Wind and ocean currents are caused by convection. Convection is heat transfer by mass motion of a fluid like the water. When the heated fluid is caused to move away from the source of heat, carrying energy. Above a hot surface, convection occurs because hot air expands, rises because it's denser.
The significance of the map was that it showed how New York City was before it became such a busy place. If he could see the geographical features from long ago
