What are the forces that are thought to cause movement of lithospheric plates in plate tectonics? What will be an ideal response?
Thermal convection produces upwelling at divergent plate boundaries and outward flow directly away
from them. This is believed to contribute to the motion of overlying plates in the sense that they are
carried or dragged along by these currents. Heating of the axis of a divergent boundary causes thermal
expansion that elevates the Mid-Ocean Ridge system, thus creating a slope. This slope brings into play
gravitational forces that tend to move the lithospheric plates downslope away from the ridge axis. In
addition, older oceanic lithosphere is thought to be colder, thicker, and hence heavier than younger
lithosphere and thus tends to sink more readily. This can be seen in the ocean-ocean convergent
boundary at the Mariana Trench where the much older western part of the Pacific plate plunges under
the younger Philippine plate
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A potential problem to finding solutions to our environmental problems is that many current problems are not obvious to people on a day-to-day basis, making them seem less pressing than they really are.
Answer the following statement true (T) or false (F)
The early formation of the modern world-system was driven primarily by
A) colonial missionaries. B) racially-motivated Europeans. C) enlightened monarchs. D) European merchant capitalists.
"B" type climates generally occur
A. beneath sinking air. B. along the equator. C. along the Gulf Stream. D. near the poles.
The average length of time a substance remains in a reservoir in a biogeochemical cycle is its
A. residence time. B. half-life. C. influx rate. D. capacity.