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