Lecture 9: Reconstructing the past

Question 1

continental drift

Answer 1

Wegener’s hypothesis suggested continents moved over time, similarities in rock and fossil type across Atlantic where layers of rocks are similar in different continents
- explained the shape of continents

Question 2

paleobiogeography

Answer 2

the distribution of fossils over space
- Provides one line of evidence for continental drift
- Largely rejected at first because it lacked mechanism

Question 3

plate tectonics theory

Answer 3

provides a framework for understanding the mapping of the ocean floor and how it demonstrates that the Earth’s crust is divided into “plates” that are slowly moving
- “Solid” earth is a thin crust that sits atop a semi-liquid asthenosphere
- The movement of the plates is small but measurable (inches/year)

Question 4

paleoclimatology

Answer 4

the reconstruction of climate through deep (geologic) time
- Critical area of science in the climate change research
- predicting climate change based on this

Question 5

tillite

Answer 5

sedimentary rock containing unsorted and unstratified rock material, created by glacial deposition
- common proxy for paleoclimate

Question 6

evaporite

Answer 6

sedimentary rock formed from a deposit of precipitated minerals caused by the evaporation of salt water (desertification aka drying up)
- common proxy for paleoclimate

Question 7

paleothermometers

Answer 7

reconstructing mean global temperatures, pieced together using temperature proxies
- Isotope variation in seawater correlates with temperature so do certain lipids produced by microbes (molecular fossils)
- Pollen grains, tree rings, the size of stoma in leaves also provide proxies