Unit 2 Lesson 3: Geologic History The Four Major Eras

There are four Geologic Eras 1) Precambrian Era 2) Paleozoic Era 3) Mesozoic Era 4) Cenozoic Era

1. Precambrian Era 4600 million to 600 million years ago Canadian Shield was formed (major geological event) Development of primitive life forms in the ocean (major biological event)

Precambrian Era Earth was formed Faulting and Folding-see text Mountain ranges were formed and worn down Areas of lands/oceans developed and disappeared Surface of our continent was formed

2. Paleozoic Era 600 million to 225 million years ago Formation of the Appalachians (major geologic event) First plants and animals on land (major biological event)

Paleozoic Era Erosion gradually wore mountains away Rivers moved the eroded particles into shallow seas These sediments compressed into sedimentary rock

Paleozoic Era End of this era sedimentary rock to the east of the CAN shield was forced upwards to form the Appalachian mountains Amphibians were the 1 st animals to live on land, moved onto land during this era

3. Mesozoic Era 225 million to 70 million years ago Beginning of the formation of the Rocky Mountains (major geological event) Age of the reptiles, first birds and mammals also present (major biological event)

Mesozoic Era The rocks of the eastern artic fold up to form the Innuitian Mountains Seas covered much of central/western CAN (beginning of era) Rocky Mountains start to form

Mesozoic Era Climate warm, huge swamps and forests begin to develop Dinosaurs/reptiles lived in these swamps Plants/creatures in the swamps became covered with sediments and compressed into coal/oil/gas

4. Cenozoic Era 70 million years ago to today Ice covered much of N.A., formation of the Rocky Mountains (major geological event) Creation of humans (major biological event)

Cenozoic Era CAN landform developed it’s current form 4 periods of glacial activity Glacial movement carved out lakes/rivers/hills/plains/swamps across CAN

Cenozoic Era Age of the mammals Change in climate killed off the dinosaurs and mammals became the dominant species