GEOLOGY & PLANETARY SCIENCE A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site chalk Chalk cliffs, Dorset, England A soft, porous form of limestone, composed mainly of calcium carbonate (CaCO3) with varying amounts of silica, quartz, feldspar, or other impurities. Chalk is generally gray-white or yellow-white and is derived chiefly from the remains of small marine organisms. Embedded flint nodules are commonly found in chalk beds. Related category    • GEOLOGY AND PLANETARY SCIENCE Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP