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Industrial Archeology and clay mines
Does anyone know much about clay mining?
On Brownsea Island in Poole Harbour, we're currently clearing rhododendron from
an area that used to be dug for clay. The clay was pretty low grade, used for
drainage pipes and the like, but we've uncovered a lot of ventilation shafts.
They look like giant well heads, about ten feet in diameter and are made of
brick. We've found six or seven now - and the top of all of them is very close
to sea level. The rim is maybe five or six feet above the sea.
If they were ventilation for a mine, then the mine would have been entirely
below sea level. I find it hard to believe that a mine for clay would have been
econimic, especially as the surrounding 'rock' seems to be a loose sand.
Shoring it up would have been difficult and dangerous.
A lot of clay was dug from the surface; an old map of the island shows a pool
called 'clay pit' which we rediscovered around three years ago (it was
completely hidden by rhododendron and eventually turned out to be a hundred
metres or so in length).
Why mine underground? Perhaps digging the pit deeper and deeper risked
subsidence or too much incursion of sea water. The pit is effectively at sea
level with a barrier of only a few feet between it and the sea. (It may have
been higher in earlier times as there are some steep slopes close to the area
that could have been cut back by digging)
On Brownsea Island in Poole Harbour, we're currently clearing rhododendron from
an area that used to be dug for clay. The clay was pretty low grade, used for
drainage pipes and the like, but we've uncovered a lot of ventilation shafts.
They look like giant well heads, about ten feet in diameter and are made of
brick. We've found six or seven now - and the top of all of them is very close
to sea level. The rim is maybe five or six feet above the sea.
If they were ventilation for a mine, then the mine would have been entirely
below sea level. I find it hard to believe that a mine for clay would have been
econimic, especially as the surrounding 'rock' seems to be a loose sand.
Shoring it up would have been difficult and dangerous.
A lot of clay was dug from the surface; an old map of the island shows a pool
called 'clay pit' which we rediscovered around three years ago (it was
completely hidden by rhododendron and eventually turned out to be a hundred
metres or so in length).
Why mine underground? Perhaps digging the pit deeper and deeper risked
subsidence or too much incursion of sea water. The pit is effectively at sea
level with a barrier of only a few feet between it and the sea. (It may have
been higher in earlier times as there are some steep slopes close to the area
that could have been cut back by digging)
no subject
It has to be over 70 years old simply because of the age of the rhododendron.
There was a small tramway here at some point. The only trace left now is a short ridge all of three feet high where it ran along the shore close by all these shafts.
The island was used as a decoy for Poole during the war. The resulting bomb craters are now used to store water in.
Gun emplacments would logically be at the end of the island facing the harbour mouth (nearly a mile away from the clay pits). There have been guns there at some points in the island's history. There's some old canon down that end.
The red squirrels are doing well. As the rhodendron is reduced, the amount of pine increases. More pine = more squirrels.