Transcript Notes Rdg Guide Plate Tectonics Pw Pt 2016

Plate Tectonics
Continental Drift
• Alfred Wegener
• German polar researcher, and
meteorologist.
• hypothesized that the
continents were slowly drifting
around the Earth.
• His hypothesis was
controversial and not widely
accepted until the 1950s,
when numerous discoveries
such as palaeomagnetism
provided strong support for
continental drift, and thereby
a substantial basis for today's
model of Plate tectonics
Pangaea
the super continent
approx. 250,000,000
Evidence:
Shorelines appear to match
(like pieces of a puzzle)
Matching rock types and structures
Evidence:
Matching fossils on different continents
Ancient climates
Large grooves
Carved by glaciers
Are found in
Tropical areas
Large coal fields of N America and Russia were once at the equator
http://www.ucmp.berkeley.edu/geology/tecall
1_4.mov
Rejecting the Hypothesis
No way to explain the mechanism that
would be able to move whole
continents about in the ocean.
After WWII there was a surge
In advanced technology used
To advance scientific research.
Extensive studies of the
Ocean floor revealed
Much about the
Layers of the Earth
Mafic
basalt
Felsic
granite
Plate Tectonics
Major discoveries
In science & technology
Allow scientists to
Develop the Theory
Of Plate Tectonics
The Earth’s surface is divided into large plates
That move about on the “plastic” asthenosphere
What makes the plates move
Radioactivity- Heat energy from decaying
radioactive elements
Uneven heat in the
Mantle causes
CONVECTION CURRENTS
The solid lithosphere is broken into pieces and moves on top of the
“weak” or “plastic” asthenosphere. This movement explains the cause of
earthquakes, volcanoes, oceanic trenches,
mountain range formation, and many other geologic phenomenon.
Types of Plate Boundaries
• Divergent Boundary
Lithospheric plates move apart
Seafloor spreading and
A Mid-Ocean ridge
KEY Words: rift, ridge
Older rock
Older rock
Younger rock
Youngest rock is found near the ridge, oldest rock is near the continents
Locations:
Red Sea
Great African Rift Zone
Mid-Atlantic Ridge
A divergent boundary
Africa’s Great Rift Valley
Can you find it on a map?
Convergent Boundaries
Ocean – Continental Boundary
Locations:
Andes Mt.s
Cascade Mt.s (can you find these on a map?
Key Words:
Subduction
trench
Convergent – oceanic- oceanic
Locations:
Japan
Philippines
Indonesia
Aleutian islands
(Find these on a map)
What is formed “behind”
The string of islands?
Key Words:
Subduction,
Trench
Island arc
Continental – Continental Convergent
Locations:
Himilayas
Alps
(find these on a map)
Note: NO subduction zone,
NO trench. Mt.s are folded
upward.
Transform Plate Boundary
Location:
The San Andreas Fault
(find on a map)
Evidence - Polar Wandering found in the layers of rocks
The following slides show
details of more evidence
gathered to support
Plate Tectonic Theory
Evidence:
Magnetic Reversal
The metallic minerals in
The rocks are a “record”
Of the direction of the poles
At the time of crystalization
http://jeffcoweb.jeffco.k12.co.us/isu/science/9earth/maganimation.html
Evidence:
Seafloor Spreading – each “layer” shows different ages of the rock and demonstrates
When there is a polar reversal.
(Like a horizontal version of a drill core sample of the deep ocean)
Earthquake Patterns
When plotting the locations of earthquakes around the world. . They align with
Plate boundaries. (all have earthquakes, but not all boundaries have volcanoes, only boundaries with a subduction zone)
Ocean Floor Drilling
Hot Spots – unusual concentration of heat in the mantle
Creates so much heat energy it breaks through the lithosphere
In the middle of a plate.
Intraplate Hot Spots:
Hawaiian islands
The plate moves but the hot spot stays in place
Intraplate Hot Spot:
Yellowstone National Park
Unusual Hot Spot on a plate boundary
Review:
Which type of boundary has upward convective movement?
Which type of boundary does downward convective movement occur?
What type of plate boundary is there no destruction of the earth’s lithosphere?