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  2. Chalk - Wikipedia

    en.wikipedia.org/wiki/Chalk

    Chalk and other forms of limestone may be used for their properties as a base. [23] Chalk is a source of quicklime by thermal decomposition, or slaked lime following quenching of quicklime with water. [24] In agriculture, chalk is used for raising pH in soils with high acidity. [25] Small doses of chalk can also be used as an antacid. [26]

  3. Marine sediment - Wikipedia

    en.wikipedia.org/wiki/Marine_sediment

    Marine sediment, or ocean sediment, or seafloor sediment, are deposits of insoluble particles that have accumulated on the seafloor.These particles either have their origins in soil and rocks and have been transported from the land to the sea, mainly by rivers but also by dust carried by wind and by the flow of glaciers into the sea, or they are biogenic deposits from marine organisms or from ...

  4. Calcareous - Wikipedia

    en.wikipedia.org/wiki/Calcareous

    Calcareous soils are relatively alkaline, in other words they have a high pH.They are characterized by the presence of calcium carbonate in the parent material; the carbonate-ion is a base.

  5. Cretaceous - Wikipedia

    en.wikipedia.org/wiki/Cretaceous

    The Cretaceous is justly famous for its chalk; indeed, more chalk formed in the Cretaceous than in any other period in the Phanerozoic. [27] Mid-ocean ridge activity—or rather, the circulation of seawater through the enlarged ridges—enriched the oceans in calcium ; this made the oceans more saturated, as well as increased the ...

  6. Calcareous grassland - Wikipedia

    en.wikipedia.org/wiki/Calcareous_grassland

    Calcareous grassland (or alkaline grassland) is an ecosystem associated with thin basic soil, such as that on chalk and limestone downland. [1] Ranscombe Farm, Medway on the North Downs. In June, these meadows are covered with chalk grassland flowers.

  7. Pelagic sediment - Wikipedia

    en.wikipedia.org/wiki/Pelagic_sediment

    Red clay, also known as either brown clay or pelagic clay, accumulates in the deepest and most remote areas of the ocean. It covers 38% of the ocean floor and accumulates more slowly than any other sediment type, at only 0.1–0.5 cm/1000 yr. [1] Containing less than 30% biogenic material, it consists of sediment that remains after the dissolution of both calcareous and siliceous biogenic ...

  8. Caliche - Wikipedia

    en.wikipedia.org/wiki/Caliche

    Higher rainfall leaches excess calcium completely from the soil, while in very arid climates, rainfall is inadequate to leach calcium at all and only thin surface layers of calcite are formed. Plant roots play an important role in caliche formation, by releasing large amounts of carbon dioxide into the A horizon of the soil. Carbon dioxide ...

  9. Marine biogeochemical cycles - Wikipedia

    en.wikipedia.org/wiki/Marine_biogeochemical_cycles

    Phosphorus-rich deposits have generally formed in the ocean or from guano, and over time, geologic processes bring ocean sediments to land. Weathering of rocks and minerals release phosphorus in a soluble form where it is taken up by plants, and it is transformed into organic compounds.