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Geology and
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12
Geology and minerals
Introduction
12.1
Edinburgh’s underlying geology has shaped its landscape and setting which in turn has influenced
the nature and form of the city’s built environment. It has helped to make it an attractive city in
which to live and work, and one which attracts thousands of visitors each year.
12.2
The city is said to have been built on seven hills, the first to be developed being the Castle Rock
on which Edinburgh castle sits. The development of the ‘New Town ’in the 19th and 20th
centuries saw Calton Hill followed by the other six hills being absorbed into the city. Most of
these landforms are volcanic in origin and were subsequently affected by erosion, in particular
owing their current form to glacial moulding.
12.3
Because of their height the Pentland Hills, while mostly outside the city boundary, dominate
views to the south. To the north the city overlooks the the Firth of Forth, a broad sea inlet.
12.4
While some underground mining took place in Edinburgh in the past, most large scale activity
took place outside the city. The thick sequences of carbon-rich sedimentary rocks which
underlie Edinburgh and the Lothians has been a source of oil, gas and coal. The oil shale
industry was an important part of the West Lothian economy until the 1960s. While no deep
mines are now operational in central Scotland, a limited amount of open-cast coal mining takes
place in Midlothian.
12.5
Stone for building, aggregate and lime has been extracted throughout the area, although in
Edinburgh this is limited to the quarrying of a small amount of hard rock on the city’s west side.
Modern limestone extraction for cement takes place near Dunbar in East Lothian.
12.6
While geology has helped to underpin the city’s success, contributing to its wealth and prosperity,
it has also had a number of negative impacts. Many of the city’s historic buildings which were
constructed from locally quarried sandstones are now in a poor state of repair and require urgent
attention. Because the original sources of stone are no longer available, carrying out repairs is
often a problem due to the lack of suitable matches from quarries outside the Lothians.
12.7
Edinburgh’s mining legacy and other factors have caused ground stability problems in parts of
the city where building settlement is a major problem.
Geology
12.8
The rocks underlying the Edinburgh area are typical of those found in the geological heartland of
Scotland, the Midland Valley. These belong to two main geological periods : the Devonian and
the Carboniferous, covering a time span from about 415 million years ago to about 300 million
years ago. The area has also been affected by Quaternary glacial activity (2 million years to
present).
12.9
The geographical distribution of the rocks referred to above is shown in Map 1. The geological
divisions are illustrated in Table 1.
Map 1: Geology of Edinburgh and the Lothians
source : Lothians Landscape Character Assessment, 1998 (Scottish Natural Heritage / Ash Consulting)
Table 1: Geological Divisions
Devonian
12.10 The oldest rocks in the Edinburgh area are Devonian age (ca. 415 M years old). Lower
Devonian lavas including basalts, andesites and acid lavas and tuffs were produced by volcanoes.
These deposits formed the Pentland Hills, Braid Hills and Blackford Hill.
Carboniferous
12.11 The Lower Devonian rocks were unconformably overlain by a sequence of sedimentary rocks
including conglomerates from alluvial fans, red continental sandstones (typically seen in the
Craigmillar and Dreghorn areas) and coastal plain siltstones and mudstones (referred to as the
‘cementstones’ of central Edinburgh). All these were laid down in a semi-arid climate.
12.12 Most of the rocks in the Edinburgh area are Carboniferous in age (365-290 m years old). The
region was volcanically active during the early Carboniferous period, around 350 million years
ago. The small volcanoes of Arthur’s Seat and Calton Hill, Castle Rock and West and East
Craiglockhart were briefly active, laying down lava flows and volcanic ash. At various times
subsequently, molten rock was also intruded between layers of sedimentary rock to form igneous
sills of dolerite, the best example being Salisbury Crags. These also form other prominent
landforms such as Corstorphine, Mons, Craigie and Dalmahoy hills.
12.13 The younger sedimentary rocks were formed by the erosion of the remnant mountains as far away
as Scandinavia which were deposited on plains with rivers, shallow lagoons and seas. The
period was characterised by rapidly changing environments, leading to alternating layers of rock.
