How do terranes relate the growth of continental crust over geologic time? What region of North America illustrates this process well?
What will be an ideal response?
Answer: Terranes are relatively small crustal fragments (microcontinents, volcanic island arcs, or oceanic plateaus). Terranes may be accreted to continents when subduction brings them to a trench, but they usually do not subduct due to their relatively low density. The terranes are "peeled off" the subducted slab and thrust onto the leading edge of the continent. Thus, they add bulk (mass, volume) to the edge of the continent. The western Cordillera is composed of many accreted terranes that originated mostly far to the south. Tectonic motions slathered them on to the edge of North America, and so their deformed, metamorphosed bulk piles up on the continent's leading edge like smashed bugs on the windshield of a fast-moving car.
You might also like to view...
A connected loop of deep and shallow ocean currents transports warm and cool water to various parts of the earth
Indicate whether the statement is true or false
The planet Earth loses heat mainly by
A) conduction. B) convection. C) radiation. D) all of the above
At divergent plate boundaries, plates are moving ____________________. At these locations, new
____________________ forms. Fill in the blank(s) with the appropriate word(s).
Between 1982 to 2007, there was actually a decrease in soil erosion on U.S. cropland
Indicate whether the statement is true or false