Fold mountains are defined as the formation of folding of crustal rocks by compressive forces generated by endogenetic forces coming from within the earth. These are the highest and most extensive mountains of the world and are found in all the continents.
Characteristics of Folded Mountains:
- Fold mountains belong to the group of youngest mountains of the earth.
- The presence of fossils suggests that the sedimentary rocks of these folded mountains were formed after accumulation and consolidation of silts and sediments in a marine environment.
- Fold mountains extend for great lengths whereas their width is considerably small.
- Generally, fold mountains have a concave slope on one side and a convex slope on the other.
- Fold mountains are mostly found along continental margins facing oceans (C-O Convergence).
- Fold mountains are characterized by granite intrusions (formed when magma crystallises and solidifies underground to form intrusions) on a massive scale.
- Recurrent seismicity is a common feature in folded mountain belts.
- High heat flow often finds expression in volcanic activity (Himalayas is an exception, because of C-C convergence).
- These mountains are by far the most widespread and also the most important.
- They also contain rich mineral resources such as tin, copper, gold etc.
- Folded mountain fossils indicate sedimentary rocks formed from deposition and consolidation mainly in oceanic environments due to marine fossils.
- Sediments are found upto greater depths, thousands of metres (more than 12,000 metres).
- Folded mountains extend for greater lengths but their widths are far smaller than their lengths.
- For example, the Himalayas extend from west to east for a length of 2400 km (1500 miles) but their north-south width is only 400 km (250 miles). It means that folded mountains have been formed in long, narrow and shallow seas.
Such water bodies have been termed geosynclines and it has been established that ‘out of geosynclines have come out the mountains’ or ‘geosynclines have been cradles of mountains’. According to P.G. Worcester ‘all great folded mountains stand on the sites of former geosynclines’.
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