Presentation on theme: "Mountain Belts Geology 12 Ms. Pushie Citadel High School."— Presentation transcript:
Mountain Belts Geology 12 Ms. Pushie Citadel High School
The processes that produce mountain belts are called orogenesis. They include: folding –anticlines –synclines thrust faulting metamorphism igneous activity
There are 5 basic kinds of mountains: Dome Fold, Fault-block, Volcanic, and Plateau mountains.
1. Dome Mountains Dome mountains are the result of a great amount of melted rock pushing its way up under the earth without folding or faulting resulting in a rounded dome. As the dome is raised above its surroundings erosion occurs, and as a result of erosion, peaks and valleys are formed.
2. Fold Mountains Fold mountains are formed when two plates collided head on, and their edges crumbled, much the same way as a piece of paper folds when pushed together. Examples of fold mountains include Himalayas in Asia, the Alps in Europe and the Andes in South America
3. Fault-block Mountains These mountains form when faults or cracks in the earth's crush force some materials or blocks of rock up and others down. Instead of the earth folding over, the earth fractures and blocks are stacked. Examples include the Sierra Nevada mountains in North America and the Harz Mountains in Germany.
4. Volcanic Mountains Volcanic Mountains are formed when molten rock, or magma deep within the earth, erupts, and piles upon the surface. Examples of Volcanic Mountains include Mount St. Helens in North America and Mount Pinatubo in the Philippines.
5. Plateau Mountains (Erosion Mountains) These are mountains that are really plateaus that have worn down from erosion. The dictionary describes these as large areas of ‘high levels’ of flat land.
Isostasy and Crustal Uplift The concept of the Earth's crust in gravitational balance or equilibrium is called isostasy. Consider low density crust floating on a denser mantle that flows. When weight is applied to the crust, it subsides. When weight is removed, it rebounds (uplifts). The continental glaciers melted about 10,000 years ago. In this amount of time, the land has been steadily uplifting due to the removal of the weight. In the Hudson Bay region of Canada, as much as 330 m (about 1000 ft) of uplift has occurred. This is a rate of uplift of roughly 3 - 4 cm/year.
Evidence for crustal uplift. Fossil sea shells found in rocks thousands of feet above sea level. Roman temples with clam borings indicating subsidence followed by uplift. Wave-cut platforms (terraces) hundreds of meters above sea level in coastal regions of California.
Note that mountains have deep roots, as determined through seismological and gravity studies. Continental crust averages about 35 km thick. Under some mountain chains, crustal thickness is approximately twice that thickness (about 70 km thick). As erosion lowers mountains by erosion, isostasy raises them up again. These processes operate until the mountain belt reaches "normal" crustal thickness again.
The World's Tallest Mountain At 29,029ft (8,848m) Everest is the highest mountain in the worldEverest Mauna Kea, an inactive volcano on the island of Hawaii is actually taller. Only 13,796 feet of Mauna Kea stands above sea level, however, if you measure it from its base, which is below sea level, it is 33,465 feet.
The eight-thousanders The eight-thousanders are the fourteen mountains on Earth that are higher than 8,000 metres (26,427 feet) measured from sea level. They are all located in the Himalayan and Karakoram in Asia.
The highest mountains of each continent (the Seven Summits): Mount Everest Asia 8,850 mMount Everest Aconcagua South America 6,959 mAconcagua Mount McKinley (Denali) North America 6,194 mMount McKinley Kilimanjaro Africa 5,895 mKilimanjaro Mount Elbrus Europe 5,642 mMount Elbrus Vinson Massif Antarctica 4,897 mVinson Massif Carstensz Pyramid 4,884 (technically in Indonesia)Carstensz Pyramid Mount Kosciuszko 2,228mMount Kosciuszko (The highest point on the Australian landmass ) Australia