Inner Core : solid, dense, 6,000 º C, Iron and Nickel
Outer Core : Liquid, dense, 3,700º-5,500ºC (increases with depth), Iron and Nickel
Mantle : Solid, minerals rich in Fe, Si, Ma, 1,500º - 3,200º C
Crust : upper layer, rigid, lighter rock, <1,000ºC
The Earth’s Interior
Some terms to know:
Asthenosphere : Upper layer of the mantle, may act in a semi-fluid (plastic) manner
Moho (Mohorovicic Discontinuity): The boundary between the mantle and the crust
Lithosphere : Consists of the crust and the rigid upper mantle
The Earth’s Interior
Where is the crust thickest?
Where is the crust thinnest?
The Ocean Floor.
The Earth’s Interior
Why is the core so hot?
Still retains heat from original formation.
Radioactive materials releasing energy as they decay.
Increased pressure from above.
The Earth’s Interior
What happens to rock density, going from the crust to the core?
What happens to temperature, going from the crust to the core?
What happens to pressure, going from the crust to the core?
Continental Drift and the Origin of Plate Tectonics
Wegener’s Map showing the breakup of Pangea See Reference Table Page 9
Note how they fit together
I.The Theory of Plate Tectonics :
The Earth’s lithosphere is made of a number of solid pieces, called __________ which move in relation to each other.
These plates are “riding”on a more “plastic molten” layer below These plates are “riding”on a more “plastic molten” layer below
This plastic molten layer of magma is called the: asthenosphere
1. Theory of Continental Drift
Proposed by _______ ________ in 1915. It stated that the earth’s continents separated and collided as they have moved over the surface of the Earth for millions of years.
Alfred Wegener (1880-1930) Geographer and Polar Explorer
B. Wegener’s evidence for his
1. When you line up __________
they fit like a puzzle.
2. __________ species have been found on widely separated parts of the earth. Fossil
3. Permian fossils are very similar in widely separated continents
3. _____________ and ______________ have a good match of ancient continental rocks and tectonic _________ and _________ structures. S. America Africa fault fold
4. Some mountain chains appear to be continuous from ____________ to______________ continent continent
5. Evidence of _________ climates different from present. ancient Ex . Finding coal beds which indicate tropical climates
Technology developed during WWII
Sonar - image the deep ocean using reflected sound.
Magnetometer - detect faint magnetic fields.
Developed to search for U-boats
World War II Submarine warfare
Geologist at Princeton U.
1962 publishes “geopoetry.”
Sea floor spreading hypothesis.
Suggested that the ocean floor itself might be moving.
Cold War Nuclear Submarines
1st nuclear powered submarine
6 . Rocks of the ocean basins are _________ than continental rocks. younger
II. Ocean Floor Spreading:
Further evidence of horizontal movement of earth’s crust:
A. The ocean floor has a system of submerged mountain ranges called ______________________
Material from deep within the earth comes to the surface at the ___________________ where it spreads apart to make ________________. Ocean ridges New ocean crust
Sea floor spreading
B. The two major pieces of evidence are: Age of igneous ocean material 1. 2. Reversal of magnetic polarity
When rock hardened it kept the alignment forming a permanent record of the ___________________ of the earth at that time. Magnetic field
N S Magnetic polarity reversal
Rocks found farther from the ridges have a _____________ magnetic polarity. Parallel stripes of ________________ on either side of these ridges preserve the record of many ____________ of the earth’s magnetic field. reversed magnetism reversals
Measuring the Age of the Ocean Floor
1968, establishment of the Deep Sea Drilling Project (DSDP).
Specially outfitted ship for drilling into the ocean floor and retrieving rock samples.
Sediment layers and igneous rock dated to reveal the age of the ocean floor in different places.
Deep Sea Drilling Project ship - Glomar Challenger
C. The _______ _________ (basaltic) igneous rocks of the crust near the ocean ridges are covered with a thin layer of ____________. dark dense sediment
This is evidence that the earth’s crust is very ___________ near the ridges. young
The oldest parts of the ocean crust are found far from the ___________ ridges and near the _______________ ocean continents
Acceptance of Sea Floor Spreading (Plate Tectonics)
1970’s - rapid confirmation of remaining predictions and acceptance of the basic theory by most geologists.
1980’s - Plate Tectonics becomes the dominant paradigm in geology.
1990’s - Development of a detailed plate tectonic history of the last 700 million years.
Lithospheric Plates ___________ in size and are made up of a combination of ___________ crust and ______________ crust vary oceanic continental
Three kinds of plate motion occur at plate boundaries:
convergent divergent transform
Aerial view of the San Andreas fault slicing through the Carrizo Plain in the Temblor Range east of the city of San Luis Obispo. (Photograph by Robert E. Wallace, USGS.)
1a.When ocean collides with continent the_________ ocean plate dives down under or ____________ into the mantle forming a
denser subducts Subduction zone
Oceanic-Continental Convergence Ex. Andes in S.America
1b.When two ocean plates converge the _______ ___________ocean plate will __________ forming an ____________ ________ older subduct island arc denser
Oceanic-Oceanic Convergence Ex. Indonesia, Phillippines,Japan & Aleutians
Continent-Oceanic Crust Collision
1c.When two continental plates converge the edges of _______ are crumpled up forming _________ ________________ both mountains folded
Continental-Continental Convergence Ex. Himalayas
2.At ____________ plate boundaries, the plates move ___________ and ________ flows up forming parallel ridges made of _______ __________ __________ divergent magma new igneous apart rock
Divergent Plate Boundary Ex. Mid-Atlantic Ridge
Iceland has a divergent plate boundary running through its middle
Iceland: An example of continental rifting
3. At ____________ plate boundaries, the plates move ________ each other causing shallow _____________ _______________ transform earth past quakes
Transform Plate Boundary Ex. San Andreas Fault of California
core III. MANTLE CONVECTION CELLS:
These plates are “riding”on a more “plastic molten” layer below III. MANTLE CONVECTION CELLS:
The evidence shows that approximately _______ million years ago, the major continents were _______________ 200 connected
And since that time they have been __ _________ separating
A convection cell is a stream of heated material that is moving because of _________ DENSITY DIFFERENCES
These convection cells exist in part of the mantle called the _______________ ASTHENOSPHERE
The two sources of this heat are: 1. 2. Residual (leftover) heat from the formation of the Earth Heat generated from radioactive decay from the core of the earth
Places on the Earth’s surface where plumes of __________ are rising up from the mantle not located along ________ _________ ________
magma active Plate boundaries
As a plate passes over a hot spot, a _______________ _______________ forms CHAIN OF VOLCANIC MOUNTAINS
The tectonic plate moves over a fixed hotspot forming a chain of volcanoes. The volcanoes get younger from one end to the other.
The only mountain that _______ ________ is the mountain located directly over the _____ ______ remains active hot spot