Land and Resources, Natural Regions
Doi Inthanon, Indo-Australian plate, south mountains, southwest monsoon, Chao Phraya
Thailand comprises five major natural regions. The first is the country’s heartland: a wide alluvial plain whose fertile soils are replenished by the Chao Phraya and other rivers flowing out of the northern mountains. This central plain has been described as one of the “rice bowls” of Asia because of its high agricultural productivity. The plain was originally a swamp, created by a much older river system that was partially submerged when the sea level rose at the end of the last Ice Age (about 16,000 years ago). The plain is still subject to severe flooding during the wet season of the southwest monsoon (approximately April to September).
Thailand’s second natural region consists of mountain ranges lying north of the central plain. Oriented on a north-south axis, the ranges are formed of granite and limestone. Separating them are valleys, where the first Thai settled between the 9th and the 14th centuries. Thailand’s highest mountain, Doi Inthanon, rises among the northern mountains southwest of the city of Chiang Mai to a height of 2,595 m (8,514 ft). The northern ranges are part of a wider mountain system that was created when sections of the Indo-Australian plate moved north, pressing against the Eurasian continental plate and forcing up the Himalayas and the mountains of Indonesia.
Thailand’s third natural region, which lies to the west along the border with Myanmar, is also marked by north-south trending mountains. These mountains create a natural frontier that is breached at Three Pagodas Pass, which has been a strategic crossing point and defense outpost throughout Thailand’s history.
To the east of the central plain, the Khorat Plateau, an undulating sandstone area that rarely rises above 200 m (660 ft), forms the fourth natural region. Dry and infertile, the plateau is drained by tributaries of the Mekong River.
Lastly, a long peninsula—part of the greater Malay Peninsula—makes up the south of the country, forming the fifth region. Although dominated by north-south mountains, this region is also noted for its coastal beaches and its many islands, some formed of limestone.
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