Translations:Adventist Youth Honors Answer Book/Nature/Geology/17/en
d. The different types of mountains
Fold Mountains
The compressional forces in continental collisions may cause the compressed region to thicken, so the upper surface is forced upwards. In order to balance the weight, much of the compressed rock is forced downwards, producing deep "mountain roots". Mountains therefore form downwards as well as upwards. However, in some continental collisions part of one continent may simply override part of the others, crumpling in the process.
Block or Faultblock Mountains
Block mountains are created when large areas are widely broken up by faults creating large vertical displacements. This occurrence is fairly common. The uplifted blocks are block mountains or horsts. The intervening dropped blocks are termed graben: these can be small or form extensive rift valley systems. This form of landscape can be seen in East Africa, the Vosges, the Basin and Range province of Western North America and the Rhine valley.
Dome Mountains
In geology, a dome is a deformational feature consisting of symmetrically-dipping anticlines; their general outline on a geologic map is circular or oval. The strata in a dome are upwarped in the center; if the top of a dome is eroded off, the result will be a series of concentric strata that grow progressively older from the outside-in, with the oldest rocks exposed at the center. Many geologic domes are too large to be appreciated from the surface, and are readily apparent only in maps. Well-known regional structural domes include the Llano Uplift and the Ozark Dome.
