Which part of Earth is primarily responsible for Earth's magnetic field? Why? What are the characteristics of magnetic reversals? How often do they occur? When will the next one occur, and what will happen when it does?
What will be an ideal response?
Earth's magnetism is generated in the liquid outer core. Though the textbook doesn't discuss it, the answer to why is the dynamo theory. The locations of the north and south magnetic poles are surface expressions of Earth's magnetic field. This magnetic field migrates and, at various times in Earth's history, it has faded to zero and then returned to full strength with the polarity reversed. This has happened 9 times during the past 4 million years. The average period is about 500,000, but can range from 20,000 to 50 million years. The last reversal was 790,000 years ago. Based on magnetic decay, we are about 1,000 years from entering the next phase.
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Using Figure 12.25 in your textbook, which of the following is not a normal consequence of an oceanic-oceanic convergent plate boundary?
A) The denser crust subducts the less dense plate. B) Thrust faults lift up above the subduction zone. C) A volcanic island arc forms above where the subducting plate melts. D) A trench forms at the location where subduction begins.
Outline the factors that contribute to the severity of a storm surge. What will be an ideal response?
A tundra climate is situated farther from the poles than a subarctic climate
Indicate whether the statement is true or false
What proportion of food products sold on U.S. supermarket shelves contains some form of genetically engineered crop?
a. 20% b. 30% c. 50% d. 60% e. 70%