All the changes that take place in a sediment at low temperature and pressure after deposition. With increasing temperature and pressure, diagenesis grades into metamorphism. Diagenetic processes such as compaction, dissolution (see pressure solution), cementation, replacement, and recrystallization are the means by which an unconsolidated, loose sediment is turned into a sedimentary rock, e.g. sand into a sandstone, or peat into coal. See also carbon isotopes; oxygen isotopes.