1. The Story of the Norber Erratics

2. 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

3. 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

4. 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

5. 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

6. Gritstone erratic Plinth of limestone Height of the pavement at the end of the Ice Age

7. Gritstone erratic Plinth of limestone Height of the pavement today Solutional weathering since the Ice Age

8. How long can their plinths survive? But …..