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Science 7
Discovering Science 7
Unit 4
“Earth’s Crust”
Chapter 10
Earth’s Crust Is Made Up Off Rocks And
Mineral.
Minerals vs. Rocks
• Minerals –
A mineral is a pure substance
ex.Gold
• Rocks –
A rock is a mixture of two or more
minerals.
ex. Granite
Mineral/Rock Identification
• Lustre – how light is reflected of the material (Dull, Glassy or
metallic).
• Colour – Spectrum of colour.
• Hardness – Moh’s Hardness Scale (1 softest ex. Talc and 10
hardest ex. Diamond).
• Streak – Residue left after a rock is streak across porcelain
(powder,…)
• Cleavage – Splitting along smooth, flat surfaces called
planes. Ex. Mica
• Fracture – Splitting along rough jagged edges.
Families of Rocks
Igneous, Sedimentary and Metamorphic
Igneous Rock
• Intrusive Rock Formed when molted rock (magma) cools under the
surface of the earth.
ex. Granite
• Extrusive Rock –
Formed when molted rock (lava) cools on the surface of
the earth.
ex. Obsidian
Sedimentary Rock
• Formed when loose particles, weathered
and eroded away, are compacted
together. The extreme pressure and heat
help cement the particles together.
• Cementation – Process by which pieces
of sediments are held together by another
material.
• Layers of sediments form beds.
Sedimentary Rock
Metamorphic Rock
• Metamorphic means “changed form”.
• Formed when extreme pressure and heat,
or hot fluid changes one type of rock into
another.
• The formation of metamorphic rock is a
slow process.
• Parent Rock - The type of rock which has
been changed into metamorphic rock.
Metamorphic Rock
The Rock Cycle
Many Things Are Made From
Minerals and Rocks
•
•
•
•
•
•
•
Zippers
Watches
Shirts
Blood
Muscles
Shoes
Detergents
Mineral and Rock Resources
• Petroleum and Coal – made from the remains of
once living things.
• Metals – Copper, Zinc, Nickel, iron, …
• Gems – Sapphires, Diamonds, emerald, Amethyst, …
Chapter 11
Earth’s Crust Is Constantly Changing.
The Layers of the Earth
The Earth’s Moving Crust
Alfred Wegener (1880-1930)
• Paleogeographic Evidence – Shape of
Continent
- Pangaea
- Theory of Continental Drift
• Biological Evidence – Fossils
• Geological Evidence – Rocks and Rock Layer
• Meteorological Evidence – Climate Change
Wegner’s Theory Rejected
What caused the plates
to move?
Without an answer,
some scientist rejected
his theories.
Today we accept the
explanation of convection
currents
Evidence From The Sea Floor
• Sonar (Sound Waves)
• Magnetometers (Magnetic Fields)
• Deep Sea Drilling (Core Samples)
Types of Plate Boundaries
• Divergent Boundaries
– Pulling apart
• Convergent Boundaries
– Pushing together
• Transform Boundaries
– Sliding past (J. Tuzo Wilson)
Convection Currents
• The driving force that possible causes
plates tectonics (movement of the earth’s
crust).
* The creation of subduction zones – The
area of the crust when one plate is push
below another plate.
Earth’s Crust Catastrophe’s
Earthquakes
- Seismograph (Seismic Waves)
- Bedrock
- Richter Scale
- Focus and Epicentre
Volcanoes
Occur:
- areas where plates converge
- areas where plates diverge
- areas where plates are thin (hotspots)
Mountain Building
• Fold Mountains
• Fault Block Mountains
• Volcanic Eruption
The Geological Time Scale
The Fossil Record – The Origin of Man
“Evolution vs. Creation”
Precambrian – formation of the Earth and
appearance of simple life forms.
Paleozoic – appearance of more complex life
forms .
Mesozoic – appearance and extinction of
dinosaurs.
Cenozoic – appearance of humans.
Chapter 12
Soil Is The Living Component Of Earth’s
Crust.
Weathering
Weathering is the mechanical and/or chemical
breakdown of rocks.
• Chemical
- Acid rain and ground water
-Acid actions of organism (animals and plants)
• Mechanical
– Ice/Frost Wedging
– Plant roots Wedging
– Animal Factor – pathways, burrow, …
Erosion
Erosion is the process that loosens and
moves weathered rock particles over the
earth’s surface.
• Water in motion
• Meteorological processes (rain and wind)
• Geological processes (gravity and glaciers)
Classifying Soil
• Soil is a combination of eroded “rocks and
minerals”, “water”, “air”, and “organic
material.”
• Humas is material made from breaking
down plant And animal remains.
• Texture relates to how soil feels when
robbed between fingers.
- Coarse-textured (sandy, gravel).
- Medium-textured (loamy).
-
ne-textured (clay).
Porosity and Permeability
• Porosity
The amount of empty space in soil or a
rock.
• Permeability
The measure of how easily liquids and
gases pass through a soil or a rock