12.14 During two eras extensive peat mires formed from the luxuriant and fast growing tropical
vegetation that thrived in a ‘greenhouse environment’. These coal forests gave rise to thick coal
seams in sequences known as the Limestone Coal Formation and the Coal Measures. Methane
and carbon dioxide gas are usually associated with coal seams and were sometimes problematic
during past mining activity. Parts of the city underlain by coal and oil shale bearing rock have
been considered moderately prone to gas emission and oil seep.
12.15 Tropical seas encouraged thick limestones to form with corals, shells and sea-lilies as in the
Lower Limestone Formation. The Balm Well at Liberton and St Bernard’s Well at Stockbridge
illustrate the minor pollution of groundwater by oil and gas seepage from the West Lothian oilshale formation. Oil-shales were deposited by massive algal blooms in lakes. Some sandstones
were laid down along coastal beaches; most were deposited by rivers and in deltas - some
containing trees carried down by the floods. Thick, hard, fine-grained sandstones such as
Craigleith and Hailes, which were used as building stones, were formed during this period.
12.16 At the end of the Carboniferous period no further rocks are known to have been laid down in the
Edinburgh area, which remained as land from the post-Carboniferous mountain-building to the
present day. However, massive compressive forces produced by the collision of ancient
continents crumpled and uplifted the sedimentary and volcanic strata. The rocks, previously
horizontal, were tilted and folded into basins, arches and domes, and when the stresses became
too great, they were fractured and faulted. As a result of this phase of activity, the
Carboniferous rocks occupy broad tracts trending roughly north to south. In the west they dip
gently to the west beneath areas of farmland; in the east they dip steeply to the east from the
Lower Devonian lavas of the Pentlands (and the Pentland Fault).
Quaternary
12.17 Like most of northern Britain during the last 2 million years, Edinburgh has been repeatedly
buried under an ice cap hundreds of metres thick. The latest melted as recently as 15,000 years
ago. As each ice-age began, ice built up in the Highlands and Southern Uplands, merged in the
Midland Valley and flowed generally eastwards across Edinburgh. The weight of the ice
selectively eroded the softer sedimentary rocks, leaving the harder volcanic rocks accentuated as
hills. All these hills have a ‘tail’ to the east (lee) side forming a feature known as a ‘crag and
tail’; the best examples being Edinburgh Castle and the Royal Mile and Blackford Hill.
12.18 The ice sheets left extensive areas of glacial debris called till or boulder clay, a mixture of tough
clay, rock flour made from ground-down mudstone and siltstone, together with rounded pebbles
and boulders of sandstones, lavas and dolerite. This was deposited on much of the low-lying
ground. Exceptionally on the south side of the city, by the bypass at Straiton, thick deposits of
sand and gravel are overlain by glacial till. A late resurgence of ice re-advanced across this
area.
12.19 Long, oval ridges called drumlins fashioned by ice cover much of western Edinburgh. The ice
also left scratches (striae) on the harder rocks as a record of its passage. Glaciated ‘pavements’
are visible on Corstorphine Hill.
12.20 Between ice-ages and following the last ice-age, warmer spells allowed the ice to melt, producing
vast amounts of water. This cut new channels to lower ground such as the Hermitage of Braid.
The meltwater carried large amounts of sediment, the coarser parts of which were deposited as
bedded sand and gravel e.g. in Fairmile Park; the finer parts as silts and clays.
12.21 Postglacial lakes (or lochs) also existed. These took the form of hollows formed in the ice
scoured landscape into which water flowed. All except Duddingston Loch have been drained or
filled naturally with clays, silts and sands, their former locations being marked by alluvial flats.
The largest lochs were at Corstorphine, Gogar and Turnhouse. The Borough Loch is now the
Meadows, the Nor’ Loch became Princes Street Gardens. Stream sediment analysis carried by
the BGS in 1995 showed that these contained four times the national average concentrations of
potentially harmful elements (As, Cd, Cu, Pb, Zn) in parts of the city.
