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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 ]
Rendzina (or rendsina) is a soil type recognized in various soil classification systems, including those of Britain [1] and Germany [2] as well as some obsolete systems. They are humus-rich shallow soils that are usually formed from carbonate- or occasionally sulfate-rich parent material. [2] Rendzina soils are often found in karst and ...
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.
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.
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 ]
Tufa columns at Mono Lake, California. Tufa is a variety of limestone formed when carbonate minerals precipitate out of water in unheated rivers or lakes. Geothermally heated hot springs sometimes produce similar (but less porous) carbonate deposits, which are known as travertine or thermogene travertine.
While micromorphological descriptions may begin in the field with the use of a 10x hand lens, much more can be described using thin sections made of the soil with the aid of a petrographic polarizing light microscope. The soil can be impregnated with an epoxy resin, but more commonly with a polyester resin (crystic 17449) and sliced and ground ...