Due to their continuing deposition and widespread distribution, sedimentary rocks hold many clues to the geologic past and to past environmental conditions on earth.
Particles tend to form in thin laminae.
Compaction aligns clay particles. Splits easily along parallel, closely spaced planes - fissility. Mudstone Similar to shale except no fissility - rock breaks into chunks. Sandstone Forms in a variety of environments - beaches, dunes, offshore continental margins. Generally poorly sorted.