Download Earth Science: Tectonic Plates Section 1-1

September 18, 2014
Earth Science:
Tectonic Plates
Section 1-1: Essential Questions
1) What does a geologist do?
2) How were scientist able to study the inside
of the Earth since they were not able to
explore it first hand?
3) Describe the differences between the
lithosphere and asthenosphere.
4) What are the different characteristics of the
Earth's crust?
September 18, 2014
1) Geologist study the forces that make and
shape Earth. They study the chemical and
physical characteristics of rock. Map where
rocks are found and describe landforms. And
study how structures have been shaped
(changed) by the environment.
2) Geologist studied seismic waves produced
by earthquakes to learn about the Earth's
interior. They discover there were 3 main
sections crust, mantle, and core. Seismic
waves travel at different speeds based on the
density of the object they are traveling through.
the more dense the material the faster. Solid
rock is more dense than liquids.
3. Lithosphere primarily makes up the crust,
both continental and oceanic. It is a hard rigid
layer that makes up the surface of the Earth.
Composed of tectonic plates. The
Asthenosphere is the upper portion of the
mantle that is hot flowing magma. It is
responsible for the causing tectonic plates to
move and for the crust to be recycled.
4. Continental crust is made of granite. Is less
dense. Oceanic crust is made of basalt. Is
more dense. Is under oceans.
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Section 1-2: Convection currents and the Mantle
What is heat transfer and describe the three types. Give
examples.
How does density affect convection currents?
What's the role of convection currents in recycling the Earth's
crust?
1) Heat transfer is the movement of energy from a warmer
object to a cooler object. There are 3 types: radiation,
conduction, and convection.
2) Radiation transfer of energy through empty space. Heat
source and object do not touch. Sun warming a pool.
3) Conduction heat transfer through direct contact. Heat
source and object do touch. Child touching hot stove.
4) Convection heat transfer by the movement of heated fluid.
fluids include liquids and gases. Caused by differences in
temp and density. Density is a measure of how much mass is
in an object. As an object's atoms move faster the atoms
spread apart being heated. if they move slower they come
together. being cooled.
5. Convection currents in our Earth. They occur in the
asthenosphere. The heat comes from the Earth's core. it
causes hot columns of mantle to rise slowly. the material
spreads out on the crust and pushes cooler material out of the
way. then the cooler material sinks (subducts) back into the
asthenosphere.
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Section 3: Drifting continents
1) Why was Alfred Wegener's hypothesis rejected by the
scientific community?
2) What evidence did Wegener have to support his
hypothesis?
3) Describe the important scientific discovery Wegener made
in 1910?
1) In 1910 Alfred Wegener made an observation about how
the continents fit together like a jigsaw puzzle. He formed a
hypothesis that all continents were once joined together into
a massive landmass (Pangaea) and has since drifted apart.
The idea of the continents slowly moving over Earth's
surface is known as Continental Drift.
2) Geological structures like mountain ranges provided
evidence of continental drift. Mountain ranges in Africa and
South America and coal mines in Europe and North America
line up.
3) Fossils have also provided evidence. A fossil is any trace of
an ancient organism preserved in rock. Similar plant fossils
have been found in Africa, South America, Australia, India, and
Antarctica.
4) He also found tropical plant fossils on island in the Arctic
and evidence of glaciers in rock that is in a more mild climate.
5) Even though he had all this evidence his theory still was not
supported because he could not provide an explanation for the
force that would push or pull the continents. In the 1960s new
evidence about Earth's structure made scientist rethink
Wegener's Theory.
September 18, 2014
Section 1-4: Sea-Floor Spreading
1) Sonar was used in the mid 1900s to map the ocean's floor.
By bouncing sound waves off underwater structures.
Scientists found a mid-ocean ridge, which formed the longest
mountain range in the world.
2) Ocean floor moves like a conveyor belt, carrying
continents. The mid-ocean ridge is a crack along oceanic
crust. Sea-floor spreading is caused by new molten rock
comes out of the earth and cools and forces the old rock
apart.
3) Evidence of sea-floor spreading. 1. pillow-like rocks: only
fast cooling magma can form these types of rocks. 2. pattern
of magnetized stripes: holds records of reversal in magnetic
field. 3. rock samples: older rocks were further from the ridge
and the younger rocks were closer to the ridge.
4. Ocean floors do not just keep spreading. Instead trenches
are formed by part of the ocean floor sinking (subduction) due
to its high density forming deep-ocean trenches.
5. Due to sea-floor spreading and subduction the oceans
floor is being recycled. The Pacific Ocean is shrinking due to
all the subduction zones and the Atlantic Ocean is getting
larger due to the mid-ocean ridge.
Essential Questions:
1: What causes sea-floor spreading?
2: What evidence supports the idea of divergent boundaries?
3: What process is keeping the Earth from getting bigger and
bigger?