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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
Ours isn't the decoy site either (doesn't match description and is in the wrong place). However, I suspect we may end up clearing there eventually - if it's hidden under heavy growth, then the growth is probably rhododendron. We might get there in five or six years...