Author Question: How do geologists determine the number of ice ages and when they happened? What will be an ideal ... (Read 50 times)

jake · **on:** Jul 16, 2018

How do geologists determine the number of ice ages and when they happened?

What will be an ideal response?

Question 2

Because glacial ice is a natural, consolidated aggregate of minerals, it is considered to be a rock. Explain what type of rock it is: igneous, metamorphic, or sedimentary.

What will be an ideal response?

jaymee143 · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

The best record of the timing of past ice ages, although indirect, comes from measuring the ratio of oxygen isotopes in tiny foraminifera shells that accumulated in successive layers of deep-sea sediment. The ratio of the 18O to 16O is strongly affected by the amount of water that is evaporated from the ocean and stored on continents as glacial ice. The isotope ratios in layers of different ages can, therefore, track the occurrence of past ice ages.

Answer to Question 2

Glacial ice is a metamorphic rock because it forms from the recrystallization of snow due to increasing pressure with burial beneath the glacier surface.