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Because chalk is porous, chalk downland usually holds a large water table, providing a natural reservoir that releases water slowly through dry seasons.

Chalk has been quarried from prehistory, providing building material and marl for fields. In southeast England, deneholes are a notable example of ancient chalk pits.

The Chalk Formation is a European stratigraphic unit in the upper Cretaceous period. This includes the famous White cliffs of Dover1980 The white cliffs of Dover immortalized in popular song and verse (by Blur and others), are cliffs facing the Strait of Dover near the major port town of Dover, England, in the county of Kent. The cliff face, which reaches up to 350 feet high, owes it of KentThis article is about the English county of Kent. See also Kent (disambiguation). Kent is a county in England, south-east of London. The county town is Maidstone. Kent has land borders with East Sussex, Surrey and Greater London, and a defined boundary wi in England, which formed entirely of chalk deposits.

BlackboardA blackboard also called a chalkboard is a surface on which markings made with chalk are visible. It is used as a surface on which to write. A blackboard can simply be a piece of board painted with matte dark paint (usually dark green or black), but a mor chalk is a substance used for drawing on rough surfaces, as it readily crumbles leaving particles that stick loosely to these surfaces. Blackboard chalk, often supplied in sticks about 5 cm long, is not actually made from the mineral chalk but from gypsumGypsum is a very soft mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 2HO. Chemical structure Heating gypsum above approximately 150°C (302°F) partially dehydrates the mineral, by driving off exactly 75% of the water containe ( calcium sulfate). Similarly, the "chalk" used by tailors is usually made from talcTalc is a mineral composed of hydrated magnesium silicate with the chemical formula H Mg( SiO) or Mg Si O( OH). It occurs as foliated to fibrous masses, its monoclinic crystals being so rare as to be almost unknown. It has a perfect basal cleavage, the fo ( magnesiumMagnesium is the chemical element in the periodic table that has the symbol Mg and atomic number 12. Magnesium is the eighth most abundant element and constitutes about 2% of the Earth's crust, and it is the third most plentiful element dissolved in seawa silicate).

In military terminology, a chalk is a specific aircraft load, especially a group of airborne soldiers which deploy from a single aircraft. U.S. Army Ranger Chalk Four was the group which took the initial casualties in the Battle of Mogadishu in Somalia.