The Cretaceous or Chalk Formation. (_Wond._ p. 296). A marine formation, comprising a vast series of beds of limestone, sandstone, marl, and clay, &c.; characterized by remains of extinct zoophytes, mollusks, cephalopods, echinoderms, crustaceans, fishes, &c.; lacertians, crocodilians, chelonians, and other extinct reptiles; drifted coniferous and dicotyledonous wood and foliage, fuci, &c. _Subdivisions_:-- 1. The _Maestricht beds_. Friable coralline and shelly limestones, with flints and chert. 2. _Upper Chalk_, with flints } _Craie blanche_ of the French } geologists. 3. _Lower Chalk_, without flints } 4. _Chalk-marl_ _Craie tufeau._ 5. _Firestone_, Malm-rock, Upper } _Glauconie crayeuse._ Greensand, or Glauconite } 6. _Galt_, or Folkstone-marl _Glauconie sableuse._ 7. _Shanklin_, or Lower Greensand. { _Formation néocomien_; which { is divided into _N. supérieur_, { the English upper divisions { of the Greensand or Kentish { rag; and _N. inférieur_, the { lower beds of sand and clay, { of the southern shore of the { Isle of Wight, at Atherfield.[18] [18] Another subdivision, with _other_ names (chiefly derived from French localities), has lately been proposed by M. D'Orbigny; which I notice with the more regret, since this eminent naturalist formerly repudiated the censurable practice of many modern systematists, of changing established names of strata and fossils, without any just cause. The British geologist will smile to see the Wealden Formation--so eminently distinguished in England and Germany by its extent, thickness, and remarkable fauna and flora,--ranked as a subordinate member of the "_Formation néocomien_," of France. _Obs._--The Maestricht beds are chiefly composed of fawn-coloured limestones of friable texture; containing peculiar species of corals, shells, fishes, reptiles, &c. The _Chalk_ is generally white, but in some localities is of a deep red, in others of a yellow colour; nodules, layers, and veins of flint occur in the upper, but are seldom present in the lower chalk. The _Marl_ is an argillaceous limestone, which generally prevails beneath the white chalk; it sometimes contains a large intermixture of green or chlorite sand, and then is called _Firestone_, or _Glauconite_. The _Galt_ is a stiff, blue or blackish clay, abounding in shells which frequently retain their pearly lustre. The _Greensand_ is a triple alternation of sands and sandstones with clays; and beds of cherty limestone called _Kentish Rag_.