[HN Gopher] The Curious Gems of the River Thames
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The Curious Gems of the River Thames
Author : alt227
Score : 43 points
Date : 2025-01-13 15:13 UTC (7 hours ago)
(HTM) web link (www.atlasobscura.com)
(TXT) w3m dump (www.atlasobscura.com)
| tocs3 wrote:
| I would like to see some of the faceted garnets found. The ones
| in the pictures all look natural to me.
| TSiege wrote:
| the cover photo is faceted. several in the photos are
| dghughes wrote:
| The second last photo labelled "Thames garnets tend to appear
| in specific spots along the riverbank, but those locations are
| carefully guarded among mudlarks. Courtesy Jason Sandy" you can
| see a big one. It has what looks to be a five-sided facet
| that's reflecting light.
| adrian_b wrote:
| The natural garnet crystals have frequently the form of
| rhombic dodecahedra (i.e. with 12 rhombic faces disposed in
| the directions of the 12 edges of a cube).
|
| Such crystals may be eroded to more rounded forms, but some
| of the original plane faces may remain more or less intact.
|
| It is hard to be sure from the image, but the garnet below
| the title may be not artificial, but just an eroded natural
| garnet that originally was a rhombic dodecahedron.
|
| The same can be true for other faceted garnets. Only a more
| thorough examination can distinguish natural crystals from
| those that have been polished, so they have plane faces with
| other orientations than the faces of the natural garnet
| crystals.
| pavel_lishin wrote:
| > _Only a few people are legally allowed to hunt for Thames
| garnets--or even remove them if they find them by chance.
| Mudlarks are among the few who are legally permitted to remove
| items from the riverbanks. To be a mudlark, you need a license,
| and in recent years, the British government suspended the issuing
| of new licenses for several years following a boom in
| applications during the pandemic lockdowns, leaving the already
| tight-knit mudlark community in a holding pattern._
|
| Well, that's something new I learned today. I wonder why they
| have to be licensed?
| notavalleyman wrote:
| Here's a licence issuing authority's faq section.
|
| https://pla.co.uk/thames-foreshore-permits
|
| >Why do I need consent?
|
| > All the foreshore in the UK has an owner. Metal detecting,
| searching or digging is not a public right and as such it needs
| the permission of the landowner. The PLA and the Crown Estate
| are the largest landowners of Thames foreshore and jointly
| issue a permit, which is administered by the PLA, allowing all
| searching, metal detecting, 'beachcombing', scraping and
| digging.
|
| Another section reads,
|
| > The foreshore of the river Thames is a sensitive environment
| and London's longest archaeological site, with finds dating
| back to 10,000 BCE. It is also the border to the UK's biggest
| port and busiest inland waterway and must be protected and
| respected by all that use it.
|
| > The Thames foreshore is a potentially hazardous environment
| which must be respected; it contains many dangers that may not
| always be immediately apparent. The Thames can rise and fall by
| over seven metres twice a day as the tide comes in and out. The
| current is fast and the water is cold.
| pavel_lishin wrote:
| SEVEN METERS!? Wow!
| alt227 wrote:
| The UK has some really big tides.
|
| See the river Severn, whos estuary tidal range is 15
| metres, and the second highest in the world.
|
| https://en.wikipedia.org/wiki/Severn_Estuary
| ncruces wrote:
| An image/map:
| https://en.wikipedia.org/wiki/File:M2_tidal_constituent.jpg
| wongarsu wrote:
| Basically the UK is in the way when a sizable chunk of
| the Atlantic wants to move north-west to follow the
| tides. The water squeezes into whatever openings it can
| find and creates really high tides in the process
| jedc wrote:
| I used to row in London on the Thames, and yeah, the tides
| are nuts. The river rises seven meters in the span of about
| 3-4 hours. (It takes about 7-8 hours to flow out.)
| mkl wrote:
| It's a largely artificial problem, too, with very small
| tidal effects originally.
| https://en.wikipedia.org/wiki/Embanking_of_the_tidal_Thames
|
| The original marshlands were drained gradually for
| agriculture, and the land sank as it dried. The southeast
| of the island has been sinking relative to sea level for
| natural reasons as well.
|
| From the link above:
|
| > The Embanking of the tidal Thames is the historical
| process by which the lower River Thames, at one time a
| shallow waterway, perhaps five times broader than today,
| winding through malarious marshlands, has been transformed
| by human intervention into a deep, narrow tidal canal
| flowing between solid artificial walls, and restrained by
| these at high tide.
|
| > With small beginnings in Roman Londinium, it was pursued
| more vigorously in the Middle Ages. Mostly it was achieved
| by farmers reclaiming marshland and building protective
| embankments or, in London, frontagers pushing out into the
| stream to get more riverfront property. Today, over 200
| miles of walls line the river's banks from Teddington down
| to its mouth in the North Sea; they defend a tidal flood
| plain where 1.25 million people work and live. Much of
| present-day London is recovered marshland: considerable
| parts lie below high water mark.
| trhway wrote:
| For your further amusement - tide-proof "coastline railway
| in Brighton, England, that ran through the shallow coastal
| waters" :) And electric at that!
|
| https://en.wikipedia.org/wiki/Brighton_and_Rottingdean_Seas
| h...
|
| " The single car used on the railway was a 45 by 22 ft
| (13.7 by 6.7 m) pier-like building which stood on four 23
| ft (7.0 m)-long legs."
| RajT88 wrote:
| >London's longest archaeological site
|
| The English have a bit of a history when it comes to looting
| historical artifacts. They would like to exercise some
| control over when they are found, I imagine.
| multjoy wrote:
| The Elgin marbles are named for the _Scottish_ noble who
| purloined them. It as much a British thing as it is an
| English one.
| myself248 wrote:
| In my mind, "gems" is pronounced "games", just to mess with
| foreigners.
| Jun8 wrote:
| Not these gems but my son and I hunted for and found a couple of
| 19th century single use pipes and part of a brick with a cool
| logo a couple of years ago. Go to the Tower Bridge, there are
| stairs to go to the shore right next to it. Good hunting!
| pbalau wrote:
| Before you do that, you need to be very careful about two
| things:
|
| 1. Tide state, witch I did
|
| 2. Dog poo, which I didn't and there is a pub I won't ever go
| back to, as I discovered the poo issue quite late.
| mkl wrote:
| The article says you need a licence, or is that location
| different?
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(page generated 2025-01-13 23:01 UTC)