Download Introduction to Planet Earth

Tuesday, January 17
Unscramble the following words
for your science starter today:
Can you unscramble all the words below?
Hint: They all start with the letter D.
E D C M O P S E O R 1. I’m called nature’s recycler.
ATDA
2. I can help you make a decision.
SIDSLOEV
3. This happens in a solution.
GAMRIDA
4. You might label me.
EDCBEISL
5. How loud can you be?
The answers are …
DECOMPOSER
1. I’m called nature’s recycler.
DATA
2. I can help you make a decision.
DISSOLVE
3. This happens in a solution.
DIAGRAM
4. You might label me.
DECIBELS
5. How loud can you be?
Introduction to Planet Earth
Let’s dig a hole to China!
Earth Stats
• The Earth's mass is about 5.98 x 1024 kg.
• Earth is the densest planet in our Solar
System (mass/volume).
• Earth is made of several layers with
different compositions and physical
properties, like temperature, density, and
the ability to flow.
The Composition of
the Earth
The Composition of
the Earth
Crust
•Thinnest layer (5-100 km)
•Two types of crust
•Continental
•Like granite
•Average 30 km
•Oceanic
•Like basalt
(Basalt is denser than granite!)
•Average 5-8 km
The Composition of
the Earth
Mantle
•Extremely Thick! (2,900 km)
•It is too far down to drill
•How do we know what it is
made of?
•Scientists infer based on:
•Pushed up rock
•Ocean floor/molten rock
•What is it like?
•Like the mineral olivine
•Large amounts of iron
and magnesium
www.soc.soton.ac.uk
The Composition of
the Earth
N
Core
•Pretty darn big. (6,856 km)
•(Slightly bigger than Mars!)
•33% mass of the Earth
•Scientists think….
•Made mostly of iron
•Some nickel, sulfur, oxygen
•What is the evidence?
•The particular way seismic
waves travel
•Earth’s Magnetic field
S
The
Structure
of the
Earth
Lithosphere
Solid
Asthenosphere
Viscous Liquid
Outer Core
Liquid
Mesosphere
Solid
Inner Core
Solid
Lithosphere = ‘rock sphere’
Crust and upper rigid part of Mantle
Asthenosphere = ‘weak sphere’
Lower part of Mantle
How HOT is it?
Convection
• Convection (heat) currents
– carry heat from the hot inner mantle to the
cooler outer mantle.
• The mantle gets warmer with depth
• top of the mantle is ~ 1,600° F (870° C)
• bottom of the mantle is ~4,000-6,700° F
(2,200-3,700° C)
• The mantle contains most of the mass of
the Earth
Let’s Make Models of the Earth!
•
•
•
•
•
Inner Core (yellow) diameter 2 cm (4)
Outer core (orange) diameter 6 cm (4)
Mesosphere (red) diameter 11cm (4)
Asthenosphere (brown) diameter 12cm (2)
Lithosphere (sand)
– -after assembly roll edges of asthenosphere
in glue and then sand (1.5mM thick)
How do scientists know
what makes up the
earth’s interior if we
can’t actually dig a hole
through the earth to see
it directly?
1.Direct evidence from rock
samples.
and
2.Indirect evidence from seismic
waves when we have an
earthquake. (The speed of seismic
waves and the path they take through
the earth reveal the structure of the
planet.)
Why does the earth
have high temperatures
in the center? Where
does the heat come
from?
The high temps. inside the earth
are the result of heat left over
from the formation of the planet.
Also, radioactive substances
inside the earth release energy.
What kind of rock
makes up the oceanic
crust?
Basalt
A dark rock with a
smooth texture.
What kind of rock
forms the continents?
Granite
A rock that is light in
color and has a
coarse texture.
3 Types of Heat Transfer
1. Radiation--through space, no direct
contact. Ex: Sunlight to earth, campfire
2. Conduction--between materials that are
touching. Spoon gets hot as it sits in a pot
of hot soup.
3. Convection--movement of fluids and
currents in the fluids. Ex: boiling water
Convection
Caused by:
• temperature differences
• density differences
• gravity
Occur in the outer core (magnetism)and
mantle (plate tectonics)
Alfred Wegener 1915
German man who proposed the
Continental Drift Theory.
Pangaea--super continent “all lands”
Evidence:
1. land features
2. fossils
3. climate change
Sea-floor Spreading
The sea floor spreads apart along both
sides of a mid-ocean ridge (forms a crack
in the ocean floor) as new crust is added.
As a result, the ocean floors move like
conveyor belts, carrying the continents
along with them. Molten material fills in the
crack as it rises to the surface. As it cools,
it forms a strip of rock in the center of the
ridge.
Evidence of Sea-floor
Spreading
Read pages 24 F-29 F
Rocks shaped like squeezed toothpaste
Magnetic Stripes
Drilling Samples
Subduction at Trenches
• Where the oceanic crust bends downward
and sinks back into the mantle
• Pacific Ocean is shrinking!!
• Subduction is occurring faster than new
crust is being produced.
Plate Tectonics
The lithosphere is broken into separate
sections called PLATES that move
because of convection currents in the
mantle.
This is the sea-floor spreading and
continental drift theories wrapped into one.
Plate Boundaries--Faults
Divergent--where two plates move apart, at
mid-ocean ridges where sea-floor
spreading occurs.
Convergent--where two plates come
together and collide. The density
determines which sinks. Creates
Mountain ranges.
Transform--slipping past each other.
Earthquakes occur here.