Materials such as; paper, wood, wallboard, fiberglass, plastics, metal, glass, ceramic, stone, concrete and asphalt, often need to be impervious to water, oil, grease or even oxygen. These materials ...

Karst formations: Sedimentary carbonate rock (limestone, dolomite) that has been eroded by water. Limestone: Sedimentary rock composed of calcium carbonate. Microbial mat: Filamentous microbes ...