Volcanoes – see separate sheet for more information Associated landform (and plate boundary) Diagram Detailed Description Named example and key information Young Fold Mountains Rift Valley Ocean Ridges Deep Sea Trenches Island Arcs Volcanoes – see separate sheet for more information

Volcanoes – see separate sheet for more information Associated landform (and plate boundary) Diagram Detailed Description Named example and key information Young Fold Mountains Rift Valley Ocean Ridges Deep Sea Trenches Island Arcs Volcanoes – see separate sheet for more information Where an area of sea separates two plates, sediments settle on the sea floor in depressions called geosynclines. These sediments gradually become compressed into sedimentary rock. When the two plates move towards each other again, the layers of sedimentary rock on the sea floor become crumpled and folded. Eventually the sedimentary rock appears above sea level as a range of fold mountains. Where the rocks are folded upwards, they are called anticlines. Where the rocks are folded downwards, they are called synclines. Severely folded and faulted rocks are called nappes. A rift valley is a linear-shaped lowland between several highlands or mountain ranges created by the action of a geologic rift or fault. A rift valley is formed on a divergent plate boundary, a crustal extension, a spreading apart of the surface, which is subsequently further deepened by the forces of erosion. As a lithospheric slab is being subducted, the slab melts when the edges reach a depth which is sufficiently hot. Hot, remelted material from the subducting slab rises and leaks into the crust, forming a series of volcanoes. These volcanoes can make a chain of islands called an "island arc". Examples of island arcs are the Japanese islands, the Kuril Islands, and the Aleutian Islands of Alaska