As early as 1911, Alfred Wegener presented ideas about sea floor spreading. California is destined to sink into the ocean. The fluid motion of the asthenosphere is the cause of the Earth's magnetic field. Basalt magma is a more fluid liquid than that of andesite because it contains less silica and is at a higher temperature. The most common rock type erupted above subduction zones is basalt.
Pahoehoe is a Hawaiian term applied to blocky basalt flows.
The port town of St. Pierre, on the Caribbean Island of Martinique, was destroyed by a nuee ardente. Magmas rise from their source region because they are laden with H2O and other dissolved gases. Valley widening primarily occurs by mass wasting. The Earth's lithosphere is broken into how many large, rigid plates. All answers go on the answer sheet.