Island arc: Magma from creates volcanoes that form arcs of Earth’s crust islands in the ocean. Mid-ocean ridge: a string of underwater mountains, with a deep valley running along its crest. Rocks of the ocean floor are very young near it. Mountain building: buckles, folds, and thickens, pushing up Earth’s crust mountains. Coastal volcanoes: Magma from mantle rises to surface and layer upon Earth’s layer forms volcanoes along a coast.
Island arc: Magma from Earth’s crust creates volcanoes that form arcs of islands in the ocean. Mid-ocean ridge: a string of underwater mountains, with a deep valley running along its crest. Rocks of the ocean floor are very young near it. Mountain building: Earth’s crust buckles, folds, and thickens, pushing up mountains. Coastal volcanoes: Magma from Earth’s mantle rises to surface and layer upon layer forms volcanoes along a coast.