12.22 Sea levels have risen and fallen several times since the end of the ice-age due to the ice taking
water from the oceans and the weight of it pressing down on the land which later rebounded
(‘isostatic recovery’). Falling sea levels caused some rivers to cut deep gorges in the rocks e.g.
the River Almond and Water of Leith, where landslip and rockfall still occur. In the Forth
Valley, local sea level was high (about 40 m OD) as the ice retreated. Consequently, raised
beaches formed and estuarine deposits accumulated inland of the present coastline.
Economic Geology
Building Stones
12.23 The predominant building stone in Edinburgh is sandstone. This was quarried most recently at
Hailes, Redhall, Ravelston, Craigleith and Craigmillar. Craigleith was the largest and best
known of Edinburgh's quarries having a world-wide reputation for producing building stone of
the highest quality. It provided most of the building stone for Edinburgh's New Town in the
18th and 19th centuries, and exported stone to London, Europe and the United States. The
quarry was active for over 300 years and the final massive hole had faces 110 metres (360 feet)
high. Filled with inert waste in the 60 years after quarrying ceased, it has now become the
Craigleith Retail Park, opened in 1993.
12.24 Between 1835 and 1865, several fossils of the giant tree (Pitys withamii) were discovered within
the quarried sandstone at Craigleith. The largest, known as the Craigleith Tree, is now on
display in the Royal Botanic Gardens, Edinburgh. To commemorate the discovery of the fossils,
the wall by the doorway to Sainsbury’s supermarket in the retail park has been embellished with
carvings of Carboniferous tree stems and leaves. Along the pavement are planted a row of the
primitive tree, Dawn Redwood (Metasequoia glyptostroboides), once thought to be extinct and
only known from fossils, but found growing in China in 1941.
12.25 The advent of canal, rail and finally road transport allowed stone to be carried from further afield,
including from the west of the city at Binny, Humbie and Dalmeny. As many Scottish quarries
closed, sandstones were brought from quarries in the north of England e.g. from Doddington near
Wooler. Modern buildings in the city are commonly clad with marble, limetone and granite
(polished) but the stone is not sourced locally.
12.26 Research carried out by the BGS in collaboration with Historic Scotland and the Edinburgh
World Heritage Trust examined previous repairs to over 90 buildings in the Edinburgh New
Town. This area, part of a UNESCO World Heritage Site, is an important commercial and
residential area within the city. The study showed that the use of inappropriate materials for
repairs can result in further damage, and makes recommendations for improved decision-making
in the selection of stone for repairs. The work was published in 2004 by Historic Scotland as a
Research Report.
Mining
12.27 Much of the mining which has taken place in Edinburgh occurred prior to the point at which it
was a legal requirement to keep accurate plans of the extent and distribution of mines. The
absence of mine abandonment plans causes difficulties and often it is only following an event
such as an incidence of subsidence that investigations reveal the extent of mining in an area,
although the distribution and extent of quarries sometimes gives an indication of the likely
distribution of underground mining. The British Geological Survey holds a database which
contains details of old mineral workings (see Map 2 which shows locations in Edinburgh). A
table listing quarries and former quarries, as identified on large scale Ordnance Survey maps of
Edinburgh, is attached as an Appendix to this chapter. Many are very small, and in many cases
there is little if any visual trace of the former activity on these sites.
12.28 The ‘Midlothian Coalfield’ has been worked extensively for coal from the surface and by deep
mining since medieval times. Deep coal mines were formerly located at Gilmerton,
Newcraighall and Niddrie within the city boundary.
12.29 Limestone was also quarried and mined from the 17th century until the 1960’s. The extraction
by both quarrying and mining in the Gilmerton area is amongst the earliest examples of such
activity recorded in the Lothians. The ‘Gilmerton Limestone’ seam was commercially
important for producing lime which was used for iron-making and for making mortar.
