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Chalk is a fine-textured, earthy type of limestone distinguished by its light colour, softness, and high porosity. [ 1 ] [ 2 ] It is composed mostly of tiny fragments of the calcite shells or skeletons of plankton , such as foraminifera or coccolithophores . [ 1 ]
The Chalk Group is now divided into a White Chalk Subgroup and a Grey Chalk Subgroup, both of which are further subdivided into formations.These modern divisions replace numerous earlier divisions, references to which occur widely on geological maps and in other geological literature.
These oozes form slowly under low-energy environments, and necessitate higher seawater saturation states or a deeper CCD (see supersaturation and precipitation vs. undersaturation and dissolution). Therefore, in shallow CCD conditions ( i.e. , undersaturation of calcium carbonate at depth), stable, non-calcareous sediments such as siliceous ...
Plants on calcareous grassland are typically short and hardy, and include grasses and herbs such as clover.Calcareous grassland is an important habitat for insects, particularly butterflies and ants, [2] and is kept at a plagioclimax by grazing animals, usually sheep and sometimes cattle.
Sabkha deposits are believed to form some of the major subsurface hydrocarbon reservoirs in the Middle East (and elsewhere). The source of these hydrocarbons (both gas and oil) may be the microbial mats and mangrove paleosoils , found in the sabkha sequence, that have total organic carbon up to 8.2% and hydrogen indices typical of marine type ...
Soiling is the accumulation of material on light-collecting surfaces in solar power systems. The accumulated material blocks or scatters incident light, which leads to a loss in power output. Typical soiling materials include mineral dust, bird droppings, fungi, lichen, pollen, engine exhaust, and agricultural emissions.
Soils at the bottom of a hill will get more water than soils on the slopes, and soils on the slopes that face the sun's path will be drier than soils on slopes that do not. [ 64 ] In swales and depressions where runoff water tends to concentrate, the regolith is usually more deeply weathered, and soil profile development is more advanced. [ 65 ]
Soil piping is a particular form of soil erosion that occurs below the soil surface. [237] It causes levee and dam failure, as well as sink hole formation. Turbulent flow removes soil starting at the mouth of the seep flow and the subsoil erosion advances up-gradient. [ 238 ]