Geologic Eras

Earth’s Birthday The Earth is very old, 4.6 billion years old! Humans have been around for a tiny slice of that time

If the earth’s history was compressed into a 24 hour day… http://www.youtube.com/watch?v=H2_6cqa2cP4

Another cool fact A book with one page for every year of earth’s history would be 145 miles long and take you 17,500 years to read.

The earth can be divided into four main geologic eras The earth can be divided into four main geologic eras. An era is a span of time in the earth’s history where significant geologic events occurred.

The four eras include: Precambrian Paleozoic Mesozoic Cenozoic

Precambrian- “The oldest and longest” Began 4.6 billion years ago and lasted for 4 billion years Accounts for 87% of the earth’s history The Bedrock of Canada was formed Only part of Canada that existed was the Canadian Shield By the end of this era the first complex organisms had appeared (eg bacteria, 4 billion yrs ago, algae, 3 billion yrs ago)

Stromatolites (The oldest known fossils on earth) The section of river near the Champlain Bridge has one of the best known displays of fossil stromatolites in the country – and certainly in any urban area. At low water periods at the end of dry summers and early fall large slabs of sedimentary rock appear along the river to expose the stromatolites and other ancient creatures. More stromatolites are visible in the transitway walls from the pedestrian bridge at the endof Roosevelt Avenue in Westboro.

Palezoic The Paleozoic had two of the most important events in the history of animal life. At its beginning, multicelled animals underwent a dramatic “Explosion” in diversity, and almost all living animals at the time appeared within a few millions of years. At the other end of the Paleozoic, the largest mass extinction in history wiped out approximately 90% of all marine animal species. The causes of both these events are still not fully understood

Paleozoic- “Age of the Fish/Amphibians” Last 345 million years North America was located near the equator Shallow seas covered the now, Interior Plains of Canada Swamps produced coal and natural gas Appalachian mountains were formed Fish, insects first appeared in the beginning of this era and amphibians were found at the end of the era Simple plants appear on land

Mesozoic- “Age of the Dinosaur” Lasted 180 million years Rocky Mountains were formed Seas covered large parts of North America Dinosaurs and other reptiles roamed through huge swamps and forests First swamp plants appear First birds and mammals appear Innuitian mountains are formed Mass Extinction marks the end of the Mesozoic era

fyi Canada was home of the first ever found dinosaur. They called it Albertasaurus because it was found in the badlands of Alberta.

fyi Dinosaurs are not extinct. Technically. Based on features of the skeleton, most people studying dinosaurs consider birds to be dinosaurs. This shocking realization makes even the smallest hummingbird a legitimate dinosaur. So rather than refer to "dinosaurs" and birds as separate groups, it is best to refer to the traditional, extinct animals as "nonavian dinosaurs" and birds as, birds, or "avian dinosaurs.” It is incorrect to say that dinosaurs are extinct, because they have left living descendants in the form of cockatoos, cassowaries, and their pals

fyi The “raptors” (Dromaeosauridae) According to current thinking, birds are hypothesized to have shared a common ancestor with the dromaeosaurs sometime in the Jurassic period; Dromaeosauridae is thus termed the sister group of the clade Aves (which includes all birds).

Cenozoic- “Age of Humans” Current geologic era Ice sheets covered much of North America “Ice Age”=Glaciers Formation of Rocky Mountains continues Human beings develop Mammal forms of life evolve into species we know today

Clip from “Walking with Beasts” BBC Documentary