Limestone seams cross south-east Edinburgh, running broadly in a south-west to north-east
direction, in close association with coal. The ‘Burdiehouse Limestone’ which lies about 420
metres below the Gilmerton Limestone was also mined and quarried extensively in the
Gilmerton-Straiton area and the adjacent part of North Midlothian.
Map 2 : Mineral Sites in Edinburgh
source : British Geological Survey
12.30 Where minerals lay close to the ground surface, the most economical method of extraction was
quarrying, and quarries were established at several locations in the Gilmerton area. A method of
mining commonly adopted in the area was the ‘stoop and room’ technique, also known as ‘room
and pillar’ or ‘pillar and stall’. Tunnels were driven into the seam from several points along the
quarry face, to the full 3 metres height of the workable material. These were connected at
intervals with further tunnels driven at right angles to the first set of tunnels, creating in plan view
an irregular rectilinear grid. The rock between the tunnels was left in place as pillars to support
the overlying rock.
12.31 Because of the thickness and perceived strength of the over-lying strata, and the value of the
mined material, up to 90% of the area of the seam was mined, leaving just 10% as pillars.
Historical accounts suggest that such mines may have been developed by initially leaving wide,
relatively safe, pillars but then reducing their circumference by further extraction in the final
period before the mines were abandoned. This would inevitably reduce the stability of the
overlying rock layers making later subsidence a serious possibility.
12.32 Two types of subsidence would normally be expected above room and pillar mining. In the first
of these, the roof between adjacent pillars can fail in time. As the overlying rock falls into free
space, it tends to increase in bulk, and so it can eventually block and stop the failure. In this
way the effect of failure and subsidence decreases as the failure moves up towards the surface.
Thus the deeper the mine workings, the less the amount of subsidence occurs on the surface. In
the second type of subsidence, the rock falls into a void which is big enough to accommodate all
the debris, and a void migrates as a chimney to the surface. Normally this occurs over
intersections of rooms in the mine, and above relatively shallow mines.
12.33 In November and December 2000, a series of ground settlements in the Ferniehill area of southeast Edinburgh caused by the progressive collapse of long-abandoned underground limestone
mines which had been worked from the face of former quarries, resulted in serious damage to a
number of houses. No residents were injured, but they had to be evacuated at short notice and
33 properties had to be demolished immediately. Other houses also had to be vacated and
demolished, displacing the residents of a further 189 homes.
Hard Rock
12.34 Quarrying for hard rock (mainly the intrusive igneous rock known as dolerite) for use in the
construction industry takes place at a number of locations, mainly in rural west Edinburgh (see
Map 2). A significant proportion of these deposits lie under parts of the Green Belt, Areas of
Great Landscape Value, wildlife sites and SSSIs, prime quality agricultural land, areas of
archaeological significance and historic and designed landscapes. While this may have a
potential effect on the landscape it also means that there is little conflict with other development
which would preclude future mineral extraction as these areas are already protected by various
national and local policies. Potentially, new technology could be available in the future which
would allow extraction in such areas where at the moment it would not be environmentally sound
to do so.
12.35 The Environment Act 1995 included a requirement for mineral planning authorities to review old
planning permissions granted in the period 1948 to 1982. These provisions were subsequently
consolidated in section 74 and Schedules 9 & 10 of the Town and Country Planning (Scotland)
Act 1997. A distinction was drawn up between active and dormant mineral workings. For
dormant sites, no minerals development may be lawfully carried out until such time as a new
scheme of conditions has been submitted to, and approved by the planning authority. For active
sites, the review was progressed in 2 successive three-year phases.
• Phase 1 sites are those where the predominant permission was granted between 1948 and
1969, but also includes sites within various designated areas of scenic or nature conservation
interest
• Phase 2 sites are those where the predominant permission was granted between 1969 and
1982
12.36 In a review carried out by the Council in response to this classification, three active or operational
quarries were identified :
• Hillwood, Ratho (not currently in production) (Tarmac Ltd.)
