This repository contains a GeoPackage of a set of polygons suitable for constructing a 7-continent layer from terrestrial polygons.
For example, Natural Earth, OpenStreetMap or GADM polygons can be intersected with these polygons to derive the continents:
They are intended for use indexing occurrences in GBIF.org.
Refer to Boundaries between the continents of Earth for a general background, to the World Geographical Scheme for Recording Plant Distributions (WGSRPD) to justify some decisions on where to group islands, and to the polygons themselves.
The boundaries are drawn carefully across land, but roughly across the sea. These polygons are not intended to represent accurate maritime boundaries! Continents are landmasses, so the marine boundaries are not important, except as they include or exclude islands from the continents.
The boundaries are as follows:
Clockwise from Egypt, the terrestrial border with Asia follows the Isthmus of Suez, using the western channels of the Suez Canal from OSM.
The marine boundary roughly follows the maritime boundaries through the Gulf of Suez, with the Yemeni island of Socotra in Africa.
The Seychelles, Mauritius and Comoros are grouped with Africa.
The Scattered Islands in the Indian Ocean between the African mainland and Madagascar are grouped with Africa, the others in Antarctica.
The Prince Edward Islands of South Africa are assigned to Antarctica.
Tristan da Cunha, Saint Helena and Ascension islands are grouped with Africa.
Malta, the Italian island of Lampedusa and the Spanish islet of Alboran Island are grouped with Europe.
Continuing from Egypt at the Suez Canal, clockwise.
Cyprus is part of Asia, along with most of Turkey and the western Aegean Islands of Greece.
The border continues through the Black Sea and follows the crest line of the Caucasus and crosses the Caspian Sea to the mouth of the Ural River. This part of the border is taken from a dataset produced by Sasha Trubetskoy.
The border follows the Ural River (from OpenStreetMap) as far as the source at Bashkortostan–https://en.wikipedia.org/wiki/Chelyabinsk_Oblast[Chelyabinsk] Oblasts' borders.
Trubetskoy’s line then continues, following the Ural Mountains to the Kara Sea.
The Russia/USA border follows the national boundaries, including the separation of the Diomede Islands, and the Aleutian Islands (including the Near Islands) being North American.
The Japanese island of Minami-Tori-shima is grouped with Oceania, but the Bonin Islands, Volcano Islands, Nishinoshima and Okinotorishima with Asia.
For the boundary between Asia and Oceania in the Malay Archipelago, the Lydekker Line is used.
Christmas Island and the Cocos (Keeling) Islands remain in Asia, even though they are on the Australian plate.
The Azores are grouped with Europe.
South America includes the nearby islands of Trinidad and Tobago, Galápagos Islands, Malpelo Island, Desventuradas Islands and the Juan Fernández Islands.
The boundary with North America uses the northern part of the Colombia/Panama border from OpenStreetMap.
The islands of the Caribbean, including parts of Colombia and Venezuala and Clipperton Island are grouped with North America.
This includes Australia and most Pacific islands, including Hawaii and Easter Island.
The Heard and McDonald Islands are grouped with Antarctica.
So are the South Georgia and South Sandwich Islands and several of the French southern territories.
The database/import.sh script of GBIF’s Geocode project shows importing these polygons and intersecting them with GADM level 0 polygons within PostGIS.
They are intended for using in GBIF’s data processing and interpretation procedures.
Since the terrestrial boundaries follow Open Street Map polygons/lines, this dataset is licensed as a derivative of Open Street Map using the Open Data Commons Open Database License (ODbL).