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Physical Geography 24-25 > Quaternary glaciations and landscapes > Flashcards

Quaternary glaciations and landscapes Flashcards

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1
Q

What is the Quaternary Period?

A

The last 2.6 million years marked by repeated glacial and interglacial cycles.

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2
Q

What drives Quaternary climate changes?

A

External (orbital changes, solar output) and internal (greenhouse gases, ocean currents) forcing.

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3
Q

What are the Milankovitch cycles?

A

Orbital variations: eccentricity (100k, 400k), obliquity (41k), and precession (19k, 23k).

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4
Q

What is the Mid-Pleistocene Transition?

A

Shift from 41kyr to 100kyr glacial cycles around 800,000 years ago.

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5
Q

How do ice cores inform us about past climate?

A

They provide CO2, CH4, and temperature records over 800,000 years.

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6
Q

What are stable oxygen isotopes used for?

A

To infer temperature and ice volume from marine and ice cores.

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7
Q

What is δ18O?

A

A measure of the ratio of 18O to 16O relative to SMOW, indicating glacial/interglacial states.

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8
Q

What are Marine Isotope Stages (MIS)?

A

Numbered warm (odd) and cold (even) periods in the Quaternary based on δ18O.

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9
Q

What is a Heinrich Event?

A

Massive iceberg discharge events leaving ice-rafted debris in marine sediments.

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10
Q

What are Dansgaard-Oeschger (D-O) events?

A

Rapid warming episodes (~1000-2000 yrs apart) during glacial periods.

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11
Q

What is the ‘bipolar seesaw’?

A

A climate pattern where warming in the Southern Hemisphere coincides with cooling in the Northern Hemisphere.

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12
Q

What are feedback mechanisms?

A

Processes that amplify (positive) or reduce (negative) climate changes.

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13
Q

What is the effect of CO2 on Quaternary glaciations?

A

Lower CO2 levels promote glaciation; higher levels prevent it.

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14
Q

What is sub-Milankovitch climate variability?

A

Climate changes occurring on timescales shorter than orbital cycles.

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15
Q

What is thermohaline circulation?

A

Ocean circulation driven by differences in temperature and salinity.

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16
Q

What caused the Younger Dryas?

A

Freshwater from Lake Agassiz disrupted Atlantic circulation, causing abrupt cooling.

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17
Q

What dating methods are used in Quaternary science?

A

Radiocarbon, luminescence, cosmogenic nuclides, varves, and stratigraphy.

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18
Q

What are varves?

A

Annual layers in lake sediments used for dating.

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19
Q

What is radiocarbon dating?

A

A method using 14C to date organic materials up to ~50,000 years old.

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20
Q

What is optically stimulated luminescence (OSL)?

A

Dating method that determines the last time sediment was exposed to sunlight.

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21
Q

What are trimlines?

A

Erosional marks indicating former ice sheet thickness.

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22
Q

What is morphostratigraphy?

A

Classification of landforms based on their relative age and morphology.

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23
Q

What is lithostratigraphy?

A

Stratigraphy based on sediment characteristics and structure.

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24
Q

What is biostratigraphy?

A

Stratigraphy based on fossil content like pollen or beetles.

