Sedimentary Rocks

Sedimentary Rocks

Rocks formed by the accumulation and consolidation of sediments.

Diagenesis

All of the chemical, physical, and biological changes that take place after sediments are deposited.

Lithification

The process by which unconsolidated sediments are transformed into solid sedimentary rock.

Clastic Rocks

Sedimentary rocks composed of fragments of pre-existing rocks.

Chemically Precipitated Rocks

Rocks formed from the precipitation of minerals from a solution.

Gravel

Sedimentary material composed of large particles such as boulders, cobbles, pebbles, granules.

Shale

A common sedimentary rock that consists of mud-sized particles in thin layers.

Sandstone

A sedimentary rock composed of sand-sized particles.

Conglomerate

A coarse-grained sedimentary rock composed mainly of rounded gravels.

Breccia

A coarse-grained sedimentary rock composed mainly of sharp, angular particles.

Limestone

The most abundant chemical rock, primarily composed of calcite.

Dolostone

A rock formed secondarily from limestone, primarily composed of magnesium carbonate.

Chert

A sedimentary rock made of microcrystalline quartz.

Evaporites

Sedimentary rocks formed from the evaporation of water, resulting in precipitated minerals.

Coal

A sedimentary rock composed primarily of organic material from plant remains.

Oil Trap

A geologic environment that allows significant amounts of oil and gas to accumulate.

Porous Reservoir Rock

A rock that is permeable and allows oil and gas to flow through it.

Cap Rock

An impermeable layer that prevents oil and gas from escaping.

Environment of Deposition

A geographic setting where sediment is accumulating.

Clastic Texture

Texture associated with rocks composed of discrete fragments and particles.

Nonclastic Texture

Texture associated with rocks that have interlocking crystals.

Fossil Fuels

Natural resources such as coal, oil, and natural gas that are derived from organic materials.

Compaction

The process by which sediments are squeezed together under pressure.

Cementation

The process of binding sediment particles together with minerals.

Mechanical Weathering

Breaking down rocks into smaller pieces without changing their chemical composition.

Chemical Weathering

Breaking down rocks through chemical reactions.

Quartz

A hard, crystalline mineral composed of silicon and oxygen.

Feldspar

A group of minerals that are common in igneous and sedimentary rocks.

Micas

A group of silicate minerals known for their sheet-like crystal structure.

Grain Size

The diameter of individual particles or crystals in a sedimentary rock.

Peat

An accumulation of partially decayed organic matter, a precursor to coal.

Lignite

A type of coal that is brownish-black and has low heat value.

Bituminous Coal

The most common coal used for energy, typically black and shiny.

Anthracite

A high-grade coal known for its high carbon content and low pollution.

Trilobite

An extinct marine arthropod commonly found as a fossil in sedimentary rocks.

Biodiversity

The variety of life in a particular habitat or ecosystem, often indicated by fossils.

Sediment Transport

The movement of solid particles through fluids such as air or water.

Marine Environments

Areas of the ocean including shallow and deep waters where sediment can accumulate.

Transitional Environments

Areas such as shorelines where both marine and terrestrial processes influence sediment deposition.

Glacial Environment

A cold environment characterized by the movement of glaciers that transport and deposit sediments.

Colian Environment

A desert environment where wind is the primary force of sediment transport.

Tidal Flats

Coastal areas that are covered and uncovered by tides, often rich in sediments.

Deltas

Landforms created at the mouths of rivers where sediments are deposited as the water flows into a larger body of water.

Permeability

The ability of a material to transmit fluids through its pore spaces.

Chemical Rock

A type of sedimentary rock that forms from the precipitation of minerals from water.

Organic Processes

Processes involving the decomposition of organic matter that lead to the formation of certain sedimentary rocks.

Inorganic Processes

Processes that do not involve organic materials, often relating to chemical deposition.

Acid Test

A test used to identify certain minerals (like calcite) by observing whether they react with acid.

Geologic Time

A time scale used to describe the timing and relationships between events that have occurred throughout Earth's history.

Environment of Formation

The specific geological conditions under which a rock is formed.

Natural Gas

A fossil fuel derived from the remains of marine organisms, often found alongside oil.

Carbonate Minerals

Minerals that contain carbonate ion (CO3), including calcite and dolomite.

Gypsum

A soft sulfate mineral used in fertilizer and for producing plaster.