Transcript Chapter Two Notes

Chapter 2: Canada’s
Physical Landscape
Formation of the Earth
2.1
Formation of the Earth
2.1 Planet Earth
Formation of the Earth’s Interior
• @5 billion years ago, plantesimals
(meterorites,icy comets) collide  heat
released
(Kinetic energy to thermal energy)
• Entire planet melts (still cooling today)
• Gravity sorts
materials by density
– Fe (iron) in center
– All other compounds
towards surface
Earth’s Four Layers
•
•
•
•
Crust
Mantle
Outer Core
Inner Core
Scrat!
The Crust
• Outer layer
• 5-100 km thick
• 2 types of crust
– Oceanic (very dense)
– Continental (less
dense)
The Mantle
• Middle layer
• Very thick layer
The Core
• Made mostly of iron
• 1/3 of the earth’s mass
• Very hot
Earth’s Layers
• How are the earth’s
layers similar to an
egg?
• Shell=crust
• Egg white=mantle
• Yolk=core
The Earth’s Interior
Distance: 6730 km (3963 miles)
What is ‘ Plate Tectonics’?
• From Greek ‘tektonikus’
meaning building or construction
• Plate tectonics refers to the process of
plate formation, movement, and
destruction.
How the Plates Moved….
Tectonic Plates
• Earth’s crust is broken into about 19
pieces
• These plates move on top of the crust.
Geography of the Plates
• 1915 Alfred Wegener
proposes theory of
continental drift.
• Supercontinent Pangaea (‘all-earth’) [225mya].
• Continents ‘broke apart’ and moved into current positions.
Plate
Movement
History
Evidence for Continental Drift?
• Wegner’s evidence
– Fit of continents
– Match of magnetic bands on rocks on either
side of the Mid-Atlantic Ridge
– Fossil plants, animals, rock types / geology
• match on opposite shores
• deposits inconsistent with current geography
Glacial deposits,
including structures
that indicate ice flow
direction are located in
ancient rocks as shown
on the left.
Wegener suggested
that the pattern formed
with continents
together at the south
pole.
Striking Match of Biological Regions
The Theory of Continental
Drift
Matching Mountain Chains
Striking Match of Geologic
Regions
The Mid-Atlantic Ridge…
Mid-Atlantic Ridge ‘In Action’!
Sea Floor Spreading
Bill Nye
Plate Margins: how do we know?
• Marked by volcanic and tectonic activity
• Crustal Processes
– Destruction (subduction)
– Creation (volcanism)
– Alteration / deformation (folding and faulting)
Subduction Zone?
Subduction Zones
• Activity:
– Subduction zone; shallow to deep earthquakes;
volcanism (continental)
• Examples:
– ocean trench (Pacific Ocean by Japan);
explosive volcanic mountains ‘Ring of Fire’
Subduction Zones
How Might the Continents Look in
the Future?