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Chalk is so common in Cretaceous marine beds that the Cretaceous Period was named for these deposits. The name Cretaceous was derived from Latin creta, meaning chalk. [10] Some deposits of chalk were formed after the Cretaceous. [11] The Chalk Group is a European stratigraphic unit deposited during the late Cretaceous Period.
Liming is the application of calcium- (Ca) and magnesium (Mg)-rich materials in various forms, including marl, chalk, limestone, burnt lime or hydrated lime to soil. [1] In acid soils , these materials react as a base and neutralize soil acidity .
Expansive soils are the most problematic in regions with very defined wet and dry periods, as opposed to areas that maintain a certain level of moisture throughout the year, as this annual cycle causes the soils to expand and swell every year. [3] Water can also be introduced into the soil through people, or their infrastructure.
Water in aquifers underground can be exposed to levels of CO 2 much higher than atmospheric. As such water percolates through calcium carbonate rock, the CaCO 3 dissolves according to one of the trends above. When that same water then emerges from the tap, in time it comes into equilibrium with CO 2 levels in the air by outgassing its excess CO ...
The products of chalk weathering are dissolved in rainwater and are transported in stream flow. Chalk streams transport little suspended material (unlike most rivers), but are considered "mineral-rich" due to the dissolved calcium and carbonate ions. The surface water of chalk streams is commonly described as "gin clear".
Pores (the spaces that exist between soil particles) provide for the passage and/or retention of gasses and moisture within the soil profile.The soil's ability to retain water is strongly related to particle size; water molecules hold more tightly to the fine particles of a clay soil than to coarser particles of a sandy soil, so clays generally retain more water. [2]
Soil moisture is the water content of the soil. It can be expressed in terms of volume or weight. Soil moisture measurement can be based on in situ probes (e.g., capacitance probes, neutron probes) or remote sensing methods. [1] [2] Water that enters a field is removed from a field by runoff, drainage, evaporation or transpiration. [3]
Calcium carbonate (limestone or chalk) decomposes into calcium oxide and carbon dioxide when heated. The chemical reaction is as follows: CaCO 3 → CaO + CO 2 The reaction is used to make quick lime, which is an industrially important product. Another example of thermal decomposition is 2Pb(NO 3) 2 → 2PbO + O 2 + 4NO 2.