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4 Types of Mountains fault-block volcanic upwarped folded Mountain Age Older mountains- not as high; rounded; may have stopped forming Younger mountains- high and rugged; still forming Fault Block Mountains Sierra Nevada in California Teton Range in Wyoming See page 300 Huge blocks of rock are separating from surrounding rock; jagged peaks Rock layers are being pulled from opposite directions and the blocks slide downward. Sierra Nevadas Grand Teton Mountains Folded Mountains Two plates push together and squeeze rock layers which cause rocks to buckle and fold. Appalachian Mountains are an example. North Am. and African plates converged together Appalachian Mountains Upwarped Mountains Southern Rocky Mountains Black Hills in South Dakota Forces inside Earth push up crust The sedimentary rock layers will erode, exposing the igneous or metamorphic rocks underneath. Black Hills Southern Rocky Mountains Volcanic Mountains Washington’s Mount Saint Helens Some volcanic mountains are caused by subduction zones where convergent boundaries form. The oceanic plate sinks under the continental plate. Some volcanic mountains are caused by hot spots (Hawaiian Islands) Mount Saint Helens Hawaiian Islands Volcanoes-- formed from hot spots Other types of uplift Isostasy- the principle that states the Earth’s lithosphere floats on a plasticlike upper part of the mantle, the asthenosphere. As mountains continue to grow they, they sink down deeper into the mantle. As mountains erode, the mountain rises again because the weight has been removed.
