Which of the following accurately describes 18O/16O ratios of the worlds oceans?
A) Because 18O evaporates more readily than 16O, the oceans have a higher relative abundance of 16O during warm periods and a more balanced ratio when there is less evaporation.
B) The higher the ratio of oceanic 18O/16O, the warmer the temperatures because the 16O will have been mostly evaporated from ocean waters.
C) During periods of colder temperature 16O is locked up in snow and ice and the oceans have a higher preponderance of 18O; during warmer periods the isotope ratio is lower.
D) The 18O/16O ratio is low during colder temperatures because temperatures are too low for evaporation to be effective and both isotopes remain in the ocean.
C
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Geologists have a very good record of the breakup of Pangaea because of ____
A)extensive guide fossils B)preservation of the continental crust from the Mesozoic C)the high rate of seafloor spreading during the Mesozoic D)extensive evaporite deposits E)magnetic anomalies preserved in oceanic crust
Methane (CH4 ), nitrous oxide (N2O), and chlorofluorocarbons (CFCs) are greenhouse gases
Indicate whether the statement is true or false
Los Angeles type smog is primarily a result of
A) smoke. B) fog. C) photochemical reactions. D) advected coastal fog laden with salt crystals.
Catastrophic subsidence into sinkholes tends to occur more often in areas underlain by ________.
A. basic freshwater flowing through sandstone B. basic saltwater flowing through sandstone C. basic freshwater flowing through limestone D. acidic freshwater flowing through limestone E. acidic saltwater flowing through sandstone