This page is devoted to underground features
that are artificial.
The Sidmouth Tunnel
This curious underground feature lies about
250 metres east of the river mouth at Sidmouth. Driven in
the early 19th century to carry stone from quarries further
along the coast it was abandoned when the train that was supposed
to use it was found to be too big. The tunnel contains deep
water in sections and is home to lesser horseshoe bats. About
200 metres remain, and when the cliff line erodes back to
the tunnel, which runs parallel to the cliff, there will be
a very spectacular cliff fall! Although the rock is relatively
unstable red marl it contains enough calcium carbonate for
stalagmite formations to have developed making the walls quite
colourful in places.
Crimson Hill Canal Tunnel
This 1800 yard long tunnel was excavated in
the mid 19th century for the Chard to Taunton Canal which
in the event only operated for 15 or so years. There were
three tunnels. An estimated 1300 yards of tunnel is still
accessible although one end is in a private garden. A footpath
passes the northern end and there is an interpretation board
nearby which gives more information about the tunnel. Apart
from containing some colourful calcite formations formed from
leached mortar the tunnel provides a haven for wildlife in
the winter including roosting horsehoe bats, frogs, toads
and newts. Visitors to the tunnel should ask permission before
entering it. The pipework near the entrance is connected to
a pump for a farm water supply and activity in the tunnel
blocks the water filter. A geocache was placed inside the
tunnel a few years ago and the number of visitors increased
dramatically which did not please the landowner who had to
keep clearing the filter!
The Northern Entrance |
Just inside |
View up the tunnel |
One of the presumed drainage holes in the wall |
Stalactite formations |
Near the collapse |
Stalagmite pillar |
Lesser horseshoe bat visible on top left |
The point at which the tunnel widens |
The main collapse |
Calcite in the Lias |
Stalactites |
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Upstream of the collapse |
By a wall collapse |
Stalagmite flow behind the tunnel wall |
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800 metres in the tunnel reaches an earth choke |
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At the choked terminus |
The Southern entrance - in a private garden and reexcavated
by the owner |
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Peter Rose, Master Mariner, low water conditions |
Near the entrance in high water - January 2nd 2010 |
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Ken Passant examines one of the niches along the walls |
Helictites |
Mini grotto in an alcove |
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Ken in low water manoeuvres amongst the straws |
Loking back towards the entrance - light can be seen
from nearly half a mile in |
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Deep water in winter with Martin Grass admiring a particularly
large and colourful formation |
Water cascading from the roof in the distance |
Delicate boat navigation required! |
The water is beautifully clear |
Scoff at the mud choke 600 yards or so in |
Lillesdon Canal Tunnel
This 400 yard long tunnel is also part of the
defunct Chard to Taunton Canal and lies not far to the north
of Crimson Hill. It is still open at both ends although the
northern is partly obstructed by pumping equipment which is
in use at the time of writing. There is about a metre or so
of water in the tunnel and it is navigable by dinghy for most
of its length. 100 metres or so from the southern end is a
turning area and the tunnel is partially filled with silt
making the final few metres very tricky to negotiate. There
are no collapses and the tunnel is well preserved with numerous
stalactite formations along the walls.
Penrecca Slate Mine
Cornish Mines
Wheal Friendship
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