variable; frequently red, brown, greenish, yellow, grey, white.
Texture: Medium-grained. Usually well sorted, that is grains all about
the same size; grains sub angular to rounded (sandstone).
Structure: Bedding usually apparent; current bedding and ripple marks
common; graded bedding may occur. Concretions and fossils may be found.
Mineralogy: Quartz is the main component but is often accompanied by feldspar,
mica or other minerals. The grains may be cemented by silica, calcite
or iron oxides.
Field relations: Sandstones are associated with most other sedimentary
rocks. Most sands accumulated either in water, usually the sea, or as
wind-blown deposits in arid continental areas. Desert sandstones tend
to be red, and the individual sand grains are often almost spherical and
(Hamilton et al 1976,