Chapter 10


 

Every year approx. 30 00 earthquakes are strong enough to be felt

 

Seismologists:

Scientists who study earthquakes.

 

Earthquake Distribution Map

 

This map is also a possible proof of Pangaea. This is because the earthquake lines are all between the continents those were once together.

 

Plate Tectonics

 

When examining a map of the world, you might notice that Africa, and South America could fit together.

 

In 1915 Alfred Wegener, a German scientist, said this is only possible through Continental Drift.

Alfred Wegner also suggested that all the continents used to be 1 super continent. He called this Pangaea.

J. Tuzo Wilson further researched Alfred’s work and came up with Plate Tectonics.


About Plate Tectonics

 

Plate tectonics, is the theory that helps explain most geologic process.  The theory states:

 

-       The earth is made up of about 20 different plates

-       Most of the plates are made of continent and ocean

-       They move over a weak layer of hot rock, several 100 kilometres below the earth’s surface

-       The reason why these plates move is not 100% known. It is thought that is because of unequal distribution of heat within the earth.

-       This causes Convection Currents to move the plates

 

 

In this picture it shows that the same species lives in a part where Africa and South America were thought to be connected.

 

 

 

In this Picture, you see that the same types of mountains are in the place where it was though that North America and Europe were connected.

 

In this picture you see that there were ice sheets in parts of the world that are extremely hot today. Scientists believe when Pangaea split, the ice sheets slowly melted off, but it took a long time.

A Picture of the layers of the earth, and how convection currents work to move plates.

 

Canada’s Geologic History

 

The earth’s physical landscape it formed majorly by plates moving over each other, under each other, colliding and creating mountains, or trenches, holes, and gaps.

 

Mountains are slowly worn down by wind, rain, running water, and ice. This is called erosion.

 

We can examine Canada’s geologic history by studying landforms, rocks, and fossils.

 

Geologic Time

 

To make geologic time easier to understand, we divided it into eras.

 

Cenozoic:

 

-       Began 66 Million years ago.

-       Ended: Currently Happening

- Ice sheets cover much of North America

-  Continents take their Present shape

- Humans begin to develop

- Age of mammals

- Modern forms of life evolve

 

MORE INFORMATION ABOUT THIS ERA

-       The final changes occurred which gave Canada’s landforms their present shape

-       The continuing collision of the pacific and North American plates formed the Coast Mountains, and other mountain systems such as the Rockies.

-       Much f the world was under an ice age for the last 2 million years.

-       The seas that use to exist in Canada are now the Interior Plains

-       As the glaciers moved the acted like earth moving machines, scraping and gouging the earths surface. The Appalachian Mountains along the eastern coast and the Canadian Shield were rounded by moving ice

-       The last Ice age ended 6000 years ago for most of Canada

-       This era is the age of mammals. The superior organisms are humans.

 

 

Mesozoic:


-       Began: 245 Million years ago.

-       Ended: 66 Million years ago.

-       Formation of rocky mountains began

-       Shallow seas of interior North America at times

-       Age of reptiles

-       First flowering Plants

-       First birds and mammals

 

More Information About this Era

-       Marked the beginning of the break up of Pangaea.

-       At periods of this era seas, and swamps covered most of Central and Western Canada

-        As Pangaea broke up the North American plate moved west and hit the Pacific plate.

-       The caused a lot of magma to rise

-       The magma cooled and created a large mass of granite

-       This mass of granite cooled and formed the Coast Range Mountains

-       The tremendous tectonic force began to fold the earth’s mountains.

-       Evidence of the huge animals that use to live in these areas can be found in Alberta around Red Deer River

-       The end of this era was marked by another mass extinction, more than half of all the plant and animal species including the dinosaurs became extinct.

 

 

Palaeozoic:


-       Began: 570 Million years ago

-       Ended: 245 Million years ago

-       Periods when large parts of north America were covered by shallow seas

-       Appalachians formed

-       Age of amphibians and fish

-       First insects

-       First plants and animals appear on land

 

MORE INFORMATION ABOUT THIS ERA

 

-       Canadian Landforms continued to shape during this era

-       Sediments were moved by rivers and deposited in shallow seas that surrounded the Shield

-       Over millions of years, these sediments composed the sedimentary rock of today

-       Today these rocks form bedrock that is part of every province

-       Geologists believe that Canada was once near the equator, because they found fossils of tropical animals.

-       In this era the first animals and plants were on land

-       The greatest extinction occurred in this era as 80% of the earths ocean life was extinct in that era

 

 

Precambrian:


-       Began: 4600 Million Years ago

-       Ended: 570 Million Years ago

-       Precambrian shields such as Canadian Shield, Brazilian Shield, African Shield, and Australian Shield are formed

-       First single celled organisms

-       First multi celled organisms

 

MORE INFORMATION ABOUT THIS ERA

-       This era lasted for 4 000 000 000 years. Approx. 87% of the earth’s history.

-       Many cycles of mountain building and erosion took place in this era

-       Only part of the Canadian Shield existed in this era.

-       At times peaks of the Canadian Shield were 12 000 m above sea level.

-        The uplifting happened by a lot of pressure caused the earth to buckle in a process called folding.

-       Other processes such as volcanic action and faulting, in which cracks open, also helped build these mountains

-       There are fossils in the shield dating back to the middle of the Precambrian era. These are the remains of material deposited by algae, the first single celled organisms.