Silcretes (silica-rich duricrusts) form through the mobilization, transport, and re-precipitation of silica within near-surface soil/regolith profiles, a process favored by arid to semi-arid climatic conditions with poor drainage (allowing prolonged residence time and evaporative concentration of silica-bearing groundwater) and elevated (alkaline) groundwater pH, which increases the solubility and mobility of silica prior to its precipitation as the environment becomes locally more concentrated or pH shifts.