Plate 5 Photomicrographs of miscellaneous sedimentary rocks. (A) Lateritic bauxite with well-developed
orbicular texture. The individual orbs are about 0.5 cm in diameter, Le Baux, France. For discussion of origin, see
Section 2.3.3.1. (xl0) (B) Sedimentary ironstone, Northampton, Middle Jurassic, England. Note the concentric
structure of the chamosite ooids. For discussion of origin, see Section 9.4.1. (x20) (C) Guano phosphate deposit, St.
Helena, South Atlantic. For discussion of origin, see Section 9.5.1. (xS) (D) Nodular anhydrite from the modem
sabldaa of Abu Dhabi, United Arab Emirates. For discussion of origin, see Section 9.6.3. (x20) (E) Chert formed by
the silicification of skeletal lime mudstone. Chalk, Upper Cretaceous, Dover, England. Polarized light. (x60) (F)
Silicified sandstone with chalcedonic sponge spicules and intergranular cement. Sandgate Beds, Lower
Cretaceous, Leith Hill, Surrey. Polarized light. (x20)