Gritstone- is a sedimentary rock composed of coarse
sand grains with inclusions of small pebbles. It is a coarser
version of sandstone.
As gritstone is a fluvial sedimentary rock it frequently shows
signs of cross-bedding or current bedding. It is quarried for
building material. British gritstone was used for millstones to
mill flour, grind wood into pulp for paper and grindstones to
sharpen blades.
Cross Bedding
In geology, cross-bedding refers to inclined sedimentary
structures in a horizontal unit of rock. These tilted structures
are deposits from bedforms such as ripples and dunes, and they
indicate that the depositional environment contained a flowing
fluid (typically, water or wind). This is a case in geology when
original depositional layering is tilted, and that the tilting is
not a result of post-depositional deformation.
Cross-bedding structures are formed in bedforms such as ripples
and dunes by the motion of sediment due to a flowing fluid.
Sediment grains bounce up the windward/upstream ("stoss") side of a
ripple, and then tumble down the lee side.
Cross-bedding can form in any environment in which a fluid flows
over a bed with mobile material. It is most common in stream
deposits (consisting of sand and gravel), tidal areas, and in
aeolian dunes.
Cross-bedded sediments are recognized in the field by the many
layers of "foresets", which are the series of layers that form on
the lee side of the bedform (ripple or dune). These foresets are
individually differentiable because of small-scale separation
between layers of material of different sizes and densities.
Cross-bedding can also be recognized by truncations in sets of
ripple foresets, where previously-existing stream deposits are
eroded by a later flood, and new bedoforms are deposited in the
scoured area.
The direction of motion of the cross-beds can show ancient flow
or wind directions. The foresets are deposited at the angle of
repose (~34 degrees from the horizontal), so geologists are able to
measure dip direction of the cross-bedded sediments and calculate
the paleoflow direction. This is important in reconstructing past
climate and drainage patterns: sand dunes preserve the prevalent
wind directions, and current ripples show in which direction the
rivers were moving.
Rock climbers still love the battery but in the 17th century the
remote area was a secret meeting place for nonconformist
worshippers, who refused to conform to the official prayer book and
services but were forbidden by law to worship as they chose. The
Fairy Battery is an important part of ecclesiastical history.
From the given coordinate's you will have a great view of the
Fairy Battery to log the cache please upload a photo of you or your
GPSr with the Fairy Battery in the backgound and E-Mail me the
answer to the following question's.
1) In which period was Gritstone formed .
2) Estimate the height of the rockface at it's highest.
Any logs with no photo may be deleted