GEOLOGY

Detailed explanation-1: -Viscosity depends on primarily on the composition of the magma, and temperature. Higher SiO2 (silica) content magmas have higher viscosity than lower SiO2 content magmas (viscosity increases with increasing SiO2 concentration in the magma).

Detailed explanation-2: -The amount of silica in magma helps to determine its viscosity. The more silica magma contains, the higher its viscosity. Magma that is high in silica produces light-colored lava that is too sticky to flow very far; ex. Rhyolite.

Detailed explanation-3: -A magma’s viscosity is largely controlled by its temperature, composition, and gas content (see downloadable programs at the bottom of this page). The effect of temperature on viscosity is intuitive. Like most liquids, the higher the temperature, the more fluid a substance becomes, thus lowering its viscosity.

Detailed explanation-4: -A magma’s silica content will not only control the rock type that forms, it also controls the relative viscosity of the magma. Differences in a magma’s viscosity will determine the shape a volcano takes. High-silica (basalt) magma has a much lower viscosity. It flows much easier and over longer distances.

Detailed explanation-5: -What 2 factors determine the viscosity of magma? It depends upon its silica content and temperature.