Problem 24
$$ \text { Why is the rock cycle called a cycle? } $$
Problem 24
A geologist was studying rocks in a mountain range. She found a layer of sedimentary rock that had formed in the ocean. Hypothesize how this could happen.
Problem 25
A geologist found a sequence of rocks in which 200 -million-year-old shales were on top of 100 -million-year-old sandstones. Hypothesize how this could happen.
Problem 28
Suppose that a 4-m layer of plant matter was compacted to form a coal layer \(1 \mathrm{~m}\) thick. By what percent has the thickness of organic material been reduced?
