was discovered in Kents Cavern, a jawbone dated at 3740,000 years old. Scientific research is on-going to discover if the bone is from a Neanderthal or a modern human.

The caves are within the Devonian limestone and were formed by water erosion over millions of years. Interestingly, whilst the limestone is naturally white much of Kents Cavern appears reddish-brown due to the iron oxide contained in the material above (similar to the south Devon soil). Some of the most notable geological features are formations of calcium carbonate also known as calcite.These include impressive stalagmites (growing from the floor). Kents Cavern has yielded some important fossil remains including such remarkable creatures as sabre-toothed cat, cave bear, mammoth and woolly rhinoceros. Many of the larger bones clearly show the marks of hyena teeth.

Facilities:
Restaurant, shop, licensed bar and guided tours.

Access:
Foot:
From the South West Coast Path leave the path near the Palace Hotel. Bus: Services run from Exeter to Wellswood. Road: Follow the A380 from Exeter to Torquay harbour and then follow the brown tourist signs.

© Kents Cavern Ltd
© Kents Cavern Ltd

For further information and details of opening times and admission charges visit www.kents-cavern.co.uk or call 01803 215136. Further geological information is available at www.englishrivierageopark.org.uk and www.devon.gov.uk/geo-kec image - PDF icon (429KB - pdf help).

20. Hope’s Nose to Walls Hill

Nearest town: Torquay
OS grid reference: SX 932654 – SX 947635
Status: SSSI
Management: Torbay Coast and Countryside Trust
Torbay Coast and Countryside Trust - logo

This impressive stretch of coastline can be easily accessed from Torquay and demonstrates some important geological features.

The main rock here is Devonian limestone and this can be seen in some excellent exposures. Some of these display abundant collections of fossil animals, including well preserved corals - evidence of times when Torbay was located south of the equator and bathed in shallow tropical seas. Other notable

© Still Imaging
© Still Imaging

features of the site, particularly on the eastern side of Hope’s Nose, are a number of distinct mineral-rich veins. It is the only known location in Britain for the assemblage of minerals present, including native gold and rarities such as palladium (a metallic element that resembles platinum).

On the southern side of Hope’s Nose, and also on the nearby Thatcher Rock, raised beaches can be seen about 6m above present day sea levels.These are very rich in fossil marine molluscs, with 17 species present at Hope’s Nose, and no fewer than 43 species at Thatcher Rock.These beaches tell a story about past sea-level change and date from a warm interglacial period in the Ice Age when the seas were much higher than today.

A large fold can also be seen in the limestone at Hope’s Nose which is the result of earth movement under great pressure caused by tectonic plate collision.

The coastline from Hope’s Nose north to Walls Hill well demonstrates the connection between geology and wildlife and is of national importance for its limestone woodlands and species-rich grassland.

Facilities:
There are a number of parking areas along the coastal section.

map
© Crown copyright.All rights reserved. 100019783. 2006

Access: Foot: The South West Coast path runs through the site. Bus and Train: There are regular services from Exeter to Torquay. Road: Follow the A380 from Exeter to Torquay. From Torquay Harbour follow Meadfoot Sea Rd to Ilsham Marine Drive. Boat: One of the best ways to view the geology of this coastline is from the sea and cruises are available from Torquay, Paignton and Brixham Harbour.

For further information and details of events on this site, please view www.englishrivierageopark.org.uk, www.countryside-trust.org.uk or please call 01803 606035. Also, further geological details are available at www.devon.gov.uk/geo-hwh image - PDF icon (1.03MB - pdf help).

21. Dawlish Warren & Cliffs

Nearest town: Dawlish
OS grid reference:Warren -SX 985793; Cliffs - SX 977778
Status: LNR, SSSI, NNR, SAC, SPA
Management: Teignbridge District Council (the Warren)
Teignbridge District Council - logo

Dawlish Warren is a fascinating place. This sand spit at the mouth of the Exe Estuary is not only of geological interest but is also a nationally important habitat for a wide variety of plants and animals. It also has a protective effect on the estuary and helps to prevent localised flooding.

Dawlish Warren is a rare ‘double sand spit’ with two dune ridges that, in the recent past, were separated by a tidal inlet.The two ridges can still be seen, most clearly from the meadow known as Greenland Lake. The Warren is also unusual because it is an acidic sand spit and is not derived from shell material.

Compared to most sites of geological interest, Dawlish Warren is very young – a mere 7000 years old! It was created by post glacial sea level rises.As might be imagined, a sand spit is not the most stable of structures and its continued presence relies on a balance between erosion on the one hand and the arrival of sediments that travel along the coastline in a north-easterly direction (longshore drift). The wind has also had a significant effect on

© Craig Dixon
© Craig Dixon

the Warren, with sand dunes visible in the exposed areas facing the open sea. The more sheltered area behind the spit has developed an area of intertidal sand and mud that provides feeding grounds for wintering wildfowl and waders. The Warren continues to evolve and in recent decades storms and higher tides have resulted in an overall loss of sediment.

Nearby to the south-west can be seen the impressive Dawlish Cliffs. They show some of the finest exposures of Permian sands in Britain and their red colouration is a striking feature of the coastline.Ancient winds piled up these sands upon what was a gravelly desert floor and you are, in effect,looking at fossilised sand dunes. The modern effect of wind erosion on these cliffs has produced some striking patterns and forms in the exposed sand.

Facilities:
Nearby parking, shops and cafes. Cycling is not permitted within the reserve at Dawlish Warren, where dog restrictions also apply all year round.

Access: Train: Direct services from Exeter and Plymouth. Bus: Regular bus services run to Dawlish Warren from Exeter. Road: Leave the M5 Motorway at junction 30 and follow signs for Dawlish along the A379.

For further information please view www.teignbridge.gov.uk, www.devon.gov.uk/geo-dww image - PDF icon (900KB - pdf help) and www.devon.gov.uk/geo-dwc image - PDF icon (685KB - pdf help).