How has the history of plate movement been captured in residual magnetic fields?
A compass needle points to the magnetic north pole because of the persistent magnetic field caused by the movement of molten metal in the Earth's outer core. As new seafloor is produced at spreading centers, the magnetic minerals (which are naturally occurring in basaltic magma) align with the Earth's magnetic field. As the new rock cools and hardens, the orientation of the Earth's magnetic field at that particular time is frozen and records information like a fossil does. Scientists use this information to measure spreading rates and are able to create detailed charts of the ocean floor dating back about 200 million years.
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The portion of the atmosphere containing the air we breathe is called the
A. troposphere. B. stratosphere. C. biosphere. D. hydrosphere. E. ecosphere.
It is difficult to determine long-term trends in rare events such as extreme heat or extreme cold episodes using graphs such as this because [INSERT FIGURE 3-32. INCLUDE CAPTION]
A) data for rare events is not available prior to 1980 B) rare events might be the result of random variation C) rare weather events are usually caused by earthquakes rather than atmospheric activity D) rare events must be averaged over 25-year periods
Alluvial fan sediment is deposited by flashflood, sheetflow, mudflow, and debris flow
Indicate whether the statement is true or false
The so-called Tornado Belt, or Tornado Alley, of the United States is located ____
A) in Florida B) in the Central Plains C) in the middle Atlantic states D) along the Gulf Coast