p. 442 Plate
Tectonics
This
Dynamic Earth: The Story of Plate Tectonics
Visit
this United States Geologic Survey (USGS) site to read an online booklet all
about plate tectonics. Scroll down and click on historical perspectives to learn
more about the development of the theory of plate tectonics. What basic question
does plate tectonics answer that Wegener’s theory of continental drift couldn’t
answer?
Savage
Earth: The Earth at Work
At
this Public Broadcasting System site you can learn more about the plates that
move about on Earth’s surface. Scroll down to see a map of Earth with the major
tectonic plates outlined in yellow. The map also shows the locations of earthquakes
during the 20th century. Notice that the earthquakes are clustered at the plate
edges. Why are there more earthquakes along the edges of plates in the Pacific
Ocean than in other parts of the world?
Plate
Tectonics
Go to this site to learn more about plate tectonics. You can
view animations of the formation of a mid-ocean ridge, a subduction
zone, and a fault here. This site is supported by the National Air and
Space Administration (NASA) and by the Southern California Integrated
GPS Network. Scroll down and click on the book to open it, then choose
a subject and click on it. For example, if you click on Plate boundaries,
you can learn more about the three types of lithospheric plates. What
type of plate boundary is the Mid-Atlantic Ridge?
p. 450 Earth’s
Ocean Floors
Developing
the Theory
Visit
this USGS site to learn more about ocean floor mapping, magnetic striping and
polar reversals, seafloor spreading and recycling of oceanic crust, and the
concentration of earthquakes. Scroll down and click on magnetic stripes and
isotopic clocks to see a graphic of the changes in magnetic polarity near a
mid-ocean ridge.
The
Geomagnetic Field – Frequently Asked Questions
Go
to this NASA site to find out more about Earth’s magnetic fields. You can find
answers to questions about geomagnetism here. Scroll down to read the questions
and their answers. Do scientists think Earth’s magnetic field is going to reverse
anytime soon?
Bathymetry,
Topography and Relief at NGDC
This
site is sponsored by the National Geophysical Data Center of the National Oceanic
and Atmospheric Administration (NOAA). You can find color images of the topography
of the ocean floor and of the continents here. The site includes data from databases
on coastal relief, coastlines, global relief and elevation, Great Lakes bathymetry,
and many others. Scroll down and click on seafloor topography from satellite
altimetry. Then click on poster – measured and estimated seafloor topography
to see a map of Earth’s seafloors.
Marine
Sediments
At
this site you can learn more about the different kinds of marine sediments.
Marine sediments are classified as terrigenous, meaning derived from land, or
as pelagic. Pelagic sediments may include fine silt and dust as well as particles
of living things that settle out of the ocean water. Which type of sediment
is associated with deep sea regions?
p. 466 Using
GPS to Predict Earthquakes
Global
Positioning System
Visit this site to learn more about the Global Positioning System
(GPS). Scroll down and click on the book to see its table of contents.
Click on Using GPS to measure earthquakes to see how GPS is used by
the Southern California Integrated GPS Network to predict earthquakes.
How does the GPS measure the size of an earthquake?
The
San Andreas Fault
At this USGS site you can learn everything you want to know
about the San Andreas Fault in California. Click on Introduction, then
click on the arrows at the bottom of the page to move forward or backward
within the site. This site contains lots of maps to show the locations
of the San Andreas Fault as well as associated faults.
The
Southern California Integrated GPS Network (SCIGN)
The
SCIGN is an array of GPS stations distributed throughout southern California.
Most of these stations are located in the metropolitan Los Angeles region. The
objective of these stations is to provide coverage to estimate earthquake potential
throughout southern California. Explore this site to see how GPS is used in
predicting earthquakes in California.
