Residual laterite and bauxite ores are also found in the southern hills. Angkorian builders mainly used sandstone and laterite as temple building materials. The temple was made of whitish sandstone over foundations of laterite blocks. The Lingaraja temple faces east and is built of sandstone and laterite. Angkorian builders used brick, sandstone, laterite and wood as their materials. The pit was backfilled and capped with a mound overlaid with scattered laterite blocks. Minerals formed in laterite nickel deposits include gibbsite. The two libraries are of brick, laterite and sandstone. This style preferred to use brick, sandstone, and laterite. The rock is basalt, which has given rise to secondary alteration known as laterite. The lower basin is made up of young sediments, including laterite and recent alluvium. Lateritic soils form the uppermost part of the laterite cover. The hills have red laterite soil that is porous. Houses were constructed with walls of wooden planks, mud, laterite brick, or stone. The upper reaches of the Ajay pass through hilly regions with laterite soil.