When the oldest rocks were formed

"Ancient Life"

"Middle Life"

"Recent Life"

Remains or impressions of ancient creatures

Animals without backbones

Oil, Coal, and Natural Gas

Masses or slow-moving rivers of ice that advanced across the land.

Scientists who study fossils

A large crater formed by a volcanic explosion or the collapse of a volcanic cone)

The wearing away of soil and rock by ice, water, or wind

Central region of Montana

Blustery, warm, dry winds that blow down the eastern slopes of the mountains and can raise temperatures as much as 50 degrees in several hours

An area on the inland side of a mountain range that is dryer because it is sheltered from rain-bearing clouds

Hot, molten material beneath the earth’s crust that forms igneous rock

Molten Rock

All along the backbone of the Rocky Mountains, from Kalispell in northwest Montana south through Utah, stretches a region of active earthquake faults