Which numbered area on this geologic map of North America would contain the oldest rocks exposed at the surface?
A)1,southern Alaska
B)2,continental platform of west-central Canada
C)3,continental shield of eastern Canada
D)4,coastal plain along the Gulf Coast of the U.S.

Question

Which numbered area on this geologic map of North America would contain the oldest rocks exposed at the surface? 
A)1,southern Alaska 
B)2,continental platform of west-central Canada 
C)3,continental shield of eastern Canada 
D)4,coastal plain along the Gulf Coast of the U.S.

Quizplus · Accepted Answer

The oldest rocks are generally found in the continental shields, which are areas of stable, ancient crust that have not undergone tectonic activity for billions of years. Therefore, the continental shield of eastern Canada (area 3) would be the best choice for containing the oldest rocks exposed at the surface.

Which Numbered Area on This Geologic Map of North America