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  2. Marine biogeochemical cycles - Wikipedia

    en.wikipedia.org/wiki/Marine_biogeochemical_cycles

    There are biogeochemical cycles for the elements calcium, carbon, hydrogen, mercury, nitrogen, oxygen, phosphorus, selenium, and sulfur; molecular cycles for water and silica; macroscopic cycles such as the rock cycle; as well as human-induced cycles for synthetic compounds such as polychlorinated biphenyl (PCB). In some cycles there are ...

  3. Carbonate–silicate cycle - Wikipedia

    en.wikipedia.org/wiki/Carbonate–silicate_cycle

    The inorganic cycle begins with the production of carbonic acid (H 2 CO 3) from rainwater and gaseous carbon dioxide. [6] Due to this process, normal rain has a pH of around 5.6. [7] Carbonic acid is a weak acid, but over long timescales, it can dissolve silicate rocks

  4. Weathering - Wikipedia

    en.wikipedia.org/wiki/Weathering

    The materials left after the rock breaks down combine with organic material to create soil. Many of Earth's landforms and landscapes are the result of weathering, erosion and redeposition. Weathering is a crucial part of the rock cycle; sedimentary rock, the product of weathered rock, covers 66% of the Earth's continents and much of the ocean ...

  5. Geochemical cycle - Wikipedia

    en.wikipedia.org/wiki/Geochemical_cycle

    Some [who?] may use the terms biogeochemical cycle and geochemical cycle interchangeably because both cycles deal with Earth's reservoirs.However, a biogeochemical cycle refers to the chemical interactions in surface reservoirs such as the atmosphere, hydrosphere, lithosphere, and biosphere [citation needed] whereas a geochemical cycle refers to the chemical interactions that exist in crustal ...

  6. Desert pavement - Wikipedia

    en.wikipedia.org/wiki/Desert_pavement

    A desert pavement, also called reg (in western Sahara), serir (in eastern Sahara), gibber (in Australia), or saï (in central Asia) [1] is a desert surface covered with closely packed, interlocking angular or rounded rock fragments of pebble and cobble size. They typically top alluvial fans. [2] Desert varnish collects on the exposed surface ...

  7. Geology - Wikipedia

    en.wikipedia.org/wiki/Geology

    Solidified lava flow in Hawaii Sedimentary layers in Badlands National Park, South Dakota Metamorphic rock, Nunavut, Canada. Geology (from Ancient Greek γῆ (gê) 'earth' and λoγία () 'study of, discourse') [1] [2] is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. [3]

  8. Rock cycle - Wikipedia

    en.wikipedia.org/wiki/Rock_cycle

    This diamond is a mineral from within an igneous or metamorphic rock that formed at high temperature and pressure. The rock cycle is a basic concept in geology that describes transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous.

  9. Capillary pressure - Wikipedia

    en.wikipedia.org/wiki/Capillary_pressure

    The wetting phase is identified by its ability to preferentially diffuse across the capillary walls before the non-wetting phase. The "wettability" of a fluid depends on its surface tension, the forces that drive a fluid's tendency to take up the minimal amount of space possible, and it is determined by the contact angle of the fluid. [ 1 ]