Canada
UNIT 2: Physical diversity
Chapter 4:
Geologic History
Geological History
• Our physical appearance has changed over time.
• Land is being built up. HOW?
• Volcanoes
• Moving plates
• Deposition
• Land being worn away. HOW? (Erosion)
• Rain, rivers and oceans
• Wind
• Glaciers
Ex. Ancient seas have disappeared.
Mountains that were once high are now worn flat.
Pages 26-27
Geologic History
• Many years ago Canada’s landscape looked
very different from how it looks today.
• Two forces have mainly changed the physical
landscape.
– Erosion and Mountain building.
• One being stronger than the other….
Q.
How have things changed over time?
Geologic History
Geologic time: history of how the earth has
changed from its formation to the present.
• Earth is approx. 4.6 billion years old.
• Earth’s geologic history can be divided into
4 eras (time periods).
– Cenozoic
– Mesozoic
– Paleozoic
– Precambrian
Geologic History
• Each era represents a time of major
sediment deposition and earth movement.
• In other words, significant building up,
wearing down and movement of the land.
Precambrian Era
– Refers to “earliest life” and is the oldest!!!
– 4.6 billion to 600 million years ago.
– Lasted over 4 billion years.
– Many cycles of building and wearing down
(EROSION).
– Our continent and in particular, the Canadian
Shield was formed during this era.
– Primitive life forms such as single-celled
plants and animals.
– Pages 28 - 29
The Canadian Shield
Paleozoic Era
• refers to “ancient life”
• 600 to 225 million years ago (lasted 375
million years).
• More mountain building, but lots of erosion of
the Canadian Shield as well.
• Erosion produced sediments which are small
particle of rock that have been worn down.
• These sediments were moved about by rivers
and deposited elsewhere.
Paleozoic Era
• Layers of sediments were compressed together
to form sedimentary rock.
• They have become the bedrock (underlying
solid rock beneath the layer of soil) in every
province.
• Appalachian mountains in Eastern Canada
formed (p. 30) when these layers of
sedimentary rock were forced UPWARDS.↑
The Appalachians
Formation of the Appalachians
Mesozoic
• Refers to the “Middle life.”
• 225 to 70 million years ago
• Innuitian mountains formed when
eastern Arctic “FOLDED”
• Rocky Mountains in Western Canada
started to form (at the end).
Mesozoic – Formation of fuel deposits
(page 31-top)
• Warm climate
• =
• swamps and forests
• =
• Dead trees & Vegetation
• =
• Swamps, sand & silt
• =
• Compressed layers
• =
• Coal, oil and gas deposits formed
Cenozoic
• Refers to “recent life.”
• 70 million years ago to now (has not ended).
• More mountain building through folding,
volcanoes and faulting.
• Glaciers were the most significant force in
shaping the land during this era and
especially Canada as we know it today!!
• They eroded and rounded the Canadian
Shield and Appalachian Mountains.
Cenozoic
• Once melted, they deposited the eroded
material to create the lowlands surrounding
the Canadian Shield.
• Some are still present today in Canada.
• Age of mammals (including humans!)
• Great Lakes - St. Lawrence Lowlands
• Hudson Bay - Arctic Lowlands
• Interior Plains
Questions - Review
Page 32
• #1 = ( 1 Pt)
• #2a = (2 Pts)
• #2b = ( 3 Pts)
• #3a = ( 1 Pt)
• #4a = ( 1 Pt)
• #4b = ( 1 Pt)
• #4c = ( 1 Pt)
• #4d = ( 1 Pt)
•
•
•
•
•
•
•
•
Page 32
#5b = ( 1 Pt)
#6a = ( 1 Pt)
#6b = ( 1 Pt)
#7a = ( 1 Pt)
#7b = ( 1 Pt)
#7c = ( 1 Pt)
#7d = ( 1 Pt)