Cambrian Period, the first geologic period of the Paleozoic Era. It began 570,000,000 years ago and lasted 70,000,000 years. It is named for Wales (which the Romans called Cambria), where sedimentary rocks of the period were first recognized.
Earthquakes and volcanoes get all the press. But the landslides they trigger are often more devastating. What makes the ground suddenly rip downhill, taking trees and homes with it?
In "The Raiders of the Lost Ark," Indiana Jones competes with grave-robbing Nazis for the lost Ark of the Covenant. But what defined Dr. Jones as legit and the Nazis as grave robbers?