OR/14/063 Site assessment - ELC 16: Cockenzie and Port Seton
|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_16: Cockenzie and Port Seton|
| Location and Summary Description:|
Cockenzie and Port Seton are located approximately 9 kilometres east of Edinburgh. The 1.7 kilometre long site displays sedimentary strata from of the Carboniferous age Upper Limestone, Passage and Lower Coal Measures formations, which are locally intruded by dykes. The Crossgatehall Fault trends south-west to north-east through the site. This site is the only known natural exposure of the Lower Coal Measures Formation in East Lothian.
| National Grid Reference:
Mid-point: 340377, 675935
| Site type:
|Site ownership: Crown Estates||Current use: Open shoreline|
|Field surveyors: Sarah Arkley and Eileen Callaghan||Current geological designations: Firth of Forth SSSI|
|Date visited: 14th May and 28th May 2014||Other designations: Firth of Forth SPA|
The villages of Cockenzie and Port Seton have a long and rich history; their harbours are used for fishing and in the past for the export of local coal. The coal that was mined within the area was used in the process of making salt and also to power the local power station. Cockenzie Power Station (ELC_16 P1) to the west of this site was opened in 1968 and was a major employer in the area but was decommissioned in 2013.
The older Passage Formation (exposed on either side and within the western wall of Port Seton Harbour due to folding) is part of the Clackmannan Group. The Passage Formation comprises a cyclic sequence of sandstone, mudstone, seatearths and siltstone with ironstone and limestone bands. The sedimentary rocks display typical sedimentary structures, including ripples and cross-bedding in sandstone, ironstone nodules within mudstones, and pebbly beds within sandstones, all indicative of formation in terrestrial fluvial environments. In places the sandstone is interbedded with thin mudstone and contains seat clays and palaeosols. Dessication cracks visible in the surfaces of some sandstone beds indicate periodic drying out of fluvial sediments during deposition. Fossilised trace fossils and marine shells are found within the sandstone, mudstone and limestone beds. Soft sediment deformation is also seen within the sandstone beds indicative of flows of sand during or soon after deposition. (ELC_16 P3).
Sedimentary rocks of the Upper Limestone Formation are exposed beneath the Passage Formation to the west and eastern margins of the site. The Upper Limestone Formation is composed of cyclic sequences of sandstones, siltstones, mudstones and thin limestones with seatearths, indicative of an alternating marine and deltaic environment (ELC_16 P4). The formation is exposed at Cockenzie Harbour where the strata comprise white to reddish, medium to coarse grained sandstone with cross and trough bedding (ELC_16 P5). Soft sediment deformation structures are well exposed and quartz pebbles are seen within the beds, possibly deposited quickly in a wet environment.
The Upper Limestone Formation exposed in the eastern part of the site comprises cyclic sequences of sandstone, which is occasionally pebbly, mudstone with ironstone nodules, siltstone, and prominent limestone with seatearths. Trace fossils and ripple structures are also seen in some exposures (ELC_16 6). The Calmy Limestone and the Orchard Limestone are exposed within the Upper Limestone sequence in the east of the site. The Calmy Limestone is exposed at low tide and is difficult to identify. It is approximately 40 cm thick and is compact, fine-grained, grey/blue with crinoid debris (ELC_16 P7). The Orchard Beds are seen on the shore and towards the wall at West Links; the beds are separated by beds of sandstone, mudstone and siltstone. Two distinctive beds are seen; the lower bed is grey and contains numerous fossils including brachiopods, corals and crinoids (ELC_16 P8). The upper bed appears to contain more crinoid debris than the lower bed with fewer brachiopods and no corals seen.
