Viscosity - resistance to flow of a lava determines how easily the gas escapes. The more viscous the lava and the greater the volume of gas trying to escape, the more violent the eruption will be. Viscosity is most affected by temperature and silica content.
Basaltic magma has a low viscosity whereas rhyolitic magma has a high viscosity.
Volcano - a hill or mountain formed by the extrusion of lava or ejection of rock fragments from a vent. Shield volcanoes - broad, gently sloping cones constructed of solidified lava flows. One characteristic surface of a basalt flow is called pahoehoe which has a ropy or billowy surface. Basaltic eruptions are non-explosive . During the 1908's, Kilauea volcano, Hawaii, was especially active.