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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.
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. Additionally, these soils may have a calcic horizon, a layer of secondary accumulation of carbonates (usually calciumcarbonate or magnesiumcarbonate) in ...
Chalk is a soft, white, porous, sedimentary carbonate rock.It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor.
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.
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 ]
Residuum is weathered rock that is not transported by erosion, contributing in time to the formation of soil.It is distinguished from other types of parent material in that it is composed solely of mineral, not organic, material, and it remains in place rather than being moved by the action of wind, water, or gravity.
Natural salt pans or salt flats are flat expanses of ground covered with salt and other minerals, usually shining white under the sun. They are found in deserts and are natural formations (unlike salt evaporation ponds, which are artificial). A salt pan forms by evaporation of a water pool, such as a lake or pond.
Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ice formed over a range of years. Cores are drilled with hand augers (for shallow holes) or powered drills; they can reach depths of over two miles (3.2 km), and contain ice up to 800,000 years old.