Quaternary Deposits and Landforms
Access and Additional Information
|Stratigraphy and Rock Types|
|Age: Westphalian, Carboniferous||Formation: Lower Coal Measures Formation|
|Rock type: Sandstone, siltstone, mudstone with seatearths and coals|
|Age: Westphalian, Carboniferous||Formation: Passage Formation|
|Rock type: Sandstone, mudstone, siltstone and seatearths|
|Age: Namurian, Carboniferous||Formation: Upper Limestone Formation|
|Rock type: Sandstone, siltstone, mudstone, limestone and seatearths|
|Age: Carboniferous||Formation: Central Scotland Late Carboniferous Tholeitic Dyke Swarm|
|Rock type: Quartz-Microgabbro|
|Assessment of Site: Access and Safety|
|Road access and parking||There is also parking within the town with access onto the shore.|
|Safety of access||Easy access to the shore but all visitors should be aware of the tide times when planning a visit, as the majority of the exposures are only visible at low tide and when exposed can be covered in seaweed.|
|Safety of exposure||The rocky exposures have an uneven surface and are often slippery with seaweed. Stout footwear is recommended. The site is exposed to the open sea and the weather forecast should be checked before visits.|
|Access||Access along the foreshore/beach, the John Muir Way follows the southern edge of the site.|
|Current condition||The rocks can be covered in barnacles and seaweed. The exposures at the landward edge of Cockenzie Harbour and at West Links are clear of vegetation.|
|Current conflicting activities||None.|
|Restricting conditions||Tide: many of the geological exposures are located in the intertidal range and therefore covered at high tide.|
|Nature of exposure||Intertidal and beach exposures.|
|Assessment of Site: Culture, Heritage & Economic Value|
|Historic, archaeological & literary associations|| The sea has played an important part in the history of both Cockenzie and Port Seton, Cockenzie has had a fishing harbour since the 16th century and the building of fishing vessels and yachts continued up to the 1990’s. Both Cockenzie and Port Seton harbours were also used in the export of local coal and the locally mined coal was used in the extraction process of removing salt from seawater.
Historic houses within or near Port Seton are: Seton Castle, privately owned, built on the site of 17th Century Seton Palace and also Seton Collegiate Church, 15th Century and managed by Historic Scotland.
|History of Earth Sciences||John Muir Way passes along the southern edge of the site.|
|Economic geology||Both Cockenzie and Port Seton harbours are still used in the fishing industry and local fish merchants and curers can be found in the town. Cockenzie Power Station was opened in 1968 and brought significant prosperity to the area but the power station was decommissioned in 2013. Tourism also adds to the towns in the form of Seton Sands Caravan Park which is located just outside Port Seton.|
|Assessment of Site: GeoScientific Merit|
|Igneous/Mineral/Metamorphic Geology||Local||Moderately Good|
|Site Geoscientific Value|
This site displays a sequence of the Upper Carboniferous; the Upper Limestone Formation, the Passage Formation and the Lower Coal Measures Formation. Rare exposures of the Calmy and Orchard Beds Limestones are also found at this site.
|Assessment of Site: Current site usage|
|Community||The easy access to the shore and the shore walkway is used regularly by locals. The John Muir Way passes through Cockenzie and Port Seton which attracts visitors from further afield.|
|Education||The site displays a variety of features suitable for amateur geologists to study depositional sedimentary environments. The limestone strata exposed in this site offers the study of fossils. The Port Seton-Spittal dyke is well exposed and provides some evidence of contact with the sedimentary rocks.|
|Assessment of Site: Fragility and potential use of the site|
|Potential use||There are various places where on-site interpretation could be located also a geo-trail extending to Prestonpans could be considered. The area could be studied by, school and higher education.|
| This site contains a good variety of geological features especially associated with sedimentary strata. It exposes a sequence of the Upper Carboniferous including the Lower Coal Measures Formation, the only coastal exposure in East Lothian; also the Port Seton-Spittal dyke is seen intruding into this sequence. The sedimentary structures and the fossils seen in the Calmy and Orchard limestones allow interpretation of the depositional environments of each formation. The fossils at this site are one of the best exposures on the East Lothian coast.
The coastline is attractive and has easy access. There are numerous possibilities for adding geological interpretation to this site, especially along the John Muir Way.