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Volcanoes Chapter 3 Section 1 Volcanoes & Plate Tectonics Volcanoes Weak spot in the Earth’s crust Thinning crust allows magma to come up from mantle Magma vs Lava Magma Lava Molten mixture of rock-forming substances, gases, and water from mantle Magma on the surface Cools to solid rock Volcanoes are Constructive Build up land surface Make mountains Make islands Create fertile soil Volcano: Constructive Force! 2 methods of formation 1 Location, Location, Location WHERE ARE MORE “VOLCANIC BELTS”? More under the sea than on land! Micronesia Line up in “belts” Caribbean Plate Ring of Fire: belt of volcanoes around the Pacific Rim Rift Valley, Africa Mediterranean What condition is familiar to Volcanoes? Plate Boundaries! Divergent plate boundaries Mid-ocean ridges Subduction zones (convergent) Surprise! No Subduction Here! “Hot Spots” Far from boundaries or continents’ subduction Magma deep in mantle melts through the crust like a blow torch Surprise! No Subduction Here! “Hot Spots” Can form under continental land Yellowstone National Park, Wyoming Island Arc String of islands formed by volcanoes at a subduction zone & deep ocean trench Island Arc Less dense magma (hot, oozing up) Forms volcanoes in the ocean floor Build up to be islands The making of a volcano: Vocabulary Volcano Magma Lava Ring of Fire Review Island arc Hot spot Mapping Earthquakes & Volcanoes How are volcanoes “constructive”?
