| 释义 |
laterite Min.|ˈlætəraɪt|
[f. L. later brick + -ite1.]
a. A red, porous, ferruginous clayey substance, forming the surface covering in some parts of India, south-western Asia, and other tropical and sub-tropical regions, which is soft when first dug but hardens irreversibly to the consistency of rock when exposed to the air.
b. Applied loosely to various reddish or iron-rich surface materials in the tropics and sub-tropics.
c. Soil Science. Any soil or soil horizon characterized by a high proportion of sesquioxides, esp. of aluminium and iron, and an unusually low proportion of alkali metals, alkaline earths, and combined silica, such as occurs as a product of chemical weathering in hot climates with periods of abundant rain; esp. one which hardens on exposure to air or is derived from one already exposed.
The use and proper application of the word have been the subject of much debate.
1807F. Buchanan Journey from Madras II. xii. 441 What I have called indurated clay is not the mineral so called by Mr. Kirwan. It..is one of the most valuable materials for building. It is diffused in immense masses, without any appearance of stratification, and is placed over the granite that forms the basis of Malayala... As it is usually cut into the form of bricks.., in several of the native dialects, it is called the brick-stone (Itica cullu). Where, however, by the washing away of the soil, part of it has been exposed to the air, and has hardened into a rock, its colour becomes black, and its pores and inequalities give it a kind of resemblance to the skin of a person affected with cutaneous disorders; hence in the Tamul language it is called Shuri cull, or itch-stone. The most proper English name would be Laterite. Ibid. 460 In general, the Laterite, or brick-stone, comes very near the surface. 1871Tylor Prim. Cult. I. 53 In the gravel-beds of Europe, the laterite of India, and other more superficial localities. 1893R. D. Oldham Man. Geol. India (ed. 2) xv. 385 The origin of laterite is still wrapt in obscurity. Ibid., According to some geologists this laterite [of Buchanan] is in reality a soil and formed by the direct decomposition in situ of the underlying rock. 1898Agric. Ledger (Calcutta) V. ii. 34 If..it is difficult for the Geologist to decide what is ‘laterite’, it becomes practically impossible for the agriculturist to say what is a ‘laterite soil’. Those ‘laterite soils’, that is, soils lying on or adjacent to what had every appearance of being laterite rock, which I have seen, had all a bright red appearance when dry; but as will be seen when discussing the analyses of the samples.., some at least of these are probably not true laterite. 1909Geol. Mag. Decade V. VI. 431 The term ‘laterite’ has been used, in the Malay Peninsula at least, for many years by a large body of engineers for what are essentially masses of iron oxide replacing portions of weathered rock and filling fissures in such rocks near the surface. This (Malayan) laterite..is largely used for public works. 1910Ibid. VII. 444 The foregoing representatives of the class of more or less ferruginous and aluminous deposits which in the Guianas..have been termed ‘laterite’ do not possess, except in the case of the concretionary ironstones, the property..of ‘setting’ or hardening on exposure to the atmosphere. Parts of them agree to some extent with what has been laid down as the modern scientific qualification for a rock to be termed ‘laterite’—the fact that they are ‘essentially characterized by the presence of free hydrate of alumina’. 1911Ibid. VIII. 565 Laterite (or rather some varieties of it) is formed by a process..by which certain rocks undergo superficial decomposition, with the removal in solution of combined silica, lime, magnesia, soda, and potash, and with the residual accumulation..of a hydrated mixture of oxides of iron, aluminium, and titanium, with, more rarely, manganese. Ibid., The property of hardening on exposure to the air is characteristic of many varieties of laterite, but it is not essential property. 1927Jrnl. Agric. Sci. XVII. 546 It is..suggested that where the silica/alumina ratio in the clay fraction [of a soil] falls below 2·0 the soil should be described as ‘lateritic’, and where this ratio falls below 1·33 the soil should be described as laterite. 1932G. W. Robinson Soils xiii. 279 Many of the descriptions of the supposed laterites merely relate to red soils... It is now generally agreed that the terms laterite and lateritic should be restricted to materials characterised by excess of sesquioxides. 1949Publ. Inst. Nat. pour l'Étude Agron. du Congo Belge Sér. Sci. No. 46. 7 The word ‘laterite’ is used by us for the sesquioxide-rich, highly weathered clayey materials that change irreversibly to concretions, hardpans, or crusts, when dehydrated, and for the hardened relicts of such materials, more or less mixed with entrapped quartz and other materials. 1966D. Forbes Heart of Malaya iii. 35 It [sc. a bungalow] was set on a hillside..at the end of a three-mile estate road of red laterite. 1967Nat. Geographic July 110/2 [Thailand.] A foreman said this was laterite, a low-grade iron ore, good for making roads and filling land. 1970E. M. Bridges World Soils ix. 72/1 Laterite..is formed by an accumulation in the soil of sesquioxidic material.
attrib.1851R. F. Burton Goa 176 A pile of laterite rock rising abruptly from a level expanse of sand. 1886Guillemard Cruise Marchesa II. 327 The red laterite roads. 1898[see above]. 1906Daily Chron. 24 Aug. 6/5 The soil and the climate of Seychelles are evidently favourable to the growth of Para rubber, which thrives even in laterite soils where no other plants are at present growing. |