GEOG 1120 Lecture Notes - Lecture 8: Volcanic Glass, Mafic, Mount Vesuvius
Document Summary
Igneous processes at the surface are extremely hazardous. Viscosity of fluid => resistance to flow. Viscosity of lava controlled by three factors: chemistry of lava, temperature of lava, gas content of lava. The more silica it have, the thicker it will be and the less runny it will be. The higher the temperature, the lower the viscosity. The lower the temperature, the higher the viscosity. The lower the gas, the higher the viscosity (air has low viscosity). Viscosity of lava controls the behavior and features of lava: pahoehoe lava. => smooth rope-like features of very runny lava. => flow consist of thousands of small units of lava flow called toes: aa lava. => lava flow tend to be thicker than the pahoehoe lava. => rounded bulbous/pillow shaped features of cobbled runny lava. => cools in water and creates it"s shape (hot lava flows into the water and cools rapidly, creating it"s pillow-shaped structure).
