
Volcanic Winter: When the largest volcanic eruption of the past two million years occurred 75,000 years ago, a shield of debris formed and deflected the sun's rays. (S3, ep 5)

Dam Break: Dams are a marvel of engineering, but when the South Fork Dam gave way during a storm in 1889 - killing 2,200 people - the damage was catastrophic. (S3, ep 6)