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25
What are proxy data?
Indirect indicators of past environments like pollen, isotopes, and sediment properties.
26
What are chironomids?
Non-biting midges whose remains reflect past temperature and water conditions.
27
What are coleoptera?
Beetles used in mutual climatic range reconstructions.
28
What is the Younger Dryas?
A cold period around 12.9–11.7 ka marked by abrupt cooling in the North Atlantic.
29
What is the 8.2 ka event?
A sudden cold event triggered by final drainage of Lake Agassiz.
30
What is the Holocene?
The current interglacial epoch, started ~11,700 years ago.
31
What is the Little Ice Age?
A cold period from ~1300 to 1850 AD characterized by glacier advance and cooling.
32
What is the Medieval Warm Period?
A warm period from ~800 to 1200 AD marked by reduced sea ice and Norse settlements.
33
What are pluvial lakes?
Large lakes formed in arid regions during wetter glacial periods.
34
What is loess?
Wind-blown silt deposited in glacial periods.
35
What are pingos?
Ice-cored hills in permafrost regions.
36
What are ice wedges?
Vertical wedges of ice formed by ground cracking and infilling with meltwater.
37
What is patterned ground?
Soil patterns formed by freeze-thaw processes in periglacial environments.
38
What is aeolian sediment?
Sediment transported and deposited by wind.
39
What is a moraine?
Accumulation of glacial debris marking former glacier limits.
40
What is a drumlin?
Streamlined hill formed under glacial ice, indicating flow direction.
41
What are flutings?
Long, narrow grooves carved by glacier movement.
42
What is the Anthropocene?
A proposed epoch marking significant human impact on Earth's systems.
43
What is greenhouse gas forcing?
Warming effect due to increased atmospheric GHGs like CO2 and CH4.
44
What is the IPCC?
Intergovernmental Panel on Climate Change, assesses climate science and risks.
45
What is the current CO2 concentration?
Over 420 ppm, the highest in 800,000 years.
46
How do humans influence the carbon cycle?
Fossil fuel burning, land-use change, and deforestation.
47
What are future climate projections?
GCMs predict 2–3°C warming over the next century under current emissions.
48
What is RCP 8.5?
A high emissions scenario predicting severe warming.
49
What is GISP2?
A Greenland ice core providing 110,000 years of climate data.
50
What is EPICA?
European Project for Ice Coring in Antarctica, extends 800,000-year climate record.
51
What is the Vostok ice core?
A core from Antarctica showing past GHG and temperature links.
52
What is the significance of MIS 11?
A long interglacial often compared to the Holocene.
53
What is cryosphere feedback?
Snow and ice changes that enhance climate shifts via albedo.
54
What is the role of tectonics in glaciation?
Uplift and continental arrangement affect atmospheric and ocean circulation.
55
What is regolith removal?
Loss of unconsolidated substrate, possibly allowing thicker ice sheets.
56
What are 'Heinrich layers'?
Sediments in ocean cores marking massive iceberg discharges.
57
What causes Heinrich events?
Ice sheet instability and ocean warming leading to iceberg surges.
58
What is the 'salt oscillator' model?
THC variations linked to salinity shifts due to iceberg melt.
59
What is isostatic adjustment?
Crustal rebound following glacial retreat.
60
What is a bolide impact?
Meteorite event hypothesized to cause Younger Dryas cooling.
61
What is 'stratigraphic superposition'?
Oldest layers at the bottom, youngest at the top in undisturbed sequences.
62
What is XRF?
X-ray fluorescence, a geochemical tool for element analysis in sediments.
63
What is LOI?
Loss on ignition, measures organic content by burning.
64
What are sapropels?
Organic-rich marine sediments from anoxic events.
65
What is the Gelasian?
Base of the Quaternary, ~2.588 million years ago.
66
What is a GSSP?
Global Stratotype Section and Point, marks epoch boundaries.
67
What is palynology?
Study of pollen to reconstruct past vegetation and climate.
68
What is a lithofacies?
A body of rock with specific sedimentary features indicating depositional environment.
69
What is mutual climatic range?
Temperature reconstruction method using beetle species distributions.
70
What is the Loch Lomond Stadial?
A cold phase in Britain ~12.9–11.7 ka.
71
What is the North Atlantic Deep Water (NADW)?
A dense water mass formed in the N Atlantic, part of THC.
72
What are cosmogenic nuclides?
Isotopes formed by cosmic rays, used for exposure dating.
73
What is the Younger Dryas type site in the UK?
Croftamie.
74
What is the significance of Lake Agassiz?
Its drainage triggered abrupt cooling events like the YD and 8.2 ka.
75
What is XRD?
X-ray diffraction, identifies mineral structure in sediments.
76
What is deuterium?
A heavy hydrogen isotope used in ice core analysis.
77
What are chironomid zones?
Temperature-based classifications of midge assemblages.
78
What is the Holocene Thermal Maximum?
Warmest phase of the Holocene around 9–5 ka.
79
What is the Neoglacial?
A cooling trend after the Holocene Thermal Maximum.
80
What is the current sea-level rise?
~20 cm from 1850 to 2005.
81
How much warming since 1850?
~0.9°C globally.
82
What is TOC?
Total Organic Carbon, used to infer productivity and carbon sources.
83
What is the mutual climatic range method?
Uses overlapping temperature ranges of species to reconstruct past climate.
84
What are marine terraces?
Wave-cut platforms uplifted by tectonics or sea-level changes.
85
What is aeolian activity?
Wind-driven sediment transport, common during glacial periods.
86
What is an interstadial?
Short warm period within a glacial period.
87
What are 'fullerenes'?
Carbon molecules linked to bolide impacts.
88
What are annual glacier layers?
Used in ice cores for incremental dating.
89
What is the Maunder Minimum?
Low sunspot activity phase linked to Little Ice Age cooling.
90
What is tephrochronology?
Dating method using volcanic ash layers.
91
What are amino acid racemization techniques?
Used for dating based on protein degradation.
92
What is the impact of ice-rafted debris?
Indicates iceberg discharge and ocean circulation changes.
93
What are frost polygons?
Polygonal ground patterns from repeated freeze-thaw cycles.
94
What is peat?
Accumulated organic-rich sediment used for palaeoenvironmental reconstruction.
95
What are GCMs?
Global Climate Models used to simulate past and future climate scenarios.

Physical Geography 24-25 (5 decks)

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