The Needles, situated off the Isle of Wight, are part of the extensive Southern England Chalk Formation.
"Nitzana Chalk curves" situated at Western Negev, Israel, are chalk deposits formed in the Mesozoic era's Tethys Ocean
Open chalk pit, Seale, Surrey, UK
Chalk from the White Cliffs of Dover, England
Former underground chalk mine in Meudon, France
Chalk in different colors
Child drawing with sidewalk chalk

Soft, white, porous, sedimentary carbonate rock.

- Chalk

500 related topics



Students writing on a blackboard in a village school in Laos, 2007
A modern chalkboard, 2014
A quadruple blackboard at the Helsinki University of Technology, 2005
Cardboard box of chalk sticks, made in GDR, currently at the MEK
Magnetic blackboard used for play and learning at the children's museum, Kitchener, Canada, 2011
Teacher explaining the decimal system of weights using a blackboard, Guinea-Bissau, 1974
Man writing on a blackboard in Guinea-Bissau in the open air, 1974
Atatürk using a blackboard to teach the new Turkish alphabet in Kayseri, 1928

A blackboard (also known as a chalkboard) is a reusable writing surface on which text or drawings are made with sticks of calcium sulphate or calcium carbonate, known, when used for this purpose, as chalk.


Geological period that lasted from about 145 to 66 million years ago .

The impact of a meteorite or comet is today widely accepted as the main reason for the Cretaceous–Paleogene extinction event.
Drawing of fossil jaws of Mosasaurus hoffmanni, from the Maastrichtian of Dutch Limburg, by Dutch geologist Pieter Harting (1866)
Scipionyx, a theropod dinosaur from the Early Cretaceous of Italy
Map of North America During the Late Cretaceous
A computer-simulated model of surface conditions in Middle Cretaceous, 100 mya, displaying the approximate shoreline and calculated isotherms
Facsimile of a fossil of Archaefructus from the Yixian Formation, China
Derasmosaurus pietraroiae, a rhyncocephalian from the late Early Cretaceous of Italy
Philydrosaurus, a choristodere from the Early Cretaceous of China
Tyrannosaurus rex, one of the largest land predators of all time, lived during the Late Cretaceous
Up to 2 m long and 0.5 m high at the hip, Velociraptor was feathered and roamed the Late Cretaceous
Triceratops, one of the most recognizable genera of the Cretaceous
The azhdarchid Quetzalcoatlus, one of the largest animals to ever fly, lived during the Late Cretaceous
Confuciusornis, a genus of crow-sized birds from the Early Cretaceous
Ichthyornis was a toothed, seabird-like ornithuran from the Late Cretaceous
A scene from the early Cretaceous: a Woolungasaurus is attacked by a Kronosaurus.
Tylosaurus was a large mosasaur, carnivorous marine reptiles that emerged in the late Cretaceous.
Strong-swimming and toothed predatory waterbird Hesperornis roamed late Cretacean oceans.
The ammonite Discoscaphites iris, Owl Creek Formation (Upper Cretaceous), Ripley, Mississippi
A plate with Nematonotus sp., Pseudostacus sp. and a partial Dercetis triqueter, found in Hakel, Lebanon
Cretoxyrhina, one of the largest Cretaceous sharks, attacking a Pteranodon in the Western Interior Seaway

The name is derived from the Latin creta, "chalk", which is abundant in the latter half of the period.


Sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone.

A sample of Miorcani flint from the Cenomanian chalky marl layer of the Moldavian Plateau (ca. 7.5 cm wide)
A piece of flint, 9-10 cm long, weighing 171 grams
Silicified remains of algae and silica pseudomorph after halite in flint. Pebble of Loire near Marcigny, France. Image width: about 5 mm.
Pebble beach made up of flint nodules eroded from the nearby chalk cliffs, Cape Arkona, Rügen, northeast Germany.
Neolithic flint axe, about 31 cm long
A ferrocerium “flint” spark lighter in action
Assorted reproduction firesteels typical of Roman to Medieval period
A flint church – the Parish Church of Saint Thomas, in Cricket Saint Thomas, Somerset, England. The height of the very neatly knapped flints varies between {{convert|3|and|5|in|cm}}.
Close-up of the wall of the Roman shore fort at Burgh Castle, Norfolk, showing alternating courses of flint and brick
A typical medieval wall (with modern memorial) at Canterbury Cathedral – knapped and unknapped ("cobble") flints are mixed with pieces of brick and other stones
Ruins of Thetford Priory show flints and mortar through the whole depth of the wall

It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones.


Material with high plasticity, similar in texture to clay or dough, typically used in domestic construction and repair as a sealant or filler.

Intumescent firestop putty used in a successful fire test, which led to a UL certification listing

Glazing putty is traditionally made by mixing a base of whiting (finely ground chalk) with linseed oil in various proportions.

