Geo 105, Main points for Earthquakes for Feb 5

Review of Sea Level Changes

• Variations at all "times scales"
  • "Short" time scale variations presuambly due to
    ice ages, change in ice volume in continental-scale ice sheets
  • and "Longer" time scael changes, up to a million years....
    caused by cycles in orbital parameters of Earth about Sun?
  • "Long" time scale changes, e.g. high sea level in Cretaceous,
    caused by plate tectonics? the breakup of continents and accelerated spreading?

Impacts

• An important process in history of Solar System
• Study of Moon shows intense bombardment in the early history
  but fewer impacts in last couple of billion, repeat Billion, years
• Impacts still do happen on Earth
  in rare cases, can extract the orbit of objects that hit earth
• Did a large impact cause the Cretaceous-Tertiary mass extinction?
  
• Great accumulation of evidence that one (or more) large impacts
  did occur at this boundary
• But detailed studies of fossils show a rather complicated pattern
  of extinction
• What would actually cause extinctions?
  Most people think that dust in atmosphere would alter climate, lets look at climate...

Greenhouse effect (look at review for Feb. 10)

• Figure 1
• Figure 2
• Figure 2