• Bonnington Mains (Russell RMC)
• Ravelrig (Tarmac Ltd.) 1.2 km. west of Balerno
In January 2008 Tarmac submitted a planning application to extend Ravelrig Quarry to the west,
south and east. If approved, this would extend its productive life from 2009 to 2019, yielding
high quality aggregates for the construction industry. When production has ceased, the owners
propose to restore the quarry to form a nature reserve, with footpaths and public access facilities.
The reserve would incorporate a diverse range of wildlife habitats, including a new loch,
woodland, scrub, grassland, rocky outcrops, and cliff faces.
12.37 A further three sites were categorised as ‘dormant’ in the Council review :
• Craigiehill
• Torphin
• Craigpark
12.38 Planning consents at Craigpark and Torphin quarries have now lapsed. It is proposed to restore
Torphin for recreational purposes, the area having been identified as a local nature conservation
and RIGS site. Craigpark Quarry has a valid planning consent for housing.
12.39 Some examples of quarries which are no longer operational and are being used for other purposes
include :
• Ratho Quarry now accommodates the ‘Edinburgh International Climbing Arena : Ratho’, the
world’s largest indoor climbing arena
• Braehead Quarry is a civic amenity site near Cammo
• Hailes Park (former quarry and landfill site) to become a new greenspace project being
undertaken by a trust on behalf of CEC
12.40 Crushed rock and other materials such as sand and gravel are important sources of aggregates, a
steady supply of which is required to support the construction of new buildings and any
associated infrastructure. The recycling and reuse of construction waste and the promotion of
renewable energy alternatives may result in a future reduction in demand for primary mineral
resources.
12.41 Scottish Planning Policy SPP4, ‘Planning for Minerals’, which was published by the Scottish
Executive in Sept 2006 says that the new city region authorities, which will prepare strategic
development plans (replacing structure plans) should maintain a minimum 10 year supply of
construction aggregates to ensure continuity of supply, subject to other planning considerations.
Other mineral activity
12.42 Other historical mineral activity includes:
• Oil shale extraction (Queensferry area)
• Clay (Portobello and Granton areas) in connection with pottery making
• Sand and gravel (New Hailes, Mortonhall, Fairmile)
Hydrogeology
12.43 As already indicated Edinburgh has a wide range of sedimentary and igneous rocks which show a
variation in their water bearing capacity. However, only a small proportion of rain water soaks
into the ground and enters the groundwater system where it is held within rocks or sand and
gravel deposits. Anthropogenic barriers such as asphalt roads and surfaced pavements
combined with drains and storm water and naturally occurring materials such as boulder clay
each form a barrier to infiltration.
12.44 Within the city there are four main types of aquifer, though none are comparable with the highly
productive aquifers located in other parts of Scotland.
12.45 The first type of aquifer may be found in the Devonian volcanic rocks of the Pentland Hills and
the smaller volcanic hills of the Carboniferous where the rocks have a tight crystalline structure
which have a low porosity and are relatively impervious to water. Therefore any small amounts
of water in these rocks are limited to faults, cracks and fissures. These may be seen as seepages
from rock faces eg. Arthur’s Seat, Castle Rock, and springs / wells on Corstorphine Hill.
12.46 A more important source are the early Carboniferous red sandstones which are seen in exposures
along the city by-pass and are present beneath Craigmillar and parts of the city centre. These
rocks which are relatively porous and permeable were exploited by many breweries in the 18th
and 19th centuries as a good source of brewing water. The Grassmarket, Holyrood and
Craigmillar areas were considered more favourable than others for obtaining good supplies from
deep well and boreholes, although most of these sources are now disused. The sandstone
aquifers are classified as being in the range moderately to highly vulnerable to pollution
depending on the permeability of the rock and thickness of the clay or mudstone cover.
12.47 Carboniferous silts and mudstones underlying much of the west and north sides of the city are
interbedded with sandstones of varying thicknesses. However, these have limited water storage
capacity as they are not particularly porous. The rocks of the Midlothian Coalfield on the
eastern side of the city were never sourced because of the number of mine workings in the area.
