Finding Laterites

Abstract

At some time laterite has existed everywhere that the parameters for its production have prevailed. The frequently changing temperature and rainfall conditions throughout geologic history have presented the environment necessary for accumulation and induration of iron salts to much of the earth’s surface within the boundaries of the temperate zone between 35° N and 35° S. As iron, aluminum, and silica are sufficiently abundant in surface rocks, it was only necessary that the proper concentration be present when lateritizing conditions existed. The environment which produces laterites is severe, and severity is not usually of long duration in geologic terms. Incomplete weathering when a laterite-inducmg environment prevailed seems to be the principal factor which would have prevented laterite formation from rocks containing the necessary elements. Complete weathering is necessary to free the elements and create the sesquioxides which must be present. Insufficiently weathered igneous and metamorphic rocks of the Appalachians are an example of incomplete weathering during the periods of necessary conditions.