Multiple choice

If sandstone covers the shale, and is then covered by a(n) ______ rock layer, oil can be mined.

  1. muddy

  2. igneous

  3. sedimentary

  4. impermeable

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Oil and gas often migrate upward through porous rock until they hit an impermeable layer (a cap rock), which traps the hydrocarbons in a reservoir.