Next to climate and grape variety, one of the most important factors influencing the quality of wine. The different soil types have developed over millions of years through physical and chemical weathering of rocks and through humification of organic matter. During physical weathering, natural forces such as wind, water, heat, cold and ice first cause the rock formations to be mechanically broken up into pebbles and gravel. Strong temperature contrasts, friction and shear forces as well as frost splitting by frozen water in rock fissures play an important role in this process. Chemical weathering processes such as oxidation, solution processes and acid attacks attack the mineral lattice structure of the rocks. In the process, easily water-soluble minerals such as carbonates and sulphates are first dissolved, and the rock slowly decomposes into grime, sand, silt or clay. Every rock, even the hardest granite or quartz, will eventually disintegrate into dust, even if it takes many millions of years.