Geological Eras Montana History Precambrian Era 4 6

Geological Eras Montana History

Precambrian Era 4. 6 billion – 544 million years ago First one-celled creatures Montana covered by a large sea Covers almost 90% of the history of Earth

Precambrian Continued Different layers of sedimentary rock were settled over millions of years, creating layers in the Earth Within these layers, we find fossilized remains of plants and animals The first organisms were microscopic bacteria, which lived during this era

Paleozoic Era 544 million – 245 million years ago Era begins with one supercontinent breaking up into multiple continents Fish, clams, snails, and shellfish developed Early plants and forests grew

Mesozoic Era Also called “Middle Life” 245 million – 65 million years ago Climate warmed, allowing new plants to grow (bananas, palms) Dinosaurs

Mesozoic Era Continued Continental plates collided, creating the Rocky Mountains This era produced veins of gold, silver, copper, lead, zinc, etc. Also produced gems such as Yogo Sapphires

Cenozoic Era Also called “recent life” 65 million years ago – present Era introduces the first mammals and human beings

Cenozoic Era Continued First, Earth became dry and desert-like, then Earth became cool, wet and snowy…creating the Ice Age After the last Ice Age, megafauna either adapted or became extinct. New climate helped new mammals and plants develop