Less than 20 percent of Earth's magma extruded through volcanism occurs at oceanic spreading centers. Group startsTrue or False

About 80 percent of the magma reaching Earth's surface is basaltic, with only about 10 percent andesitic and 10 percent rhyolitic.Group startsTrue or False

Analysis of global sites of magma extrusion found that hot spots, such as Hawaii, represent _________blank of the total magma extrusion.Multiple Choice12%73%15%80%

Decreasing the pressure on hot rock generates most magma. Group startsTrue or False

The variations in the composition of magmas govern whether eruptions are peaceful or explosive.Group startsTrue or False

The diagram below shows the formation of a volcanic arc. This arc was formed as a result of an oceanic plate moving underneath a continental plate in a subduction zone.Image courtesy of USGSVolcanic eruptions result in magma rising from the interior of Earth toward the surface. Lava is magma that reaches the surface of Earth. Magma and lava cool to form solid rocks that contain minerals from deep inside Earth. These rocks include metal ores, which are rocks that contain metallic minerals (such as copper, gold, silver, lead, and zinc).Based on this information, which of the following is most likely to be true? A. The distribution of metallic minerals on Earth cannot be predicted due to the inconsistent formation of these minerals. B. The distribution of metallic minerals on Earth cannot change over time because volcanic activity does not occur any more. C. The distribution of metallic minerals on Earth is uneven and depends on the geologic processes that occurred in the past. D. The distribution of metallic minerals on Earth is evenly spread across all continents because geologic processes occur uniformly.