Clark et al., 2010 Flashcards
Clark et al., 2010 (timings)
What was done?
Reconstructed BIIS from mapping paleoecological data in the BRITICE database alongside cosmic (imminence) dating to determine age maps of retreat in the UK between 27 and 15 ka BP.
Remote sensing data presented maps of moraines, meltwater channels, eskers, and drumlins and a methodology of how to interpret and bring them together.
For the continental shelf, numerous large moraines were discovered recording an extensive pattern of retreat stretching from SW Ireland to the Shetland Isles.
What is cosmogenic nuclide dating?
Cosmogenic nuclide dating uses the interactions between cosmic rays and nuclides in glacially transported boulders or glacially eroded bedrock to provide age estimates for rock at the Earth’s surface.
Cosmogenic nuclides are rare nuclides that form in surface rocks because of bombardment by high-energy cosmic rays.
When particular isotopes in rock crystals are bombarded by these energetic cosmic rays neutrons, a spallation reaction results.
Spallation reactions are those where cosmic-ray neutrons collide with particular elements in surface rocks, resulting in a reaction that is sufficiently energetic to fragment the target nucleus.
These cosmic rays do not penetrate deep into the earth’s surface. This is important for glacial geologists, as it means that surfaces that have had repeated glaciations with repeated periods of exposure to cosmic rays can still be dated, as long as they have had sufficient glacial erosion to remove any inherited signal.
Clark et al., 2010 (timings)
What was found?
27 ka- maximum extent
23 ka- ice ice withdrawing along N boundaries and advanced along southern
19 ka- widespread marine based ice loss in both North and Irish Sea
17 ka- ice no longer marine- all terrestrial- Final collapse of all marine sectors occurred by 17 ka BP and with most margins beginning to back-step onshore.
There is a lack of understanding when the ice bridge of the UK-Norway collapsed.
What did the BIIS deglaciated in response to?
Rising temperatures and a rising sea level (driven by melting of other ice masses).
(Clarke et al., 2010).
What global sea level could the ice volume from the last glacial ice sheet raise?
Ice volume sufficient to raise global sea level by ca 2.5 m when it melted.
(Clarke et al., 2010).
