GLY 102 Lecture Notes - Lecture 7: Foraminifera, Ice Rafting, Terrigenous Sediment
11 Sep 2017
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Review
Ice cores – provide past greenhouse gas concentration, provide history of volcanic activity, they
record temperature and precipitation and goes back about 100 million years.
Isotopes show pass temperature
• Isotopically lower in cold times
• You can measure methane and co2 with isotopes
• The natural oscillations of climate shown in ice core records are due to what climate
forcing? – Earth orbits around the sun
• Volcanism- not a cycle., random
New information
• Many archives of past climate change
o Tree rings
o Loess (wind-blown dust)
o Cave speleothem
o Lake sediments
o Glacier deposits
o Ocean sediments
• Tree rings
o Like stack of traffic cones
o Tree core, like an ice core
o Count the rings to get the time
o Width of the tree rings can match with the climate
o Grows more with warm summers, less with cold summers
o Summer Temperatures
o One year increments, they grow one ring at a time
o Thicker or thinner with summer temperature
o Dead trees can be overlapped compared with living trees to about 12,000 years
• Loess (wind blown dust)
o During the ice age, Alaska was very dusty
o In china, loess records glacier and interglacial cycles, storminess and changes in
atmospheric circulation
▪ Warm period- red layer
▪ Cold period- light color
o The yellow river is yellow due to the dust
o These layers record warm and cold times
o Warm periods called interglaciation
• Caves speleothem
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