12.48 The unconsolidated sands and gravels that underlie the small flood plains of the River Almond,
Water of Leith and Braid Burn are the fourth aquifer type. Since these are close to rivers under
low-lying ground, the water table is normally close to ground level and almost at the same level
as the river. However, groundwater in these aquifers is vulnerable to pollution at the surface.
Radioactivity
12.49 On average, natural sources account for 82% of the annual radiation dose received by Scottish
residents. These include cosmic rays, gamma rays and radon, with radon alone contributing 43%
of the total. Radon is a radioactive gas emitted from very small amounts of uranium which are
naturally present in materials such as rocks, soils, bricks and concrete. As it decays it emits
short-life products that tend to accumulate within buildings, potentially exposing occupants to a
higher risk of lung cancer. Normally, concentrations do not present a significant risk.
However, where they exceed 200 Bequerels per cubic metre of air the Health Protection Agency
(National Radiological Protection Board prior to 2005) recommends that relatively simple and
inexpensive measures should be taken to reduce them below this level.
12.50 Radon emissions are spatially variable, being associated with particular geological formations –
especially granite, limestone and metalliferous vein outcrops. Parts of the country where more
than 1% of homes are considered to be above the Radon Action Level of 200 Bq/m3 are classified
as Radon Affected Areas. Within Scotland this designation only applies to parts of
Aberdeenshire and the Helmsdale / Brora area in east Sutherland. Although Edinburgh has
some formations with low to moderate radon emission potential (e.g. limestones at Gilmerton and
Burdiehouse), there is no evidence of any significant risk. Some parts of the Pentland Hills may
have a relatively high radon potential, but these tend not to be inhabited. As Table 2 shows,
average radon concentrations in Edinburgh are well below the Action Level.
Table 2 : Radon measurements in dwellings by postcode area, Scotland, 1997
Postcode area
No. of
results
Average
radon level
(Bq / m3)
Highest
recorded
level
(Bq / m3)
Number
above
Action
Level
(*1)
1,123
74
2,200
73
Aberdeen
2,649
68
1,600
148
Galashiels
113
38
290
1
Perth
229
36
310
4
Dundee
104
31
180
0
Dumfries
283
31
150
0
Inverness
392
26
360
0
Edinburgh
92
25
100
0
Lerwick, Shetland
96
23
180
0
Falkirk
81
23
130
0
Motherwell
56
22
75
0
Kirkcaldy
95
17
61
0
Kilmarnock
98
17
58
0
Glasgow
93
15
58
0
222
13
88
0
Kirkwall
Paisley
source : Scottish Environment Statistics 1998
(*1) n.b. Kirkwall postcode area includes part of mainland
Seismic activity
12.51 Earth movements in the Edinburgh area have been localised, low magnitude, and almost
exclusively associated with former mining activity in the north Midlothian coalfield. Only the
easternmost parts of the city have been affected (Map 3). All events have registered less than 3
on the Richter scale. Being a logarithmic scale this is a very low intensity, with few noticeable
effects other than in the immediate vicinity.
12.52 With increasing time since the cessation of mining activity, collapses are tending to occur with
diminishing frequency : 35 movements were recorded by the British Geological Survey in the
coalfield area in the 1970s, falling to 31 in the 1980s and 9 in the 1990s. In fact the last recorded
sign of activity dates back to 1997.
Map 3 : Seismic activity in Central Scotland
source : British Geological Survey
Geology and the Environment
Biodiversity
12.53 The diverse topography of the Edinburgh area contains an unusually large number of rock faces
for an urban area. This reflects the City’s unique geological history, and in particular the
landforms associated with the Arthur’s Seat volcano, including Castle Rock, Calton Hill and
Arthur’s Seat itself. Although the most significant rock faces lie inland, a number of smaller
coastal cliffs also fall within the city boundary. Steep slopes and screes are also present, often
below cliff faces, most notably in Holyrood Park and at Dalmahoy and Hailes.
12.54 Rock faces contain many varied habitats, their diversity arising from variations in slope, aspect,
soil composition and microclimate. The presence or absence of disturbance is a key factor.
