Jncc coastal Directories Project Region 11 The Western Approaches

holiday is catered for around the whole of the Mount’s Bay
area on the south coast, and at St. Ives and Newquay on the
north Cornish coast, Minehead and Burnham on the
Somerset coast and Penarth, Barry and Porthcawl in Wales.
Elsewhere also a wide range of facilities exist, including golf
courses, theme parks and marinas, and activities such as
rock climbing (for example at Land’s End), walking, sand
yachting (the Severn) and natural history study are popular.
Offshore the variety is equally diverse, with beach and sea
angling, water skiing, jet skiing, canoeing and yachting, and
the region has some of the best surfing beaches in Britain.
The importance of this region for the conservation of the
natural environment and the archaeological heritage,
coupled with present-day human use and enjoyment, make
coastal management an important issue.  Many initiatives in
the region are addressing the need for integrated
management, including the South West Regional Planning
Conference, the various Heritage Coast Services and the
Standing Conference of Severnside Local Authorities
(SCOSLA).
1.2.6  Further sources of information
A.  References cited
Pye, K., & French, P.W.  1993.  Erosion and accretion processes on
British saltmarshes.  London, Ministry of Agriculture, Fisheries
and Food.  
B.  Further reading
Davidson, N.C., Laffoley, D.d’A., Doody, J.P., Way, L.S., Gordon, J.,
Key, R., Drake, C.M., Pienkowski, M.W., Mitchell, R.M., & Duff,
K.L.  1991.  Nature conservation and estuaries in Great Britain.
Peterborough, Nature Conservancy Council.
Robinson, A., & Millward, R.  1983.  The Shell book of the British coast.
Newton Abbot, David and Charles.  
Steers, J.A.  1973.  The coastline of England and Wales.  Cambridge,
Cambridge University Press.
Region 11  Chapter 1  Overview
18
The geology of the Lizard is unique in southern Britain.  Originally part of an ancient ocean floor, the rocks of which it was formed were
thrust to the surface more than 400 million years ago.  These rocks have eroded at different rates, creating a coast of great complexity and
savage beauty.  The thin, ultra-basic soils of the peninsula harbour some of the country’s rarest flowering plants.  Photo: Pat Doody, JNCC.

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2.1.1  Introduction
The region covers the south-westernmost tip of Cornwall,
the whole of the southern coast of the Bristol Channel and
much of the inner channel’s northern coast.  The north-
western coast of Devon and Cornwall in particular abounds
with localities of great geological interest.  From the
southernmost coast of Cornwall to Minehead the coast is
composed of a range of Devonian and Carboniferous rocks
arranged in a structurally complex assemblage of folds, and
intruded by dykes, sills and granite domes.  The structural
‘grain’ of the region, reflected in the orientation of the major
and minor folds, is east-west, although the folds are cut by
NW-SE faults which had a history of movement until at
least the mid-Tertiary.  The main granite body of Devon and
Cornwall forms an almost unbroken batholith at depth,
extending from Dartmoor to the Isles of Scilly and reaching
the surface in several places.  East and north of Minehead,
structurally simpler and younger Triassic and Jurassic rocks
are exposed along the coast, with local outcrops of
Carboniferous and older rocks seen in anticlinal cores (the
eroded tops of folds) (
Map 2.1.1
; 
Table 2.1.1
).  
Mesozoic sedimentary basins lie offshore (see also
section 2.2.3
), but these sediments reach land only along the
inner Bristol Channel.
Much of the detailed geomorphology of the coast is
determined by the resistance of the rocks to marine erosion.
The softer shales and slates form bays, coves or clefts
according to the scale of their exposure, while the more
massive rocks form pronounced headlands or steep cliffs.
Intrusion of the granites has locally altered the rocks
surrounding them and given rise to mineralised veins.  
Tin is an important economic mineral in the region, and in
places the rocks contain a diverse suite of unusual minerals.
The region lay to the south of the late Devensian ice
sheet, though a tongue of ice extended south from the Celtic
Sea to reach the Isles of Scilly.  Glacial deposits are therefore
almost absent from the coast, although isolated erratics and
19
Chapter 2  Geology and physical
environment
2.1  Coastal geology
British Geological Survey
Table 2.1.1  
Geological column
Era
Period
Epoch
Age of start
Stratigraphic units 
Significant geological events
(million yrs)
mentioned in the
text
Cenozoic
Quaternary
Holocene
0.01
Pleistocene
1.6
Periglacial conditions, fluctuating
sea-levels
Tertiary (Neogene)
Pliocene
5.1
St. Erth Beds
Miocene
25
Tertiary (Palaeogene)
Oligocene
38
Eocene
55
Palaeocene
65
Emplacement of Lundy granite
Mesozoic
Cretaceous
144
Jurassic
213
Lias
Marine deposition
Triassic
248
Rhaetic
Mercia Mudstone
Deposition of non-marine
‘continental’ sediments
Palaeozoic (Upper)
Permian
286
Deposition of non-marine
‘continental’ sediments
Carboniferous
360
Emplacement of granites, 
Variscan Orogeny
Devonian
408
Mylor Slates, 
Variscan Orogeny,
Meadfoot Beds
marine deposition
Palaeozoic (Lower)
Silurian
438
Ordovician
505
Cambrian
590
Precambrian
Note: shaded boxes show ages of rocks with important or extensive exposures in the region.

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