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.
Rock fragments identify the source rocks.
Formed by precipitation. Most abundant chemical sedimentary rock. Those having a marine biochemical origin are the most common. Corral reefs - animals secrete a calcareous external skeleton. Australia's Great Barrier Reef.