This week we are studying the three processes of Mountain Building. Mountain building is a very slow process that can take many thousands and even millions of years. Over this time many earthquakes will occur, slowing changing the shape of the land to create a mountain in one of three ways:
Folding, creating Folded Mountains
Faulting, creating Fault-Block Mountains
Volcanic Activity – creating a volcano or a dome mountain
Folded mountains are caused by compression stresses and reverse faults, causing a slow uplift of earth’s crust and rocks. These usually occur along plate boundaries where two plates are converging. The process is similar to pushing a carpet lying on a floor up against a wall to form. The Himalayas in Asia, the Alps in Europe, the Andes in South America and the Appalachian Mountains of the US are good examples of Folded Mountains. Interesting national parks would be the Rocky Mountain National Park in Colorado and the Great Smoky Mountains National Parkin Tennessee/North Carolina.Folding of a MountainFault-blockmountains are created where the crust may be stretched apart by tension stresses. Cracks in the Earth’s surface are formed by normal faults, which can result in the formation of fault-blockmountains. If there are two parallel faults, the crustal block between them may either rise to form a fault-block mountain or fall to produce a rift valley. Examples are the Grand Teton National Park in Wyoming and the Great Rift Valley in Africa.Fault-Block Mountain BuildingVolcanic Activity -These mountains form when plate activity allow magma to rise up through the earth’s crust and erupt on the surface. This can create a mountain of lava (magma outside the crust) and ash that can form very tall mountain peaks called volcanoes. The mountain peaks of the Pacific Northwest, such as in Mount Rainier National Park and in North Cascades National Park, as well as Kenai Fjords National Park in Alaska, are examples of volcanic mountains. Volcano BuildingSometimes the magma in the crust simply pushes an area of the crust up into a dome shape. The crust doesn’t snap and break, but rather it swells upward as a bump on the crust’s surface. This is called a Dome Mountain. Examples of these would be Yosemite National Park in California and the Adirondacks of New York.Dome Building
The Formation of a Volcano
