According to Wikipedia:
A stack or sea stack is a geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coast, formed by wave erosion.
Sea stacks are commonly small islands, often with cliff faces and with a surface of bare rock. Wikimedia Commons has a good collection of exemplary images.
Mapping a sea stack in OSM is a challenge because it would (often) require the combination of natural=coastline + natural=cliff + natural=bare_rock + place=islet at the outline of the stack. Sometimes, even natural=arch is appropriate for the same outline. Of course, natural=coastline is special and can’t have additional semicolon separated tag values.
I have seen mappers use several different approaches to combine these tags.
The OSM Wiki guidance for natural=coastline is to use a separate multipolygon relation for an additional natural=* value. But I have also seen mappers stack congruent ways, glued together, each with a separate set of tags. Omitting either cliff or bare_rock is another common approach.
In theory, natural=cliff;bare_rock (or bare_rock;cliff) would be possible to combine the tags, but this is apparently never used in practice.
Is there a good way to combine these tags for this type of feature?
6 posts - 2 participants
Ce sujet de discussion accompagne la publication sur https://community.openstreetmap.org/t/properly-mapping-sea-stacks/105254