Question
22
The map below shows the approximate ages of rocks found in the lithosphere of different regions of North America.
< 1.5 bilion
between 1.5 and 25
> 25 bilion
Modified from image courtesy of NPS
What does this image demonstrate about the North American continent?
O A. Tectonic process have caused the continent to grow over time.
O B. The edges of the continent formed before the center formed.
O C. The North American plate has been subducted beneath other tectonic plates.
D. Destructive processes have caused much of the continent to disappear.
Answer
The image demonstrates the age distribution of rocks in the lithosphere of different regions of North America. It does not provide information about tectonic processes causing the continent to grow or disappear, or about subduction of the North American plate. Therefore, options A, C, and D are not correct. Option B is also not entirely accurate as the map does not show the exact sequence of formation of different regions of the continent. However, it can be inferred that the rocks in the edges of the continent are generally older than those in the center, which may suggest a pattern of crustal accretion or deformation. Therefore, the most appropriate answer is B.