ABSTRACT
SANDSTONES are all those medium-grained sedimentary rocks that comprise more than 50% sand-size (0.063-2mm) grains. They are also known as arenites, wackes and grey - wackes. Where the coarse-grained (clast) fraction increases they grade into pebbly
sandstones and then sandy conglomerates; where the fine-grained (mud) fraction in - creases they grade from muddy sandstones into sandy mudstones.
