A recording of a talk given by David Webster to the Islay Natural History Trust on 22 April 2024.
The Garvellach Islands and Islay expose a magnificent section of the glacial Neoproterozoic Port Askaig Formation. Although part of the Dalradian it is relatively undeformed and contains an extraordinary amount of glacial features including spectacular glaciotectonic ‘rafts’ as well as a sequence at the base recording the transitional onset of glaciation at the start of the Cryogenian - which is a prime candidate for a global ‘golden spike’ or GSSP. The snowball earth concept will be discussed and how the succession here fits (or doesn’t) with that model. New work on the provenance of the exotic granitic clasts will also be covered.
The talk will introduce the new Geological Society of London ‘Memoir’ on the Port Askaig Formation - currently being produced by a large multi-disciplinary team led by Tony Spencer and Ian Fairchild.

David is a retired oil-company geologist who juggles his time between Glasgow and Islay. He graduated from Oxford University in 1976 and in later life did Masters degrees in Environmental Management and on the geology of the Colonsay Group on Islay. He has written two guidebooks to the geology of Islay, Jura and Colonsay. He is currently the Secretary of the Geological Society of Glasgow and is a Board Member of the Fossil Grove Trust. Previously he was Secretary of the Islay Natural History Trust.

свернуть