Past Environments Flashcards
1
Q
What are epicontinental seas?
A
When sea levels are very high and water forms a sea in the continental body, very biodiverse.
2
Q
How can past environments be interpreted?
A
- Sediments (relating to present day distribution, looking at sediment structure from rocks)
- Fossil content (e.g. sea/terrestrial, compare to today)
- Distribution of climatically sensitive sediments and fossils (warm/cool vs wet/dry)
- Isotopes (light vs heavy, e.g. calcium, boron)
- Environmentally influenced characteristics of organisms (e.g. growth rings of trees, different shell shapes in different salinity, fewer stomata means higher CO2 level)
3
Q
How can growth rings of trees interpret past environments?
A
Climate, there will be no growth rings if it is a tropical environment because the trees are not stopping growing in winter.
4
Q
What do boron isotopes tell us about past environments?
A
Boron isotopes tell how acidic the ocean was.
5
Q
When did Pangea split?
A
Late Jurassic
6
Q
When were sea levels very high?
A
During Triassic, Jurassic and Cretaceous.
7
Q
What are characteristics of polar dinosaurs?
A
- Lived in cold (ice heave and polygon structures associated with bones)
- Experienced polar winter
- Possible evidence for migration in the North but not possible in the South
- Large eyes adapted for polar winter
- No evidence for hibernation (no LAGs)
8
Q
What is ice heave?
A
An upwards swelling of soil during freezing conditions
