OR/14/063 Site assessment - ELC 19: North Berwick Law

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Whitbread, K, Ellen, R, Callaghan, E, Gordon, J E, and Arkley, S. 2014. East Lothian geodiversity audit. British Geological Survey Internal Report, OR/14/063.
ELC_19: North Berwick Law
Site Information
Location and Summary Description:

Located on the southern outskirts of North Berwick, North Berwick Law is a fine example of a crag and tail landform shaped by differential glacial erosion of a phonolitic trachyte plug. It forms a distinctive and characteristic landmark in East Lothian.

National Grid Reference:

Mid-point: 355847, 684235
West end: 355295, 684150
East end: 356397, 684386

Site type:
  • Natural landform
  • Natural view
  • Artificial quarry works
Site ownership: Part council, part private Current use: Open country, agricultural land
Field surveyors: Rachael Ellen, Eileen Callaghan, Sarah Arkley and John Gordon Current geological designations: None (Formerly designated as a geological SSSI but denotified)
Date visited: 25th April, 20th August and 4th October 2014 Other designations: SSSI for Lowland calcareous grassland
Site Map
Figure 24    North Berwick Law Location Map. The site boundary includes the crag and tail feature of North Berwick Law and related bedrock exposures, only the proximal part of the landform 'tail' to the east is included. The site boundary coincides in part with that of the lowland calcareous grassland SSSI.
Site Description
Background

The site is a prominent landmark on the southern outskirts of North Berwick (ELC_19 P1) and widely visible from across the region and parts of Edinburgh and Fife. The summit of the Law provides an excellent viewpoint to appreciate the geology and landscape of East Lothian. Historically, the trachyte was quarried on the south side of North Berwick Law for building stones of many of the dwellings within North Berwick.

Igneous Rocks
North Berwick Law, the remnants of a Carboniferous volcanic plug, is composed of a medium-grained feldspathic phonolitic trachyte. The volcanic plug was probably exposed by weathering and erosion of the original volcanic structure over millions of years during pre-glacial times. The hard volcanic plug is more resistant than the adjacent Carboniferous basaltic lavas, tuffs and sedimentary rocks through which it was intruded. A disused quarry to the south of the site provides fresh exposures of the trachyte (ELC_19 P2), whilst there are plenty of weathered and glacially smoothed exposures to examine adjacent to the many paths leading to the summit of the Law.

Quaternary Deposits and Landforms
North Berwick Law rises some 120 m above the adjacent land surface. During the course of repeated Quaternary glaciations, it has been moulded by the passage of ice sheets from a westerly direction, forming a classic 'crag and tail' landform. Differential glacial erosion has enhanced the form of the 'crag', leaving a streamlined 'tail' of rock and glacial till over 1 km long on the more protected lee side to the east (ELC_19 P1, P3). Outcrops of ice-moulded rock occur on the upper slopes of the Law (ELC_19 P4). Overdeepened depressions are present to the north and south of the Law, due to the scouring of ice diverted around the base of the crag. This is most clearly seen on the south side; the northern depression being infilled by postglacial sediment. A glacial drainage channel occurs immediately to south west of the Law.

Access and Additional Information
The Law itself is easily accessible from North Berwick.

Stratigraphy and Rock Types
Age: Carboniferous Formation: Southern Scotland Dinantian Plugs and Vents Suite
Rock type: Phonolitic trachyte
Age: Carboniferous Formation: Garleton Hills Volcanic Formation
Rock type: Basaltic tuff
Assessment of Site: Access and Safety
Aspect Description
Road access and parking North Berwick Law is probably best viewed from various locations in and around North Berwick. There is a free car park on the west side of the Law. North Berwick is accessible by train from Edinburgh and it is a short walk from the station to the Law. The town also has bus links with Dunbar, Haddington and Edinburgh. The John Muir Way passes along the west side of the Law.
Safety of access Care is required if climbing to the summit of North Berwick Law due to the steep, rough path.
Safety of exposure Care should be taken if visiting the quarry, the floor of which is becoming overgrown.
Access Access by footpath.
Current condition Access to, and visibility of, the overall landform and quarry exposures are good. However, the floor of the quarry is becoming overgrown by vegetation.
Current conflicting activities Rock climbing in the quarry may restrict access at times.
Restricting conditions Rock climbing in the quarry may restrict access at times.
Nature of exposure Disused artificial quarry works, hill with panoramic views and natural exposures.
Assessment of Site: Culture, Heritage & Economic Value
Aspect Description
Historic, archaeological & literary associations An Iron Age hill fort and hut circles are present on the Law. There are also the remains of buildings that were used as lookouts in the Napoleonic Wars and the Second World War.

North Berwick Law also formed a backdrop to sketches by JMW Turner of Tantallon Castle (see <http://www.tate.org.uk/art/artworks/turner-tantallon-castle-and-north-berwick-law-d13332>).

Aesthetic landscape Coastal landscape; hill.
History of Earth Sciences The John Muir Way passes through the site.
Economic geology Red phonolite was extracted from the former quarry on the south-west side of the Law to build many of the distinctive historic buildings of North Berwick.
Assessment of Site: GeoScientific Merit
Rarity Quality Literature/Collections Primary Interest
Lithostratigraphy
Sedimentology
Igneous/Mineral/Metamorphic Geology Regional Good
Structural Geology
Palaeontology
Geomorphology Regional Good X
Site Geoscientific Value

North Berwick Law is an Good example of a crag and tail landform associated with resistant volcanic outcrops in lowland glaciated terrain. The phonolitic trachyte rock of the Law is rare in the Midland Valley of Scotland.
The site is a good educational example of a crag and tail landform, and of a volcanic plug.

Assessment of Site: Current site usage
Community The Law is a popular local walk. It is managed as a Countryside Site by East Lothian Council.
Education The site is a good educational example of a crag and tail landform, and of a volcanic plug.
Assessment of Site: Fragility and potential use of the site
Fragility Weathering/erosion, natural overgrowth, likelihood of development.
Potential use School education, on-site interpretation linking geology and archaeology interests, link to coastal geological walks and the John Muir Way.

The site could also be incorporated into existing interpretation materials, such as those provided by the Scottish Earth Science Education Forum and Lothian and Borders RIGS Group.

Geodiversity Summary
North Berwick Law is a good example of a Carboniferous volcanic plug, and an excellent example of a crag and tail landform indicative of the lowland glaciation of East Lothian. The site is easily accessible and there is good potential for improving the interpretation and educational use of the site.
Site Photos
Photo ELC_19 P1:    North Berwick Law crag and tail viewed from the south-east. © John Gordon.
Photo ELC_19 P2:    Former quarry on the south-west side of North Berwick Law showing exposures of phonolitic trachyte. The quarry floor and faces are becoming overgrown in places. © John Gordon.
Photo ELC_19 P3:    North Berwick Law crag and tail: view looking down on the 'tail' from near the summit of the Law. © John Gordon.
Photo ELC_19 P4:    Ice-moulded bedrock near the summit of North Berwick Law. © John Gordon.