lithifies

Lithifies is the third-person singular form of the verb lithify, used in geology to describe the process by which loose sediment becomes solid rock. Lithification is the broader set of diagenetic processes that consolidate sediment into sedimentary rock, typically through compaction, cementation, and, in some cases, chemical precipitation of minerals from pore waters.

Compaction occurs when sediments are buried under additional layers, increasing pressure and reducing porosity as grains are pressed together. Cementation involves minerals precipitating from groundwater and binding grains to form a cohesive rock. Common cements include calcite, silica (quartz or microcrystalline forms), and iron oxides, which can also influence color and strength. In carbonate-rich settings, lithification can involve cementation by calcite or the direct precipitation of carbonate minerals.

Timescales for lithification range from thousands to millions of years and depend on burial conditions, fluid chemistry, and rock type. The resulting rocks include clastic varieties such as sandstone, siltstone, and mudstone (formerly loose sediment compacted and cemented), as well as carbonate rocks like limestone and dolostone formed by cementation and mineral precipitation. The specific characteristics of a lithified rock reflect the original sediment and the nature of the mineral cement.

Lithification is a part of diagenesis, the suite of post-depositional changes that preserve the sedimentary record and convert loose sediments into stable sedimentary rocks. It is a low-temperature, shallow-process in contrast to metamorphism, which operates at higher temperatures and pressures.