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discovering ireland > worksheet 8 > Flashcards

worksheet 8 Flashcards

1
Q

when did the polar ice caps appear in south pole

A

40-45 mya in middle-late eocene (part of the paleogene)

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2
Q

when did ice caps appear in the north pole

A

beginning of quaternary period, ~2.5 mya

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3
Q

what is the name of the ice sheet in the south

A

antarctic ice sheet

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4
Q

what is the name of the ice sheet in the north

A

northern ice sheet

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5
Q

what could have caused the present ice house we are in

A

co2 being taken out of atmosphere by the uplift and erosion occuring when himalayas were formed (india and eurasian plate colliding)

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6
Q

what is necessary for ice sheets to form at the poles

A

continental landmasses

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7
Q

what causes advances and retreats of ice caps throughout the quaternary period

A

variation in surface temps

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8
Q

are we in a glacial or interglacial period

A

interglacial

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9
Q

is sea level higher in glacial or interglacial periods

A

interglacial bc water is not in ice sheetsw

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10
Q

what is the difference in sea level between glacial and interglacial periods

A

~100 m higher in interglacial

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11
Q

what causes glacial-interglacial cycles

A

glacial periods become interglacial periods when northern hemisphere’s summer solar insolation increased

eccentricity which also has periodicity of 100,000 years also has effect. as eccentricity increases, orbit is more egg shaped.

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12
Q

when was the most recent glacial cycle (aka ice age)

A

10,000-37,0000 years ago

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13
Q

what is EISC and how big was it

A

eurasian ice sheet complex

about 4500 km

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14
Q

how did the EISC change throughout time

A

3 distinct nucleation points (UK/Ireland, barents sea, scandinavia) which is grew and collapsed from

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15
Q

what was the effect of EISC on shorelines

A

shorelines advanced as sea level fell so it varied throughout the ice age

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16
Q

what geomorphological features formed by glacial erosion are still in ireland

A
  • u-shaped valleys
  • nunataks
  • roches moutonnees
17
Q

what is a u shaped valley

A

formed by glacial erosion

v-shaped river valleys were eroded to form u-shaped glacial valleys

18
Q

what are nunataks

A

formed by glacial erosion

“glacial islands” at tops of ridges, mountains or peaks that were not covered with ice or snow either at edge of ice sheet or within it (poked out the top of glaciers)

19
Q

what are roches mountonnees

A

formed by glacial erosion

bumps or hills of bedrock that are asymmetric with short steep lee side and long gentle sloping stoss side that show glacial movement (saw in killiney)

20
Q

what geomorphological features and deposits formed by deposition beneath or at the margins of ice sheets are common in ireland

A
  • moraines
  • esker
  • drumlins
21
Q

whats a moraine

A

accumulation of debris formed at margin of glacier

22
Q

whats an esker

A

subglacial stream deposits that form sinuous elongate (long curvy) ridges of sand and gravel

23
Q

whats a drumlin

A

long ridge formed by ice moving over unconsolidated sediments (similar to roches by made of till)

24
Q

what geomorphological features are associated with post glacial periods like the holocene

A
  • rias or fjords
  • drowned drumlins
25
Q

whats a fjord/rias

A

drowned valleys that were covered when the sea level rose

26
Q

what was the inferred pattern of ice flow of the ice sheet that covered Ireland/Britain (BRITICE)

A

flowed from high -> low ground

27
Q

when was the BRITICE at max southern

A

23,000 years ago

28
Q

what topography does the maximum extent of BRITICE align with

A

the present day shelf in the ocean as it restricted any more movement (water was too deep to ground any futher)

29
Q

what geomorphic feature found offshore in the atlantic were used to infer the western limits of the ice sheet

A

moraines on the current continental shelf

30
Q

what are trough mouth fans and where are they found

A

fan/delta accumulations of sediment that develops at the end of glacier troughs on the end of continental shelves

form bc sediment is fed to the slope which ends and the sediment accumulates in fan shape

31
Q

what are erratics and what are they formed of

A

large boulders transported by ice sheets

formed by hard igneous rock because if it is weaker than it will be ground up

discovering ireland (10 decks)

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