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Malham Cove yields icy secrets to diving scientist

April 25, 2002

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 was formed during the last glaciation, which ended 14,000 years ago, but Phillip Murphy 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."

Leeds, University of