lithificeerd

Lithified is the term used to describe the process by which loose sediment is transformed into solid rock. The word comes from lithos, the Greek for stone, and the suffix -ify, meaning to make or become. In geology, lithification is a key stage of diagenesis and marks the transition from unconsolidated sediment to sedimentary rock.

Lithification occurs mainly through two mechanisms: compaction and cementation. Compaction happens as sediments accumulate and overlying weight compresses the grains, reducing pore space and porosity. Cementation occurs when mineral-rich waters precipitate cementing materials such as calcite, quartz, or iron oxides in the spaces between grains, binding them together. The combined effects decrease porosity and increase strength, turning particles like sand, silt, or carbonate mud into sandstone, siltstone, shale, or limestone, among others. Lithification can also involve recrystallization or mineral replacement under diagenetic conditions.

Rocks formed by lithification include clastic sedimentary rocks (for example sandstone, siltstone, and shale) and chemical/biochemical carbonate rocks (such as limestone and dolostone). Coal is often described as lithified peat, formed when plant-rich material is buried and chemically altered under pressure and heat over long times.

Lithification typically occurs at shallow burial where temperatures are relatively low and groundwater circulates through sediments, over timescales of thousands to millions of years. It is distinguished from metamorphism, which alters rock under higher temperatures and pressures to form metamorphic rocks. Lithified rocks preserve the record of past environments and sedimentary processes within Earth’s crust.