Pertaining to a river or stream. A fluvial sandstone is a sandstone that was deposited in a river.

Folks classification of limestones based on the matrix/cement and the main lithological components. For example, a limestone with a micrite matrix containing mainly ooids would be Oomicrite. If the cement were sparite instead, then it would be an Oosparite. Folk used four main clast types: ooids, bioclast, peeloid and intraclast.

A formation is a group of beds used in stratigraphy. This is the smallest unit on a geological map. Formations are grouped together into a group. See also Member.

A sediment grain with a diameter of 2-20mm

A grouping of formations used in stratigraphy.

A rock composed mainly of calcium carbonate CaCO₃. Limestones comprise a large variety of rocks including carbonate muds and oozes, chalks, ooliths and bioclastic limestone. They form in a variety of environments from deep sea (but above the carbonate compensation depth), temperate seas, tropical sea, lakes and rivers. Most caves are found in limestones due to erosion by acidic water. Limestones erode into karst topography.

The process of turning loose sediment into a sedimentary rock. This is done by heat, pressure and time. This process can take from years to millions of years. Hardgrounds are formed in inter-tidal carbonates and can form in years. Usually this process is a slow one. If this process continues, metamorphism occurs.

A division of a formation, generally of distinct lithologic character and of only local extent.

Micro-crystalline carbonate mud.

A spherical grain of calcium carbonate, either aragonite or calcite. See the Ooid Formation tutorial for more details of their formation and origin.