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Chapter 6
6.1 Notes
Earth’s Structure
6.1 Notes
•
3 compositional layers of Earth
1. Crust – outermost layer of the Earth
– 2 types of crusts:
1. continental (granite) crust
2. oceanic (basalt) crust
2. Mantle – layer of the Earth between the crust and
the outer core
– partially made of magma
3. Core – inner most layer of the Earth
– mainly made of metal iron
6.1 Notes
• What is the difference between oceanic
crust and continental crust?
– Oceanic crust is denser (heavier) than
continental crust
– Ocean water is on top of the oceanic crust
– Oceanic crust is made of basalt
– Continental crust is made of granite
6.1 Notes
•
5 layers for the physical structure of Earth
1. Lithosphere – the layer that is made of the
crust and the upper part of the mantle
– another name for the crust (made of rock)
– made up of tectonic plates that float on the asthenosphere
2. Asthenosphere – a soft layer of the upper part
of the mantle beneath the lithosphere
– The lithosphere and its tectonic plates float on the
asthenosphere (made of magma)
3. Mesosphere – a strong layer of the mantle
beneath the asthenosphere
– Made of solid rock
6.1 Notes
4. Outer Core – the layer of the Earth between the
mantle and the inner core
•
made of liquid iron
5. Inner Core – the layer of the Earth that extends
from the bottom of the outer core to the
center of the Earth
•
made of solid iron
Physical Structure
Chemical Composition
6.1 Notes
• Continental Drift – the theory that continents
can drift apart and have done so in the
past
• Alfred Wegener – created the continental drift theory
• What was the problem with Alfred Wegener’s
theory of continental drift?
– Not enough evidence to prove his theory
Continents Collide
•Eventually when plates
move together the
continental crust collides
•It also pushes and folds
the rocks into high
mountains
•The Himalayas rise to
8848m and are still
growing today
6.1 Notes
•
5 pieces of evidence that proved Alfred
Wegener’s theory of continental drift:
1. Continents looked like they fit together like a
puzzle – super continent “Pangaea”
2. The same fossils (plant and animal fossils) were
found on different continents
3. The same rocks were found on different
continents
4. Mountain ranges on different continents appear to
be once connected
5. Similar glacial deposits were found on different
continents
Fossils Found
6.1 Notes
• Sea-floor spreading – new oceanic crust is
created by magma getting forced upward
by convection currents and separating the
old crust
– Sea-floor spreading
creates mid-ocean
ridges
This is
a midocean
ridge
This is an
example of
sea-floor
spreading