The grit stone uplands above Grassington and
Hebden were far less productive agriculturally, but what was
lacking in farming, they made up for this with the discovery of
lead ore.
There was lead working at nearby Greenhow
from Roman times and Grassington Moor has a long history of lead
mining with records dating back to the 15th Century at a time when
the monks of Fountains Abbey worked a smelt mill.
The medieval monastic estates secured their
share, but the industry really took off in the 18th and 19th
centuries when large numbers of people were employed in the mines,
smelt mills and dressing floors at Yarnbury and on Grassington
Moor.
The mineral rights here were held by the Duke
of Devonshire, and he provided the capital investment that allowed
the mines to flourish. He built a large smelt mill and provided
vital drainage systems for the deep mines.
The mines entered their most prosperous phase
between 1821 and 1861, when they produced 20,273 tons of lead,
averaging 965 tons a year and employed about 170 people. After
1861, output fell steadily as the mines became exhausted, finally
closing in 1880.
There has been no serious attempt to reopen
the mines since 1880, but barytes, fluorospar and some lead ore has
been recovered from the waste dumps. The largest of these
operations were undertaken by Grassington Lead Mines Ltd between
1916 and 1920 and the Dales Chemical Company between 1956 and
1963.
In order to complete the Lead Mining Trail
you will need to park the car at the top of Moor Lane leading out
of Grassington to Yarnbury at N54 05.329 W001 58.702 From here you
will see an information board giving details of the Grassington
Lead Mining Trail.
The creation of the Grassington Moor Lead
Mining Trail has been carried out in partnership with the Yorkshire
Dales Millennium Trust using funds from the Millennium
Commission.
Galena is the mineralogists' name given to lead ore.
It does not commonly occur on its own but with a host of other
metallic minerals including sphalerite (zinc sulphide), and
malachite and azurite (both ores of copper). Also associated
with the metallic ores are the gangue minerals such as fluorite,
barite and calcite.
Galena is usually formed in
sedimentary rocks as vertical veins and less frequently as
horizontal deposits called 'flats'. The ores were deposited out of
mineral-rich saline waters that penetrated the joints and fractures
in the Carboniferous limestone on the Askrigg
Block.
By the end of the Carboniferous
and into early Permian times, the minerals were precipitated out of
solution with the hottest fluids producing the distinctive
cube-shaped crystals of galena which were later mined around
Grassington moor.
In order to log your find you
must walk to the Smelt Mill Chimney at the Earthcache co-ordinates
and find the answers to the following questions, then email them to
me through my Geocaching profile. You can also upload a photo of
you or your GPS at the chimney if you wish. Answers can be obtained
by reading the information boards that are located at various
points around the site:
-
As you stand next to the Chimney
you can see the long flues leading down to the Smelt Mill where
Galena was smelted, why did the flues have to be so
long?
-
What information point number
along the trail is the Smelt Mill Chimney?
-
In which years did the Earby
Mines Research Group carry out major repairs to the
chimney?
Any logs not fulfilling the
above request for answers to the required questions will be deleted
after seven days.