Four ways to make a mountain

There are only four main processes on Earth which produce vertical relief upon the continents.

A volcano erupts. They can produce 10,000 ft of relief on land. In the ocean, the Hawaii volcano is some 37,000 feet tall measured above the flat sea floor. Also, magmas sometimes rise in mushroom shape and force their way in between sediment layers (also shown here) and they may 'bow up' the land above while not breaking the surface. These buried mushroomed volcanic masses are called laccoliths. There are many laccoliths on the Colorado Plateau including the Henry and La Sal Mountains and Navajo Mountain sitting boldy on the south shore of Lake Powell near Rainbow Bridge.

A rift valley may form as the crust is ripped or 'rifted' apart. Note the directional arrows. This is the origin of Basin and Range country. As pull-apart happens, faults break and alternating blocks drop down into hot rock material with the consistency of crunchy peanut butter. Note that with this process nothing is pushed up. In fact the lower portion of the crust is stretched and thinned. More details on this later in the description of Basin and Range. Other rift valleys are famous: The Rhine River valley is a rift valley, as is the valley of Lake Baikal Russia (world's deepest lake), and the east African rift valley where Louis Leakey became famous.

Regional denudation caused by stream erosion always acts on any kind of land of larger area that is uplifted by gigantic huge pushing-up forces from below. Once the land is elevated, erosion by water-ice-wind ALWAYS occurs because the water is given strength by virtue of its gradient back down to the sea. In contrast, the Mississippi River at New Orleans, our biggest river, cuts NOTHING away from its bottom because it is at sea level, though it transports megatons of sand and silt from its places of origin to its growing delta. Its arrangement is static. In the diagram, as seen so well on the Colorado Plateau, stream erosion acts on flat sediment layers of variable hardness to produce canyons, mesas, plateaus, buttes, spires. Just go visit Canyonlands or Capitol Reef or Grand Canyon National Parks, or Monument Valley on the Navajo Reservation that John Ford and Stephen Spielberg loved so much, and imagine how much rock has been removed.

Regional compression - continent-continent collision (like India colliding with Asia) produces spectacular results like the Himalayas or the European Alps. These kinds of mountains float high above sea level because they are buoyed up by having two continental thicknesses beneath them. The guiding principle is ISOSTACY, the floating principle. Float a plank of wood in your bathtub. Note how much is above water. Then add a second plank on top of it. Let it stabilize. The amount of wood above water is now twice as much and the roots are twice as deep. The situation has been isostatically adjusted. Icebergs do the same thing, to rise up as their tops melt.

Section 5. Breakup of Pangea supercontinent

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