The NAFTA (North American Free Trade Agreement) is the agreement that has lowered trade barriers between Mexico and the rest of North America. It was signed January 1, 1994.
During a volcanic eruption, the geosphere always interacts with the atmosphere, and that is the case with Mount Saint Helen's as well. During the eruption, the volcano which is part of the geosphere, releases lot of gases, ash, debris into the atmosphere. As they are propelled into the atmosphere, these volcanic products became part of the atmosphere, thus affecting its composition and properties, giving us a nice and simple example of interaction between the two spheres.
