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Angadipuram Laterite is a National Geological Monument identified in Angadipuram town in Malappuram district in the southern Indian state of Kerala, India. The special significance of Angadipuram to laterites is that it was here that Dr. Francis Buchanan-Hamilton, a professional surgeon, gave the first account of this rock type, in his report of 1807, as "indurated clay", ideally suited for building construction.〔 This formation falls outside the general classification of rocks namely, the igneous, metamorphic, or sedimentary rocks but is an exclusively "sedimentary residual product". It has a generally pitted and porous appearance. The name laterite was first coined in India, by Buchanan and its etymology is traced to the Latin word "letritis" that means bricks.〔〔 This exceptional formation is found above parent rock types of various composition namely, charnockite, leptynite, anorthosite and gabbro in Kerala. It is found over basalt in the states of Goa, Maharashtra and in some regions of Karnataka. In Gujarat in western India, impressive formations of laterite are found over granite, shale and sandstone.. Apart from its use as bricks in building construction, it has other substantial economic value, since it has been established that laterites are closely juxtaposed with aluminium ore (bauxite), iron ore and nickel ore mineral deposits in many parts of Kerala.〔 The GSI has erected a monument at Angadipuram (see picture) where the laterite formations were first identified, as one of the 26 monuments declared as National Geological Monuments, on the occasion of the "International Conference on Laterization" held in 1979.〔 Angadipuram is also well known as a pilgrimage centre for its famous temples, the Thirumandhamkunnu temple and the Tali temple. ==Geography== Angadipuram is situated in the Malappuram district, which lies in northern Kerala, and is bounded on the north by Wayanad and Kozhikkode districts, on the northeast by Tamil Nadu, on the southeast and south by Palakkad District, on the southwest by Thrissur District, on the west by the Arabian Sea, and on the northwest by Kozhikode District (see Kerala eco zones map). The geographical distribution of laterite is not limited to Angadipuram in Malappuram district but it is also found in the midland regions and highlands of Kerala. Its occurrence extends to Aleppey, Quilon, Thiruvananthapuram, Kottayam, Trichur and Cannanore districts. Overall, in the landform of Kerala which has seven landscape ecological zones, laterites account for a major share of 50%. This land form comprises lateritic mesa, mounds, slopes and ridges. This dominant laterite setting is delimited between altitudes and (though found up to elevation and extends from the northern end to the southern tip of the state. Further, as the topography changes a few kilometers from the sea to the east, there are numerous valleys called ''elas'' where patches of paddy fields, coconut and arecanut groves are seen. Incidence of laterite in other parts of India is reported in the states of Karnataka Maharashtra and Gujarat.〔 Apart from India, its global occurrence in the form of vast deposits of lateritic bauxites with rich production is reported in Australia, Brazil, Guinea, Guyana, Suriname and Venezuela.〔 ;Climate The intense southwest Monsoon rainfall in Kerala (average annual rainfall is 3,107 mm) coupled with high temperatures (mean annual temperatures range from 25 to 27.5 °C in the coastal lowlands to 20 to 22.5 °C in the eastern highlands) and lush vegetation (belongs to the Malabar Coast moist forests of a tropical moist broadleaf forest ecoregion of southwestern India) has accentuated the chemical processes over the base rocks, which has resulted in the formation of laterites. In view of these conditions, the laterization process, which results in formation of laterites, is called the "Tropical disease of rocks".〔"GSI" p. 46〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Angadipuram Laterite」の詳細全文を読む スポンサード リンク
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