<P> The French surfaced roads in the Cambodia, Thailand and Viet Nam area with crushed laterite, stone or gravel . Kenya, during the mid-1970s, and Malawi, during the mid-1980s, constructed trial sections of bituminous - surfaced low - volume roads using laterite in place of stone as a base course . The laterite did not conform with any accepted specifications but performed equally well when compared with adjoining sections of road using stone or other stabilized material as a base . In 1984 US $40,000 per 1 km (0.62 mi) was saved in Malawi by using laterite in this way . </P> <P> Bedrock in tropical zones is often granite, gneiss, schist or sandstone; the thick laterite layer is porous and slightly permeable so the layer can function as an aquifer in rural areas . One example is the Southwestern Laterite (Cabook) Aquifer in Sri Lanka . This aquifer is on the southwest border of Sri Lanka, with the narrow Shallow Aquifers on Coastal Sands between it and the ocean . It has considerable water - holding capacity, depending on the depth of the formation . The aquifer in this laterite recharges rapidly with the rains of April--May which follow the dry season of February--March, and continues to fill with the monsoon rains . The water table recedes slowly and is recharged several times during the rest of the year . In some high - density suburban areas the water table could recede to 15 m (50 ft) below ground level during a prolonged dry period of more than 65 days . The Cabook Aquifer laterites support relatively shallow aquifers that are accessible to dug wells . </P> <P> In Northern Ireland, phosphorus enrichment of lakes due to agriculture is a significant problem . Locally available laterite--a low - grade bauxite rich in iron and aluminium--is used in acid solution, followed by precipitation to remove phosphorus and heavy metals at several sewage treatment facilities . Calcium -, iron - and aluminium - rich solid media are recommended for phosphorus removal . A study, using both laboratory tests and pilot - scale constructed wetlands, reports the effectiveness of granular laterite in removing phosphorus and heavy metals from landfill leachate . Initial laboratory studies show that laterite is capable of 99% removal of phosphorus from solution . A pilot - scale experimental facility containing laterite achieved 96% removal of phosphorus . This removal is greater than reported in other systems . Initial removals of aluminium and iron by pilot - scale facilities have been up to 85% and 98% respectively . Percolating columns of laterite removed enough cadmium, chromium and lead to undetectable concentrations . There is a possible application of this low - cost, low - technology, visually unobtrusive, efficient system for rural areas with dispersed point sources of pollution . </P> <P> Ores are concentrated in metalliferous laterites; aluminium is found in bauxites, iron and manganese are found in iron - rich hard crusts, nickel and copper are found in disintegrated rocks, and gold is found in mottled clays . </P>

Where is the laterite soil found in india