Lecture 3: Post-glacial History & Palaeoecology Flashcards
The Quaternary
- period of the ice ages (cooler)
- end of the tertiary (tropical climates)
Quaternary
- last ~2.6 mill years
- ice ages - progressive glaciations
- recent ice age 120,000 - 11,700 years ago - ……
Previous lecture : 650 mill years ago
This lecture: 2.6 million years
Dominant processes: glaciation and species migrations in response to climate change
Quaternary period
A cooler earth
(During quaternary)
- Gradual migration towards the polar regions of major continental land masses over time
- …
Causes of Repeated Glaciations
Astronomical forcing/’Milankovitch cycles’
- shape of earths orbit around the sun (eccentricty)
- tilt of the earth in relation to its plane of orbit (obliquity)
- Precession…..
…
Occurrence of tree genera in northwest Europe following progressive glaciations
Key ones: Sequoia, Magnolia
Native : Taxus to Ulmus
Quaternary Glacial Plant Refugia
- Plant populations in the glaciation areas are wiped out
….
Last glacial period
….
The Holocene
- present interglacial (warm) period
- last 11,700 years
- period when modern plant communities (as we know them today) developed
Holocene patterns of tree migration in the British Isles
- beech has bigger seed so slower at spreading
Palaeoecology
(Ecology of the past (not Palaeobotany))
- terrestrial sediment cores (lakes & bogs), ice cores, ocean sediments, tree rings
- fossil pollen
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