ABSTRACT
Weathering is an important process in the transformation of geologic materials, as important as diagenesis. In contrast to diagenesis, which changes loose sediments into a consolidated material called rock, weathering turns solid rock into loose material. Weathering includes a group of processes that transforms rocks into mechanically weak, easily eroded material. The ground surface and the upper part of the zone of seasonal temperature variation are subject to significant and repeated temperature changes that cause physical weathering of geological materials. Freezing is an issue that must be considered in the design of caps over highly toxic waste repositories. The waste is covered with a multi-layer cover that must prevent to the maximum possible extent the penetration of meteoric water into the landfill. Physico-chemical weathering processes are reactions between solids and water. The water can be surface water or groundwater. Biology also plays an important role in some reactions.
