Geologic Time Scale

What is the geologic time scale? Time-line of Earth’s history Breaks down Earth’s history into units of time

Eras are the largest unit of time. Precambrian Paleozoic Mesozoic Cenozoic Eras are divided into smaller parts called periods. Periods are then divided into even smaller parts called epochs.

Era Period Epoch

Precambrian Era Earliest span of time in Earth’s history. No life for a long time and then very simple life appears. Early life influenced by volcanoes and mountain building

Precambrian (cont.) Oldest rock 4 bya Single-celled organisms 3.6 bya Canadian Shield formed 3.6 bya (bya= billion years ago)

Paleozoic Era Took place after Precambrian Era “Age of Fishes”: living organisms only existed in the seas Early invertebrates and amphibians (first animals to live on land) Tropical climates allowed growth of new species Forests of trees developed

Paleozoic Era (cont.) Formation of Appalachian Mountains in eastern Canada Mass extinction at end of era when 80% of marine invertebrates disappeared Cause of extinction is not clear, but may be related to formation of Pangaea

Mesozoic Era Beginning of the break up of Pangaea North American plate collides with Pacific Plate: formation of Coast Range, then Rocky Mountains “Age of Reptiles” Reptiles, small mammals, dinosaurs and small birds

Mesozoic Era (cont.) Warm climate in Canada Creation of coal, oil and gas in western Canada Era ended with mass extinction by asteroid or climate change 50% of all plant and animal species (including dinosaurs) became extinct.

Cenozoic Era The Era we are currently in!!! “Age of Mammals” Mammals, flowering plants Canada experienced an Ice Age with four periods of glacial activity First humans

Cenozoic Era We still have much diversity but could there be a mass extinction to come???

Formation of Canada Let’s draw…