| The Wookey
Hole catchment drains the southern side of North Hill and the northern
side of Pen Hill. At over 9.4 km in length, the longest cave on Mendip
is Swildon's Hole, a classic swallet cave system near Priddy. First
descended in 1901 it is one of the earliest systematically explored
caves in Britain. The streamway initially cascades steeply down a
large vadose canyon to Sump 1, a totally water-filled section. Beyond
it the passage gradient slackens and the streamway changes to a series
of phreatic loops. The troughs are marked by ten further sumps before
becoming impassable at a twelfth. Above lie series of abandoned passages
at several levels, representing former courses of the stream.
St Cuthbert's Swallet nearby is a similar swallet cave, 6.7 km long,
with numerous vadose canyons developed either side of a plunging
anticline uniting at depth into a single phreatic streamway.
collapse and sediment infilling has modified much of the original
system, which is well decorated with stalagmites and stalactites.
The adjacent Eastwater Cavern (2.5 km long) is a similar, but smaller
complex maze. These caves
have been traced to Wookey Hole, a 3.6 km long resurgence cave. Part of the cave is open to the
public and the cave has been the site of many pioneering cave dives.
Here, the River Axe flows through a series of phreatic loops up to
90 m deep within the Carboniferous Limestone before reaching daylight
via a series of shallower sumps developed in the overlying Triassic
Several other small relict caves, notably Hunter's Lodge Inn Swallet,
Hunter's Hole and Templeton Pot have been discovered by excavating
some of the many sinkholes in the area.