The resulting flora and fauna, though few in number, are often rich in diversity.
12.55 Most of the important sites in the city fall within Sites of Special Scientific Interest (SSSI’s)
shown in the Table 3 below:
Table 3 : Sites of Special Scientific Interest (SSSIs) in Edinburgh – with details of
geological interest
Name
Interest
Agassiz Rock
Quaternary. Striated rock surface. Associated
with the early development of glacial theory in
Scotland
Arthur’s Seat Volcano
Carboniferous / Permian igneous strata
Duddingston Loch
Carboniferous / Permian igneous strata
Firth of Forth (part of)
Biodiversity and geodiversity
Inchmickery Islands (Inchmickery and
Cows & Calves)
Rocky offshore islands of importance as a breeding
ground for four species of tern – common, arctic,
sandwich and roseate
Wester Craiglockhart Hill
Lowland grassland habitat
source : Scottish Natural Heritage
12.56 In addition there are 13 Local Geodiversity sites covering a range of interest. These include
former Regionally Important Geological and Geomorphological Sites (RIGS) as shown in Table
3 below.
Table 3 : Local geodiversity sites in Edinburgh, with details of geological interest
Name
Interest
Balm Well
Well seeping natural oil
Calton Hill
Comprises a sequence of lavas and interbedded
tuffs in repeated episodes. Crag-and-tail formation.
Craigleith
Gullane formation (Lower Carboniferous
Strathclyde group); sediments including river delta,
lacustrine sandstones, siltstones, mudstones
(including oil shales)
Craigmillar
Relationship between the landscape and the
underlying stratified rocks, which belong to the
Upper Old Red Sandstone or Inverclyde group of
the Lower Carboniferous.
Corstorphine Hill
Illustrates a combination of geomorphological
landforms and geological outcrops
Dreghorn Link
Cutting exposing about 80m of Upper Old Red
Sandstone sandstone and shales
Ellen’s Glen
Exposure of strata
Fairmilehead Park
Location where large glacial erratics formerly
exposed in sandpit
Hermitage of Braid
Crag-and-tail. Lower Devonian lava flow.
Joppa Shore
Carboniferous strata and sedimentary rock
Ravelston Woods
Good example of sedimentary processes of the
lower Carboniferous
Stones of Scotland
Examples of the varied geology of Scotland
Torphin Quarry
A disused quarry showing three thick basalt lava
flows, intervening tuff and barite veins
source : City of Edinburgh Council
12.57 The following Edinburgh biodiversity Action Plan species can be found in association with rock
faces and screes: Animals: Aelurillus v-insignatus (jumping spider), Ceciliodes acicula (blind white snail), Tetramorium caespitum (ant), Capperia britanniodactyla (plume moth), Glyphiptererix Minorella (micromoth),
Plants: spring sandwort, rock whitebeam, rock-rose, maiden pink, sticky catchfly, sieve- tooth
moss
Regionally Important Geological Sites (RIGS)
12.58 There are now 13 RIGS or ‘Regionally Important Geological and Geomorphological Sites’ in
Edinburgh. These are sites which have been identified by locally developed criteria, and are
currently the most important places for geology, geomorphology and soils outside statutorily
protected nature reserves and Sites of Special Scientific Interest (SSSI). The designation of
RIGS is one way of recognising and protecting important Earth science and landscape features
for future generations to enjoy. The following RIGS sites are located in Edinburgh :
•
•
•
•
•
•
•
•
•
•
•
•
Torphin Quarry (1994)
Dreghorn Link (1994)
Craigleith (1999)
Craigmillar (1999)
Hermitage of Braid (2000)
Corstorphine Hill (2000)
Joppa shore (2000)
Calton Hill (2005)
Stones of Scotland (2005)
Ravelston Woods (2005)
Ellen’s Glen (2005)
Balm Well (2005)
•
Fairmile Park – Comiston Sand Pit (2005)
Historical Links
James Hutton
12.59 Many of the early ideas and discoveries in geology were made in the Edinburgh area by James
Hutton (1726-1797), a leading member of the Scottish Enlightenment. In 1788 he published
‘Theory of the Earth’ widely regarded as the foundation of modern geology.
