The hill is volcanic in origin, like the Wrekin etc., formed of
narrow ridges of resistant Pre-Cambrian rock, thrust upwards by
movements deep down along the Church Stretton fault. This fault
runs from Staffordshire to South Wales and can be seen on OS maps
as a line of springs on this hill.
Contrary to a common misconception, Caer Caradoc has never been
a volcano in its own right, but is composed mainly of volcanic
rocks and is a product of volcanism. Its modern shape, which from
certain viewpoints appears to resemble a volcano, has been formed
by other natural processes.
Volcanic processes
Magma from the planet's mantle rises through the planet's crust,
if the magma from the mantle reaches the planet's surface it
behaves differently depending on the viscosity of the molten
constituent rock. Viscous (thick) magma produces volcanoes
characterised by explosive eruptions, while non viscous (runny)
magma produce volcanoes characterised by an effusive eruptions
pouring large amounts of Lava onto the surface. In some cases,
rising magma can cool and solidify without reaching the surface of
a planet. Instead, the cooled and solidified igneous mass freezes
within the crust of a planet to form an igneous intrusion.
Formation Of Rocks
When the magma cools it crystallises and forms rocks, the type
of rock formed depends on the chemical composition of the magma and
how rapidly the magma cools. Magma that reaches the surface to
become lava cools rapidly resulting in rocks with small crystals
such as basalt. Magma that remains trapped below ground in thin
intrusions cools slower than magma exposed to the surface and
produces rocks with medium sized crystals. Magma that remains
trapped in large quantities below ground cools most slowly
resulting in rocks with larger crystals - such as granite and
gabbro
Existing rocks that come into contact with Magma are often
melted by the heat, those that do not come into direct contact with
the magma do not melt fully but retain some of their original
structure - this process results in changes to the structure of the
original rocks changing them so much they become a new type of rock
- metamorphic rocks.
Fault Line's
In geology, a fault is a planar fracture or discontinuity in a
volume of rock, across which there has been significant
displacement along the fractures as a result of earth movement.
Large faults within the Earth's crust result from the action of
tectonic forces. Energy release associated with rapid movement on
active faults is the cause of most earthquakes, such as occurs on
the San Andreas Fault, California.
A fault line is the surface trace of a fault, the line of
intersection between the fault plane and the Earth's surface.
Since faults do not usually consist of a single, clean fracture,
geologists use the term fault zone when referring to the zone of
complex deformation associated with the fault plane.
The two sides of a non-vertical fault are known as the hanging
wall and footwall. By definition, the hanging wall occurs above the
fault plane and the footwall occurs below the fault. This
terminology comes from mining: when working a tabular ore body, the
miner stood with the footwall under his feet and with the hanging
wall hanging above him.
History
The summit is crowned by an Ancient British Iron Age or late
Bronze Age hill fort. It is this which the hill is named after -
Caer Caradog in Welsh meaning Caradog's fort. Local legend has it
that this was the site of the last stand of Caractacus against the
Roman legions during the Roman conquest of Britain, and that after
the battle he hid in the cave near its summit. Others say his last
stand was in the locality but that this was one of his
fortresses.
To log the cache please answer the following questions
1-Go to the given co-ord's, describe what you see and explain
the type of rock in this area.
2-On the summit there are a number of rock cluster's take a look
around them find a fault line and describe it to me.
A photo from the summit would be nice
Source Wikipedia