Chalk Group

Lithostratigraphic unit (a certain number of rock strata) which contains the Upper Cretaceous limestone succession in southern and eastern England.

Brass Point, one of the Seven Sisters
The Needles, (Isle of Wight); part of southern England's extensive chalk outcrop.
Fossil echinoid Echinocorys from the Chalk Group of England
Contact between two units of the lithostratigraphy of South England: the Chalk Group (left, white, upper unit) and the Greensand Formation (right, green, lower unit). Location: Lulworth Cove, near West Lulworth, Dorset, England.
The Wealden Anticline.
Ivinghoe Beacon, Chiltern Hills

It is characterised by thick deposits of chalk, a soft porous white limestone, deposited in a marine environment.

Champagne wine region

Best known for the production of champagne, the sparkling white wine that bears the region's name.

Viticultural zones in the Champagne region
Champagne vineyards in Verzenay in the Montagne de Reims subregion
Statue of Pope Urban II in Champagne
Champagne wine
Grand Cru Champagne from the village of Ambonnay
Vineyard in Champagne
Grand Cru Champagne from the village of Bouzy

Ancient oceans left behind chalk subsoil deposits when they receded 70 million years ago.

Strait of Dover

Strait at the narrowest part of the English Channel, marking the boundary between the Channel and the North Sea, separating Great Britain from continental Europe.

Automatic Identification System display showing traffic in the strait in 2006
Map showing the hypothetical extent of Doggerland (c. 10,000 BCE), which provided a land bridge between Great Britain and continental Europe
NASA Satellite image
December 2002
NASA Terra satellite image, March 2001

The predominant geology on both the British and French sides and on the seafloor is chalk.

White Cliffs of Dover

Region of English coastline facing the Strait of Dover and France.

Extent of the White Cliffs of Dover
The cliffs' multiple layers of flint match those seen across the channel at Cap Gris Nez, France, evidence of a land connection between England and France in prehistoric times.
Evidence of erosion along the cliff top
Landslide near Dover Harbour, June 2012
Exmoor ponies in their native habitat
Peregrine falcon off the cliffs
Rock Samphire (Crithmum maritimum)
The Roman lighthouse at Dover Castle.
Dover Castle with the cliffs in the foreground — circa 1890 to 1900
South Foreland lighthouse
White Cliffs of Dover, seen from France
Samphire Hoe Country Park with local railway and tunnel (not the Channel Tunnel which is nearby).
Shakespeare Cliff, Dover ca. 1905
Lighthouse in Dover
Dover Castle
White Cliffs of Dover footpath
Folkestone and Dover from the International Space Station, showing the White Cliffs and the tracks of ferries.
Vintage photo taken by Walter Mittelholzer, Swiss photographer and aviator, 1933.

The cliff face, which reaches a height of 350 ft, owes its striking appearance to its composition of chalk accented by streaks of black flint, deposited during the Late Cretaceous.


Carbonate mineral and the most stable polymorph of calcium carbonate .

Crystal structure of calcite
Demonstration of birefringence in calcite, using 445 nm laser
One of several calcite or alabaster perfume jars from the tomb of Tutankhamun, d. 1323 BC
Calcite with mottramite
Trilobite eyes employed calcite
Calcite crystals inside a test of the cystoid Echinosphaerites aurantium (Middle Ordovician, northeastern Estonia)
Rhombohedrons of calcite that appear almost as books of petals, piled up 3-dimensionally on the matrix
Calcite crystal canted at an angle, with little balls of hematite and crystals of chalcopyrite both on its surface and included just inside the surface of the crystal
Thin section of calcite crystals inside a recrystallized bivalve shell in a biopelsparite
Grainstone with calcite ooids and sparry calcite cement; Carmel Formation, Middle Jurassic, of southern Utah, USA.
Several well formed milky white casts, made up of many small sharp calcite crystals, from the sulfur mines at Agrigento, Sicily
Reddish rhombohedral calcite crystals from China. Its red color is due to the presence of iron
Cobaltoan, the cobalt-rich variety of calcite
Sand calcites (calcites heavily included with desert sand) in South Dakota, USA
Calcite, butterfly twin, {{nobr|4,0 × 3,3 × 1,6 cm}}. José María Patoni, San Juan del Río, Durango (Mexico)

It is thus etymologically related to chalk.

Nodule (geology)

Small, irregularly rounded knot, mass, or lump of a mineral or mineral aggregate that typically has a contrasting composition, such as a pyrite nodule in coal, a chert nodule in limestone, or a phosphorite nodule in marine shale, from the enclosing sediment or sedimentary rock.

Devonian nodular limestone
Concretionary nodular limestone at Jinshitan Coastal National Geopark, Dalian, China

Chert and flint nodules are often found in beds of limestone and chalk.