Multiple choice Why is America so rich in coal? peat had time to accumulate & get slowly compacted igneous rock had time to accumulate & get slowly compacted limestone had time to accumulate & get slowly compacted marine animals had time to accumulate & get slowly compacted Reveal answer Fill a bubble to check yourself A Correct answer Explanation Coal is formed from the remains of ancient swamp plants. Peat is the precursor to coal, which accumulates in oxygen-poor environments and undergoes compaction over geological time.