Post on 24-Feb-2016
description
DO NOW Grab a textbook, turn in progress reports if
you have them
Why do we have a magnetic field around our planet?
What does the lithosphere float on top of?
What is the difference between the outter core and the inner core?
OBJECTIVE SWBAT- describe the theory of continental
drift and plate tectonics
Identify the 7 major plates and the 7 minor plates
Identify the three plate boundaries and what feature is associated with each plate boundary
TESTING PLATE TECTONICS
Sections 9.4 and 9.5
GUIDED NOTES Your task- Use your textbooks to fill out the
first column of the guided notes
233
EARTH’S STRUCTURE
Earth’s interior consists of three major zones defined by its chemical composition:1. Crust2. Mantle3. Core
CRUST 1. Thin, rocky outer layer of Earth 2 types: continental and oceanic
Continental crust is about 5-47 miles (very thick) Consists of many rock types
Oceanic crust is about 4 miles thick (thin) Composed of igneous rocks
MANTLE1. Solid, rocky shell that extends to a depth of
about 1800 miles2. Divided into Upper Mantle& Lower Mantle3. Largest layer of the Earth
CORE1. Made mostly of iron-nickel alloy2. Very hot3. Inner core
Radius of about 760 miles Due to the extreme pressure, the material is
solidOuter core
Liquid layer is about 1400 miles thick Earth’s magnetic field is generated from the flow
of metallic iron
LITHOSPHERECrust and upper most part of the mantleRigidASTHENOSPHERE• Beneath lithosphere• Soft and flexible
CONTINENTAL DRIFT HYPOTHESIS A German scientist and meteorologist,
Alfred Wegener, proposed a hypotheses: Pangaea : The continents had once been joined
to form a single supercontinent, Pangaea meaning all land
EVIDENCE FOR CONTINENTAL DRIFT The Continental Puzzle
Similar coastlines on opposite sides of the ocean Continents fit together, like a puzzle
Matching Fossils Fossil organisms found on different landmasses
Rock Types and Structures Several mountain belts end at one coastline and
reappear on a landmass across the ocean○ Appalachian Mountains in US, ending off the coast of
Newfoundland (Figure 4 on page 251) Ancient Climates
Glacier evidence, Figure 5 on page 252
MATCHING MOUNTAIN RANGES
GLACIER EVIDENCE
A NEW THEORY EMERGES… Wegener could not provide an explanation of exactly
what made the continents move Data on earthquake activity and Earth’s magnetic field
became available By 1968, these findings
led to a new theory,plate tectonics
PLATE TECTONICS THEORY The upper most mantle and crust, behave as a
strong, rigid layer known as the lithosphere Lithosphere is divided into plates, which move and
continually change shape and size (move about 5cm per year)
7 major plates (pages 256-257, Figure 8) The grinding movements of the plates generate
earthquakes, create volcanoes and deform masses of rock into mountains
PLATE BOUNDARIES Convergent
Two plates move together Divergent
Two plates move apart Transform (fault)
Two plates slide past each other
FEATURES ASSOCIATED WITH BOUNDARIES Volcanoes- Subduction zones (convergent
boundaries)
Mountain ranges – (convergent boundaries)
Sea floor spreading – Ocean Ridge (divergent boundaries)
Earthquakes – (transform)
VOLCANO
MOUNTAIN RANGE
SEA FLOOR SPREADING
PLATE TECTONICS http://www.youtube.com/watch?v=
ryrXAGY1dmE
TESTING PLATE TECTONICS Paleomagnetism
When a rock forms, it becomes magnetized in the direction parallel to Earth’s existing magnetic field
Normal polarity – when rocks show the same magnetism as the present magnetic field
Reverse polarity – when rocks show the opposite magnetism as the present magnetic field
EVIDENCE FOR PLATE TECTONICS The discovery of
strips of alternating polarity, which lie as mirror images across ocean ridges, is among the strongest evidence of seafloor spreading
ANIMATION http://earthguide.uc
sd.edu/eoc/teachers/t_tectonics/p_paleomag.html
DIAGRAM Draw a diagram and label 1) sea floor spreading happening at a mid
ocean ridge 2) Subduction happening between oceaninc
and continental crust near a trench 3) A mountain range along a coastline
** Label what type of boundary is associated with each feature (transform, convergent, divergent)
EXIT TICKET
EVIDENCE FOR PLATE TECTONICS Earthquake Patterns
Scientists discovered a close link between earthquake origins and ocean trenches
Earthquakes occur only within the subducted slab of oceanic lithosphere
Ocean Drilling Youngest oceanic crust is at the ridge crest, the oldest crust is at the continental margins Data on the ages of seafloor sediment confirmed the seafloor spreading hypothesis
EVIDENCE FOR PLATE TECTONICS Hot Spot (Volcanic
area) A concentration of
heat in the mantle produces magma, which rises to Earth’s surface creating volcanic mountains
Hot Spot evidence supports the theory that plates move over Earth’s surface
Hawaiian Islands
CAUSES OF PLATE MOTION Convection occurring in the mantle, specifically
asthenosphere, is the driving force for plate movement Convective flow is the motion of matter resulting from
changes in temperature Warm, less dense material rises Cool, more dense material sinks
The unequal distribution of heat within Earth causes convection in the mantle, which drives plate motion
CAUSES OF PLATE MOTION Slab-pull occurs when the cool, dense
oceanic crust sinks into the mantle and “pulls” the lithosphere along
Ridge-push causes oceanic lithosphere to slide down the sides of the oceanic ridge under the pull of gravity
EARTHQUAKESEarthquakes: The
shaking of the earth’s crust caused by the release of energy.
A. focus: point within Earth where the EQ begins
B. epicenter: location on earth’s surface directly above focus
C. faults: 1 cause of EQ’s, large fracture in crust
CAUSES OF EARTHQUAKES