@article{BBPC:BBPC1982200003, author = "Karl Hans Wedepohl", abstract = "The three major units of the earth are the core, the mantle and the crust. The material of the earth's mantle and core originated 4.6 billion years ago from condensation products of solar gases. The continental crust is on the average 40 km thick and varies in composition and age (≤ 3.8 · 109 years) while the present oceanic crust is about 7 km thick, composed mainly of basalt and less than 200 million years old. The renewal and the growth of the oceanic crust from partial melting of peridotites in the upper mantle is observable in the basaltic magmatism at mid-ocean ridges and in the drift of the continents (˜ cm per year). The crustal growth is compensated by subduction of crustal plates into the mantle at some continental margins such as in the Circum-Pacific. The oceanic basalts gain water through reactions with sea water and lose this during subduction (at about 900°C) to the overlying mantle materials (peridotites). Partial melting of mantle materials (and differentiation of primary melts) results in the formation of basaltic, andesitic or other magmas and contributes substantially to the growth of the continents. This direct or indirect origin of andesitic magmas from water containing peridotites is explained on the base of melting experiments and partition data of trace elements between melts and their potential source rocks. The majority of minerals in magmatic rocks are not stable under earth's surface conditions. They react with the degassing products of the earth's mantle (H2O, CO2, SO2, HCl) and with photochemically produced oxygen to form weathering and sedimentary minerals (OH containing silicates, CaCO3, CaSO4, NaCl etc.). Erosion, water transport and sedimentation control the material balance of elements near the earth's surface. The original sediments which contain water and other specific compounds are buried with time in deeper and warmer crustal levels. Their minerals reequilibrate at increasingly higher temperatures and pressures. Finally at 600–700°C, depending on the availability of water, they partially melt to form granitic magmas. The difference in density between the source rocks and the melts causes the uprise of granitic magmas. This process results in a chemical fractionation between the lower and the upper continental crust over long geologic time. – Summarizing the important observations of this report, water has controlled major processes in the outer shells of the earth.", doi = "10.1002/bbpc.198200003", issn = "0005-9021", journal = "Berichte der Bunsengesellschaft f{\"u}r physikalische Chemie", keywords = "Chemische Verwitterung, Geochemie, Nat{\"u}rliche Schmelzen (Partialschmelzen), Phasenumwandlungen, Verteilungsgleichgewichte", number = "11", pages = "975--985", publisher = "Wiley-VCH Verlag GmbH {\&} Co. KGaA", title = "{S}toffbestand und {E}ntwicklung des {\"a}u{\ss}eren {E}rdk{\"o}rpers", url = "http://dx.doi.org/10.1002/bbpc.198200003", volume = "86", year = "1982", }