Cryosphere 2- connections Flashcards
how thick was the ice sheet over Scandinavia and UK?
Sacndinavia-2.5km
UK- 1km
What was the extent of the laurentide at the LGM?
Past Newyork and midwest towards the rockies
What does LGM stand for?
Last Glacial Maximum
Why hasnt japan even had glaciation?
even though bay water can freeze and receive 5m snow due to latitudinal position this is overcome in summer
Who was reposible for the first evidence of a quaternary ice sheets?
Louis Agassiz - perched boulders (erractics which couldnt have been placed by flood)
What is glacial erratic deposition?
Boulder plucked from bedrock or fall from nunatak which can very carried 10’s-100km’s and then deposited when glacier retreats
What is an erratic?
a rock that has been deposited in an area in which its own minerology doesn’t match the area of deposition
What is an example of erratics in birmingham?
Cotteridge park
What allowed the quaternary ice sheets to grow?
positive feedback from albedo
Where did the LGM stop?
Walsall/ Dudley
What is provenance?
the source/ origin of an erratic
What was the extent of the Devensian till sheet defined as by Powell 2000?
a line from north Dudley, through Walsall to Sutton Coldfield
What are the glacial depositional landforms?
Lateral, medial, terminal, ground, end and recessional moraines
Outwash
Drumlin
What are 2 examples of erosional and directional indicators of glaciation?
Striations
Gauges
What are striations?
scratch marks on the rock surface formed by fine grain material scraping surface.
What are gauges?
when large cobble size material is pressed onto rock with great pressure this shatters bedrock
What is isostatic depression?
when overlying weight of ice causes rock to dip down
What is isostatic rebound?
when ice retreats the ground will slowly start to rise again
Where is a present day example of isostatic rebound?
James Bay Canada
Why might relative sea level next to ice sheets be higher?
ice sheets are so big they can have their own gravitational pulling up the surrounding ocean
What will variations in O18 be like on 41Ka cycle and 100ka?
frequent fluctuations for 41
large peak and trough 100ka
How did co2 ppm over last 5 million years due to sediment cores?
330-400ppm to 270-280ppm
What has happened to glacial severity over last 0.7Ma?
have become more severe
How do the Milankovitch cycles interact with each other?
100ka super cycle with 41 and 23ka cycles nested in between
How long was the quaternary?
2.6million years
