Transcript Earth’s History

III. Layers of the Earth
Inner
core
Outer
core
Inner
core
A. Crust
1. The thin topmost layer.
a. 5 km – 40 km thick
b. Coolest layer
2. Two types of crusts
a. Continental
b. oceanic
c. Thickest in Mountainous regions and thinnest
in oceanic regions.
B. Mantle
1. It is about 2,900 km
(1,800 miles) thick
2. Makes up nearly 80 % of the Earth's total volume
and 68% of its mass.
3. The mantle rock is so hot that it is often partially
molten.
a. 1,600- 3,200oC
C. Outer Core
1.
2.
The outer core is so
hot that the metal is
always molten.
Temperature range
is 3,200 – 4,000oC
D. Inner Core
1.
2.
3.
4.
The hottest of all the layers.
a. Temperature range is
4,000 –4,500oC
The inner core is solid iron
and nickel.
Pressures are so great that it
cannot melt, even though
temperatures are so hot.
The most dense layer
E. Lithosphere
Includes the crust
and the upper mantle.
2. It is cool and rigid.
1.
Lithosphere
F. Asthenosphere
Hot and semi-liquid
2. Consists of the
portions below the
lithosphere.
3. Convection of the
molten rock occurs
here.
1.
IV. Plate Tectonics
1.
Theory of Continental Drift – A theory
developed by Alfred Wegener, a German
Meteorologist, who theorized the world’s
landmasses had once been joined in a giant
super continent called
PANGAEA
A.PANGEA
Permian
Triassic Era
225 mya
220 mya
Cretaceous
period
Jurasic Era
135 mya
65 mya
Present
1. Fossil Evidence Supporting
Continental Drift
2. Rock Evidence
3. Evidence from Glaciers
Theory of Continental Drift
4. Plate Tectonic Theory
A.
B.
A theory that says the entire Lithosphere
of the earth is divided in pieces called
plates.
Plates are constantly moving on top the
aesthenosphere.
1. Two types of plates
a. Continental plates
b. Oceanic plates
B. How the theory came to be
Continental drift was hotly debated off and on for decades
following Wegener's death before it was largely
dismissed.
1. Major breakthroughs helped create the plate tectonic
theory.
a. ruggedness and youth of the ocean floor
b. seafloor-spreading hypothesis
c. documentation that the world's earthquake and
volcanic activity is concentrated along oceanic
trenches and submarine mountain ranges.
Evidence of Sea –floor spreading
Evidence from Mapping
Earthquakes and volcanoes
Map of the tectonic plates
C. Plate Types
1. Divergent Plates
Boundaries
a. Two plates moving
apart.
b. Magma moves up to
the surface and
solidifies making
new crust
c. In the oceans, most
often.
2. Convergent Plates
Boundaries
a. Two plates collide.
b. Oceanic plates are
more dense then
continental plates.
c. Forms trenches and
mountains
Subduction Zone - the dense,
leading edge of the oceanic plate
actually pulls the rest of the
plate into the asthenosphere
3. Transform Plate Boundaries
a. Two plates grind past
each other side by
side.
b. This type of boundary
separates the North
American plate from
the Pacific plate long
the San Andreas fault
Boundary Features