Converging plate boundaries. continent to continent plate boundary converging if you want to be more specific.
to converge means to bring something together, that's how I always remembered. Transform boundaries move side to side, and are the reason for mainly fault lines, such as the San Andreas Fault in California. All plate boundaries do occur at subduction zones.
The Rainforest, because it has a lot of rain and is a very wet and humid climate which cause more types of vegetation to grow.
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In case of drastic emergency or fallout if the us were to stand alone it would need supplies it could get on its own