Discuss the geothermal gradient. What is it? What causes it? What are its limitations?
Temperature increase with depth, or geothermal gradient, is approximately 25C/km near the surface. In areas of active or recently active volcanism, the geothermal gradient is greater than in adjacent nonvolcanic areas, and temperature rises faster beneath spreading ridges than elsewhere beneath the seafloor. Much of Earth's internal heat is generated by radioactive decay. When isotopes decay, they emit energetic particles and gamma rays that heat surrounding rocks. Because rock is such a poor conductor of heat, it takes little radioactive decay to build up considerable heat, given enough time. Unfortunately, the geothermal gradient is not useful for estimating temperatures at great depth. But if various studies and hypotheses are reasonably accurate, the geothermal gradient in the mantle is only about 1C/km.
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Ice cores record both the record of past temperatures, and also the causes of climate change
a. true b. false
Which district in the North American Manufacturing Belt has a number of its cities located along the Erie Canal?
A) the central New York and Mohawk River valley B) Western Great Lakes, running from Detroit to Chicago C) Pittsburgh-Cleveland-Erie D) Middle Atlantic, including metropolitan New York E) southern New England, especially Boston
Which two uses consume most freshwater in the United States?
A. irrigation and drinking water B. mining and industrial use C. mining and raising livestock D. drinking water and showering E. thermoelectric power and irrigation
Instead of the vertical displacement of other faults, a ________ fault has horizontal displacement between the two sides
A) strike-slip B) reverse C) overthrust D) graben E) normal