This rock is composed of laminated mudstone and siltstone with
greywacke sandstone. Skiddaw slate is a sedimentary rock, as first
identified on the slopes of Skiddaw in the English Lake District.
The base of this series is unknown. The thickness could, therefore,
amount to several thousand feet of sediment. These sediments were
formed about 500 million years ago by deposition in a shallow sea.
The series contains differing grain sizes and comprises grits,
flags, shales and mudstones. In some places, there is evidence of
intrusion of Skiddaw Granite into the Skiddaw Slates.
Skiddaw slate is used for building, in the Lake District. The
traditional buildings of Keswick and other settlements are almost
entirely of Skiddaw slate. The slate is also used for making
souvenirs, monuments, ornaments etc. Smaller fragments are used for
gravels, for ornamental pathways.
Mudstone is a mixture of clay and silt-sized particles. Terms
such as claystone and siltstone are often used in place of
mudstone, although these refer to rocks whose grain size falls
within much narrower ranges and under close examination these are
often technically mudstones.
Shale is often used to describe mudstones which are hard and
fissile (break along bedding planes). Marl is often used to
describe carbonate-rich soft mudstones.
Waterfall Formation
An important thing to remember about waterfalls is that that
they don't just 'exist', you may think that they have been here
forever but this is quite untrue, waterfalls exist because of
events that have happened on Earth many millions of years ago, such
as earthquakes, earth shifting and even volcanoes, as it turns out,
waterfalls are actually formed very slowly over the course of
several thousand years. A waterfall is purely a landform shaped by
the geomorphic process of river erosion.Perhaps the most famous
example of a waterfall is Niagara Falls.
Waterfall - Lifespan
Waterfalls will certainly be around for a long time, but, did
you know that they will eventually retreat and disappear altogther?
rock is slowly eroded by the constant flow of water, softer rocks
have eroded to create the falls in the first place, but the harder
remaining rock will also erode, albeit at a much slower rate, the
water flowing over these rocks falls into the 'plunge pool' and
creates a large gorge at the base of the falls, this constantly
eating into the rock and effectively undermining the rocks that
'hold the falls up' or infact the whole 'fall' itself. so in effect
the waterfall is actually retreating backwards.
No need to rush out now though! This isn't going to happen
quickly, and certainly not in this case, it is a very slow process
- as mentioned it takes thousands of years for a waterfall to form,
and not surprisingly it also takes just as long for it to
disintegrate. although you would hardly notice any changes to a
particular falls during your own lifetime, a good example, again,
would be Niagra Falls in Canada, which is actually retreating at
the rate of 3.3 feet (one meter) per year. The type of rock the
Earth is made up of where the waterfall is also affects waterfall
creation and the type of falls that is created there, here we will
look at the area around Foyers and it's geology showing what you
now see here today.
To log the cache please e-mail me the answers to the following
questions
1-From the cache site using your GPS tell me how many feet above
sea level you are.
2-Find a piece of slate and a piece of mudstone and tell me the
difference in texture.
A photo of the falls would be nice