the story of the norber erratics. the story unfolds on a hillside in yorkshire large boulders of...
TRANSCRIPT
The Story of the
Norber Erratics
The story unfolds on a hillside in Yorkshire
Large boulders of gritstone perch on plinths of limestone
Together they tell a story which has been 16,000 years in the making
Their exact location is here….
North of Austwick in the Yorkshire Dales National Park
The boulders are made of gritstone carried by a glacier
from the floor of Crummack Dale about 3 kms to the north
The hillside was scoured by the ice revealing a
pavement of limestone
..on top of which, as the ice retreated, it
deposited its load of gritstone boulders
For 16,000 years the limestone pavement has slowly weathered, dissolved by mildly
acidic rainwater ….
..except where it has been protected by the gritstone boulders lying on top
Gritstone erratic
Plinth of limestone
Height of the pavement at the end of the Ice Age
Gritstone erratic
Plinth of limestone
Height of the pavement today
Solutional weathering since the Ice Age
How long can their plinths survive?
But …..