Transcript Limestone Pavement

CaCo3
limestone
Carbonation ( chemical weathering)
Semer water, Yorkshire Dales
Carbonic acid in rainwater dissolves limestone.
CaCo3 + H20 + CO2
Limestone
+
carbonic Acid
Ca(HCO3)2
Calcium bicarbonate
Limestone Pavement
Limestone Pavements are slabs of rock (clints), separated vertical
cracks (grikes).
Grikes have developed by weathering and enhanced solution along
joints.
Shake Holes
A shakehole is a depression in the limestone landscape. They are formed where
surface water washes boulder clay down into cracks or fissures in the limestone under
the boulder clay.
Resurgent Spring
When a stream disappears in
a karst area, it works its way
down…
….to a level of
impermeable rock and
reappears as a spring.
During the last ice age huge ice sheets scraped away
the soil-covered spurs in many valleys and steep cliffs
of bare rock were exposed.
Scars
Scree slopes
of broken rock
form below
them.
Bedding Planes
Malham Cove, Yorkshire
Dales
The bedding planes are the
horizontal layers formed as the
rocks were compressed under
deposits formed above, about
300 million years ago.
During the meltwater phase of the
last ice age, underground streams
eroded vast caverns as huge
volumes of water travelled through
the limestone.
Gorge
Trow Gill, Ingleborough.
Sometimes the roofs of these caverns can collapse.
Dry Valleys
During the last ice age the limestone was frozen to great
depths. When the ice melted it carved out valleys over the
frozen rock. When surface water is able to infiltrate down
through the rocks and the dry valleys were left with no surface
water.
Erratics
During the ice age large boulders
were carried within the ice sheet.
When the ice melted these
boulders were left sitting on the
surface.
They are called erratics because they are totally different
from the bed rock of the area
Gaping Gill, Yorkshire Dales.
Swallow Holes or Sink Holes This is where water falls 110m
below the ground. It is the UK’s
(smaller).
highest underground, unbroken
waterfall.
A stream travelling over an impermeable rock
will very quickly disappear when it has to travel
over limestone. This what pot-holers climb
down.