The phrase Pendle Hill is unusual in that it combines the
word for hill from three different languages.
In the thirteenth century the hill was mentioned as Pennul or
Penhul; apparently fromCumbric pen and Old English hyll, both
meaning "hill". The modern English hill was appended later, after
the original meaning of Pendle had become opaque. Pendle Hill is
the remains of a vast plateau (the delta of an ancient river) of
sedimentary rocks which lie over an ancient limestone bed. It is
composed mainly of Carboniferous Millstone Grit which offers some
protection from erosion by the actions of wind and rain - which
Pendle hill enjoys in great abundance all year round !
Even this protection is not enough to protect the hill from mud
slides and rock falls from the softer shale’s which lie under
the grit stone. At its extreme, features like "Burst Clough" (near
Worston) are formed when the pressure of water inside gives rise to
a great outpouring of water, mud and rock. Decomposition of
sphagnum moss on the hill has led to it being covered in peat.
Landslides on Pendle Hill
Another intense storm, of at least 56 mm of rain falling in a
2-3 hour period on the night of 29 September, 1999 affected the
south eastern flanks of Pendle Hill. The storm initiated a number
of small mass movements on the east facing slope of Pendle Hill and
along the sides of Ogden Clough. In places, Sphagnum mosses were
stripped and rolled back in depressions.The channels of both Ogden
Clough and its three north bank tributaries were all severely
eroded and pebbles and boulders were deposited on the valley floor
of the Clough.
What are landslides and how do they occur ?
Landslides have always existed on our planet.
Generallyclassified as mass movements of rock, debris, and soil
down a slope of land. While landslides are a naturally occurring
environmental hazard they have recently increased in frequency in
certain areas due to human activity. Although there are many
different causes of landslides, they all have two things in common.
According to Geologist’s “They are the results of the
failure of the soil and rock materials that make up the hill-slope
and they are driven by gravity."
Natural causes of Landslides
Earthquakes:
Seismic activities have always been a main cause of landslides
throughout the world. Any time plate tectonics move the soil that
covers them moves with it. When earthquakes occur on areas with
steep slopes, many times the soil slips causing landslides.
Furthermore, ashen debris flows caused by earthquakes can also
trigger mass movement of soil
Heavy Rainfall:
When sloped areas become completely saturated by heavy rainfall
many times landslides can occur. Without the aid of mechanical root
support the soil simply runs off when it contains too much
water.
Human causes of Landslides:
Clear Cutting: Method of timber harvesting which completely
removes all old growth timber from the area. This method is
hazardous because it destroys the existing mechanical root
structure in the area
Mining:
Mining operations that use blasting techniques often cause other
areas that are at the risk of sliding to slide due to vibrations
underthe soil.
To log the cache you need to upload a photo of you or your GPSr
at the trig point
And tell me what evidence you can see of landslides while on
your ascent.
Any logs with no photo may be deleted