Progress towards the development of a better understanding of the formation of geological patterns in wet systems due to precipitation and dissolution is reviewed. Emphasis is placed on the formation of terraces, stalactites, stalagmites and other carbonate patterns due to precipitation from flowing supersaturated solutions and the formation of scallops by dissolution in undersaturated turbulent fluids. In addition, the formation of spherulites, dendrites and very large, essentially euhedral,

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... ystals is discussed. In most cases, the formation of very similar patterns as a result of the freezing/melting of ice and the precipitation/dissolution of minerals strongly suggests that complexity associated with aqueous chemistry, interfacial chemistry and biological processes has only a secondary effect on these pattern formation processes.