What is the subducting plate involved in the formation of the volcanoes of Central America?

Early in the story when tom finds an indian skull in the woods which he kicks in temper. the devil then makes his appearance and, as tom surveys him, he notices that the devil is neither "negro" nor "indian." in fact, he has a "swarthy" complexion and is "begrimed with soot."

Answerstratovolcanoes///near or in the ring of fire;