[Rockhounds] The Cornish hut that gave rise to sea level benchmark

[Kreigh Tomaszewski]

*It's not much to look at - an anonymous red-and-white concrete hut that
has that familiar battered seaside look.*

But the building, on the end of South Pier in Cornwall's Newlyn Harbour, is
celebrating an important anniversary.

It was measurements made in the hut, and completed on 30 April 1921, that
established mean sea level.

And it's this surface, known as Ordnance Datum Newlyn (ODN), that became
the reference against which all other elevations were compared.

Every hill, mountain and building in Britain could be described as being so
many feet above the Cornish benchmark.

"Without that datum point, without that 'height zero' level that everyone
agrees to use, nothing we do would fit," said Mark Greaves, from Ordnance
Survey (OS) <https://www.ordnancesurvey.co.uk/>, the UK's national mapping
agency.


https://www.bbc.com/news/science-environment-56935097