Malham
Cove yields icy secrets to diving scientist
One
of the most well-known features of the Yorkshire landscape
is nearly four times older than previously thought, cave
diver and earth sciences technician Phillip Murphy has
established.
Scientists
believed that Malham Cove (pictured above) was
formed during the last glaciation, which ended 14,000
years ago, but Phillip Murphy (pictured below)
has collected a stalactite sample from the flooded cave
system which proves the cove must be at least 50,000 years
old.
"As
one of the few cave-diving earth scientists in the UK,
I can reach otherwise inaccessible areas," he said. "I
heard that a fellow diver had come across a speleothem
– as stalactites and stalagmites are collectively
known – in an underwater cave. Speleothems normally
form once a cave passage is no longer flooded, so to find
one underwater means that some change has taken place
to flood that cave system."
Malham
Cove is a 'step' formed by glaciers and waterfalls. The
area is criss-crossed with cave systems, created by water
dissolving the limestone rock. The valley below the cove
was gouged out by a glacier, draining the cave system
of its water. Then a later glacier brought sediment over
the lip of the cove, pooling the site with silt which
caused the cave system to once again fill with water.
The
speleothem provides the key to dating these events, as
Phillip Murphy explains: "Speleothems don't form during
glacial periods, as freezing temperatures above and below
ground mean there is no moving water. So the speleothem
discovered in the Malham cave system must have been formed
during a warm period between the glaciation which formed
the cove and another which deposited the silt. When the
ice melted, the silt then caused the caves to flood."
University
of Liverpool archaeologist Alf Latham helped him date
the speleothem and found it to be around 26,000 years
old.
This
proves that the cave system was re-flooded after the last
ice age when, between 23,000 and 20,000 years ago, glaciers
covered the region creating the Dales landscape we know
today. It also proves that the initial formation of Malham
Cove must have taken place over 50,000 years ago, predating
the last ice age and the warm period known to precede
it.
Phillip
Murphy: "Although glaciers played a major role in forming
the Dales landscape, they also scoured the area clean,
leaving little surviving data on the surface. The discovery
of this speleothem shows that important evidence still
exists underground, especially in the flooded caves where
the only access is by diving."
