GEOG 2210 Lecture Notes - Lecture 5: Tephra, Crater Lake, Barcode
9 Nov 2017
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Document Summary
Oldest are in coastal margins --> due to plate tectonics. Silt-sized grains that get transported in dust storms then deposited. In canada was in ice, when the glaciers melted the deposits moved. Trapped air bubbles --> figure out the composition of the atmosphere when the ice was formed. Don"t usually have to cut down the tree. More snow = less growth = smaller rings (shorter growing season results in less growth. Some trees draught sensitive, some trees temperature sensitive. Tropical trees live shorter live than higher attitude trees. Similar to tree rings is goduck --> species of clam. Take thin section along hinge of shell to analyse. Ice core --> mostly longer period, can be annual. Lake sediment --> goes back millions of years. Need to know when a record was formed in order to infer accurate history of climate: Based on the radioactive decay of unstable isotopes.
