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.
Earthquakes shake and volcanoes erupt. Sections of the crust are on the move. Mountains push up and wear down. These and many other processes contribute to the rock cycle, which makes and changes rocks on or below the Earth's surface.