12.60 Hutton used a number of localities to demonstrate his theories including ‘Hutton’s Section’ at the
south end of Salisbury Crags. Here he demonstrated that the crystalline rocks of the Crags were
formed by the intrusion and cooling of hot molten rock and not, as was the view at that time, from
the cold precipitation from salts of the sea. Nearby is ‘Hutton’s Rock’ which he is reputed to
have asked the quarrymen to save as it contained a fine example of an iron ore vein. A
memorial garden marks the site of James Huttton’s Edinburgh home on St John’s Hill in the
Pleasance above Holyrood Road.
Agassiz
12.61 Another benchmark in geological understanding occurred in 1840 when the Swiss geologist,
Louis Agassiz was able to confirm for the first time that Scotland had once been covered by ice.
Striae or ice scratches on what is called Agassiz Rock on Blackford Hill were among evidence he
cited for glaciation.
APPENDIX : Quarries and former quarries identified on large scale OS maps of Edinburgh
Quarries < 0.01 hectares
Quarry
Barnton Pk.
Craigiemill
Mortonhall
Clove
Location
Grid Ref.
Area
(ha.)
Status
Balerno
314555 666830
0.09
Disused
Balerno
318604 664349
0.42
Disused
Barnton
319726 675937
0.34
Disused
Braid Hills
326083 669675
0.16
Disused
Cramond
318217 676318
0.57
Disused
Cramond
318500 676476
0.14
Disused
Dalmahoy
313371 666906
0.14
Disused
Harlaw Res.
318792 665205
0.29
Disused
Listonshiels
312862 661371
0.40
Disused
Listonshiels
312882 661189
0.12
Disused
Listonshiels
313090 661272
0.19
Disused
Listonshiels
313131 660963
0.11
Disused
Mortonhall
324747 669214
0.67
Disused
Newbridge
312817 672204
0.35
Disused
Ratho / Newbridge
312666 671164
0.44
Disused
S. Queensferry
315388 675825
0.86
Disused
Swanston
324583 667231
0.09
Disused
History / use
Quarries 0.01 to 5.0 hectares
Quarry
Location
Grid Ref.
Area
(ha.)
Status
Barnton
Barnton
320190 674991
1.86
Disused
History / use
Bonaly
319999 667583
2.35
Disused
Torphin
Bonaly
320252 667745
2.40
Disused
former whinstone
quarry
Braehead
Cammo
317424 673776
3.28
Disused
now landfill &
recycling site
Lennie
Cammo
316852 674092
2.69
Disused
Corstorphine Hill
320304 674800
2.30
Disused
Craigmillar
328580 670998
3.11
Disused
Humbie
Kirkliston
310929 675692
1.21
Disused
Niddrie
Bing
Niddrie
330657 671420
3.87
Disused
Ratho
Ratho
312831 670962
1.23
Disused
Ratho
312529 670033
1.41
Disused
Location
Grid Ref.
Area
(ha.)
Status
Blackford
326039 670284
6.45
Disused
Craigleith
1.5km NW of
city centre
322571 674671
9.84
Disused
Craigiehill
S. Queensferry
315500 676150
5.65
Disused
currently used as
national climbing
centre
Quarries 5.01 to 10 hectares
Quarry
History / use
former sandstone
quarry; now retail
park
Quarries >10 hectares
Quarry
Location
Grid Ref.
Area
(ha.)
Status
History / use
Ravelrig
Balerno
314611 666985
34.01
Operational
Bonnington
Mains
Bonnington /
Ratho
312533 670034
14.08
Operational
active hard rock
quarry
Kaimes
Kirknewton
313112 666466
19.77
Disused
formerly landfil
Craigpark
Ratho
312809 670514
32.94
Disused
1995 – permission
refused for landfill
2005 – premission
granted for housing
and public amenity
Hillwood
Ratho Station /
Newbridge
312933 671699
48.00
not in
production