and the nearby Wadbury valley display some fascinating geology
and industrial archaeology. The village is located on the northern
flank of the Mendip Hills, where the Triassic and Jurassic rocks
lap onto the older, highly folded and contorted Carboniferous Limestone
and Coal Measures.
The Carboniferous Limestone forms the extensively quarried higher
ground south of the village, with the softer coal-bearing mudstones
outcropping to the west. North of Mells, the Jurassic Inferior Oolite
and the overlying Great Oolite Group overlie the Carboniferous strata
and form the escarpment of Newbury Hill and Mells Down. From Mells,
the most spectacular geology and industrial archaeology can be seen
on a walk down the Wadbury valley.
Aerial view of the Wadbury valley (click to enlarge view).
Here the Mells River flows through a narrow valley excavated in the
harder, steeply dipping Oxwich Head Limestone.
The Wadbury valley contains some fascinating industrial archaeology.
Three of the six Fussell's iron works occur here, which in their
heyday in the 19th century produced some of the finest edged tools
in the country. The Upper Works were located on the bend of the river
at the head of the Wadbury valley. A few hundred metres down stream
are the remains of the Lower Works, while the remains of the Great
Elm Edge Tool Works lie about 150 m downstream of the confluence
with Fordbury Bottom.
and stream sinks
Near the upper end of the Wadbury valley is the outfall from Whatley
Quarry. Groundwater from the quarry is pumped here to help maintain
river flow and to help recharge the underground aquifers. Just downstream
is the Mells River Sink, a cleft that acts either as a sink or a
spring depending on the relative levels of the river and the water
The rift in the hill above the sink is a cave developed along the
line of a 'Neptunian dyke', a fissure in the Carboniferous Clifton
Down Limestone infilled with younger Jurassic Lower Lias Downside
The narrow densely wooded valley and the old iron works support a
rich diversity of mosses, liverworts and ferns. The hart's-tongue
fern is particularly common along the river banks. The old iron works
are also important bat roosts.
|| Further down the valley
near Great Elm is the prominent entrance of Spleenwort Shelter, a
short cave developed in the Carboniferous Clifton Down Limestone.
Cross-section and plan of Mells River sink (click to enlarge).
Tedbury Camp Quarry provides one of the best and most accessible
exposures of the unconformity between the steeply dipping, massively
bedded, grey Carboniferous Clifton Down Limestone and the overlying
horizontally bedded, yellow Jurassic Inferior Oolite. Although the
quarry is disused, it is still owned by Hanson Aggregates who allow
access to the site. A large flat area of rock has been exposed where
the Inferior Oolite has been stripped in preparation for blasting.
This surface was once the sea floor in Jurassic times and is encrusted
with fossil oysters and the underlying Carboniferous Limestone has
been bored by worms and bivalves. These borings have been infilled
with Jurassic sediment.
Map of Tedbury Camp Quarry (click to enlarge). Copyright Martin
Whiteley Barrisdale Ltd.