Stainforth force
The waterfall begins as a series of small cascades followed by a
final slightly larger one River Ribble, the waterfall plunges off
Carboniferous Great Scar Limestone that was laid down in a clear
sub-tropical sea 330 million years ago.
The water bounces onto rocks belonging to the Lower Ordovician
(Arenig) Ingleton Group laid down some 500 million years ago. The
time gap between the horizontally bedded limestone and the steeply
dipping turbidite sandstones is about 170 million years. Recently
more research on the age of the Ingletonians suggest that they may
be Precambrian after all !
The geology of the Yorkshire Dales is perfect for supporting
waterfalls. The spectacular landscape is a result of the area's
geololical history with much of the Yorkshire Dales National Park
covered in carboniferous limestone which is interspersed with
shales, gritstones and sandstones. Natural landshift which created
the topography of the area during the great ice age and subsequent
erosion of the softer stones has caused rivers and becks to form
waterfalls all over the dales. Some are little more than a few
inches high, many less than the height of an adult person.
Waterfall Formation
Typically, a river flows over a large step in the rocks that may
have been formed by a fault line. As it increases its velocity at
the edge of the waterfall, it plucks material from the riverbed.
This causes the waterfall to carve deeper into the bed and to
recede upstream. Often over time, the waterfall will recede back to
form a canyon or gorge downstream as it recedes upstream, and it
will carve deeper into the ridge above it.
Often, the rock stratum just below the more resistant shelf will
be of a softer type, meaning that undercutting due to splashback
will occur here to form a shallow cave-like formation known as a
rock shelter or plunge pool under and behind the waterfall.
Eventually, the outcropping, more resistant cap rock will collapse
under pressure to add blocks of rock to the base of the waterfall.
These blocks of rock are then broken down into smaller boulders by
attrition as they collide with each other, and they also erode the
base of the waterfall by abrasion, creating a deep plunge pool or
gorge.
Streams become wider and shallower just above waterfalls due to
flowing over the rock shelf, and there is usually a deep pool just
below the waterfall because of the kinetic energy of the water
hitting the bottom. Waterfalls normally form in a rocky area due to
erosion.
Waterfalls can occur along the edge of a glacial trough, whereby
a stream or river flowing into a glacier continues to flow into a
valley after the glacier has receded or melted. The large
waterfalls in Yosemite Valley are examples of this phenomenon. The
rivers are flowing from hanging valleys.
To log the cache please upload a photo of you or your GPSr with
the falls in the backgound and E_mail me the answer' the following
questions.
1) How many cascade's are there to the falls.
2) Estimate the height of the final cascade
Any logs with no photograph may be deleted