Prehistoric Britain

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Megaliths

Currently (September 2014) OSM data of UK megalithic sites is poor, with many sites unmapped. Furthermore the tagging of sites that are mapped is generally incomplete, using various and incompatible tags making it difficult for map renderers and applications to find and display. Some examples of tags currently in use;

historic=ruins

man_made=stone_circle

historic=archealogical_site site_type=dolmen or site_type=bigstone


The aim of this project is to map the extant prehistoric man-made stone structures in the United Kingdom. As such we want to;

  • Add missing megaliths to the map, using Bing aerial imagery or ground surveys.
  • Make tagging consistent
  • Make tags as complete as possible
  • Add links to external sources of information - Wikipedia etc.


I propose the following schema to standardize the mapping of prehistoric megaliths in the UK, including a set of tags which, as far possible, follows the majority of the tagging schemas already in use for megaliths in the UK and abroad.


Mapping

Megaliths should be mapped with one of;

  • a node at the centre of the site
  • a closed way marking the perimeter of the site.
  • a relation connecting a set of nodes or ways which mark structures in the site


At a minimum the following tags should be applied to all prehistoric megalithic sites;

name=*

tourism=attraction

historic=archealogical_site

historic:civilization=prehistoric

site_type=megalith


And one of;

megalith_type=dolmen For megalithic tombs, dolmens, quoits and cromlechs.

megalith_type=menhir For standing stones

megalith_type=alignment Stone alignments or rows

megalith_type=stone_circle Stone circles



If required, individual stones or structures can be mapped as closed ways and tagged;

building=yes

Optionally, the following tags can also be used for individual stones (though these tags and values seem non-standard);

historic=monument

monument=obelisk


If individual or multiple stones are mapped, then either

a) an area around them should be mapped by a closed way (this may only be approximate), with the tourism=*, name=*, historic=archealogical_site etc tags.

or

b) they should be connected with a relation, which is itself tagged with the standard set of tags.


Dating

A distinction can be made between stone age and bronze age megaliths - in the British Isles the beginning of the bronze age is often stated as somewhere between 2000 and 2300 BC. However this is not a completely objective distinction - the 'bronze age' arrived at different times in different places around the globe, and furthermore the age of many megaliths in the UK are uncertain.

However, if there is a generally accepted era for a site then the following tags could be used;


For stone age sites;

historic:period=stone-age

historic:era=neolithic


For bronze age sites;

historic:period=bronze-age


More specific dates can also be used, if they exist.

start_date=3100 BC

start_date=before 2000 BC

start_date=~1500 BC


Access

access=yes Site is on public land or land over which the public has legal right of way.

access=permissive Site is on private land but is open to the public. The owner can at some time in the future revoke permission.

access=no or access=private Site is inaccessible to the public.

fee=yes Site has an entrance fee.

opening_hours=* Site opening hours.

operator=* The company or authority that runs the site, e.g. operator=English Heritage


Condition

Britain's prehistoric megaliths exist in a variety of states; some well preserved, others have been recently restored, but many have been completely destroyed or survive only as a few scattered rocks. I would propose a tagging scheme to indicate the current condition of megaliths, something like site_condition=* or megalith_condition=*, with perhaps a descriptive or numerical value attached.

Would be worth investigating how this could be objectively quantified, or what, if any, authoritative sources exist for this information.


Links to other websites

wikipedia=* Link to the Wikipedia article for the site, if it has one.

website=* Link to the official website for the megalith, if it has one.


Cornwall

Name Type Rendering Notes
Boscawen-Un Circle Way 301802425 (XML, Potlatch2, iD, JOSM, history)
Boskednan Circle Way 240343058 (XML, Potlatch2, iD, JOSM, history)
Bosporthennis Quoit Dolmen Unmapped
Carwynnen Quoit (The Giant's Quiot) Dolmen Node 3071462066 (XML, Potlatch2, iD, JOSM, history)
Chûn Quoit Dolmen Node 1415828235 (XML, Potlatch2, iD, JOSM, history)
Craddock Moor stone circle Circle Way 266408369 (XML, Potlatch2, iD, JOSM, history)
Devil's Quoit Dolmen Node 3071485102 (XML, Potlatch2, iD, JOSM, history)
Duloe stone circle Circle Way 302807759 (XML, Potlatch2, iD, JOSM, history)
Fernacre Circle Way 60879866 (XML, Potlatch2, iD, JOSM, history)
Goodaver stone circle Circle Way 302817147 (XML, Potlatch2, iD, JOSM, history)
The Hurlers Circle Way 189091883 (XML, Potlatch2, iD, JOSM, history) Multiple unconnected ways and nodes
Lanyon Quoit Dolmen Node 600206371 (XML, Potlatch2, iD, JOSM, history)
Leaze stone circle Circle
Mên-an-Tol Circle Node 600206218 (XML, Potlatch2, iD, JOSM, history)
The Merry Maidens Circle
Nine Maidens Stone Row Alignment Way 302868054 (XML, Potlatch2, iD, JOSM, history)
Nine Stones of Altarnun Circle
The Pipers Menhir Way 302822731 (XML, Potlatch2, iD, JOSM, history)
Stannon stone circle Circle Way 118846317 (XML, Potlatch2, iD, JOSM, history)
Stripple stones Circle
Tregeseal East stone circle Circle
Trethevy Quoit Dolmen Node 2150848970 (XML, Potlatch2, iD, JOSM, history)
Trippet stones Circle Way 240342854 (XML, Potlatch2, iD, JOSM, history)
Zennor Quoit Dolmen Node 3073528646 (XML, Potlatch2, iD, JOSM, history)

Dorset

Name Type Rendering Notes
Stonehenge Circle Way 37118074 (XML, Potlatch2, iD, JOSM, history)


Devon

Name Type Rendering Notes
Kingston Russell Stone Circle Circle Way 425722873 (XML, Potlatch2, iD, JOSM, history)

Wiltshire

Name Type Rendering Notes
Stonehenge Circle Way 37118074 (XML, Potlatch2, iD, JOSM, history)


External Links

  • Overpass Turbo a rendering of the megalithic sites in Britain following the above schema