Figure 12.22
Accreted terranes. (A) Pieces of continental crust and volcanic island arcs are carried along on oceanic crust toward a continent. The oceanic crust subducts, forming active volcanoes, but the relatively buoyant terranes do not. Instead, they are scraped off and fused onto the continent’s margin. (B) Through this process many different terranes have been added to the North American landmass at various times in the past.(B photos, from top: Andrew Greene, Hawaii Pacific University; © altrendo nature/Stockbyte/Getty Images; David Lynch)