Chemical analyses of calcite composing the fossil microscopic shells of some marine plankton serve as proxy records of:
A) sea level.
B) ocean temperature.
C) glacial ice volume.
D) both B and C.

Question

Quizplus · Accepted Answer

The chemical composition of calcite in fossil microscopic shells of marine plankton can provide information about both ocean temperature and glacial ice volume, making D the correct answer. By analyzing the ratios of oxygen isotopes in the calcite, scientists can determine the temperature of the ocean at the time the shells were formed. Additionally, the amount of heavy oxygen isotopes in the calcite can provide information about the volume of glacial ice during the time the plankton were alive, as heavier isotopes tend to be locked up in ice. However, calcite composition is not a reliable proxy for sea level.

Chemical Analyses of Calcite Composing the Fossil Microscopic Shells of Some