Introduction to Sedimentary Rocks and Processes

Vocabulary practice cards covering sedimentary rock classifications, formation mechanisms, transport environments, and sequence stratigraphy from the Chapter 1 lecture notes.

Sedimentary Rock

A type of rock created when sediments derived from pre-existing rocks or chemical solutions undergo compaction, cementation, and lithification.

Lithification

The process of turning unconsolidated sediments into solid rock through compaction under pressure and cementation by precipitating minerals.

Detrital Sediments

Solid, physical particles such as gravel, sand, and silt produced by the mechanical weathering and grinding down of pre-existing rocks.

Chemical Sediments

Sediments formed when dissolved ions in a liquid solution precipitate out to form mineral crystals.

Organic Sediments

Sediments formed from the accumulation and consolidation of plant matter, fossils, or organic debris over time.

Breccia

A coarse-grained detrital sedimentary rock with angular clasts, indicating deposit near its source in a high-energy environment like a landslide.

Conglomerate

A coarse-grained detrital sedimentary rock composed of rounded clasts, indicating high-energy transport over long distances in river environments.

Sandstone

A medium-grained detrital sedimentary rock composed of grains less than $1\,\text{mm}$ in size, commonly deposited in moderate-energy environments like beaches or dunes.

Arkose

A variety of sandstone containing a significant proportion of feldspar minerals alongside quartz grains.

Graywacke

A category of sandstone characterized by a matrix rich in clay and fine-grained materials.

Shale

A very fine-grained detrital sedimentary rock made of particles smaller than $\frac{1}{60}\,\text{mm}$ that exhibits distinct flat laminations and forms in low-energy environments.

Limestone

A chemical sedimentary rock primarily composed of calcium carbonate ($\text{CaCO}_3$) in the form of calcite, often formed from marine organism shells or direct seawater precipitation.

Chert

A crypto-crystalline chemical sedimentary rock composed almost entirely of silica oxide, precipitated in oceans by organisms like diatoms.

Evaporites

Chemical sedimentary rocks (such as gypsum and halite) that form when a mineral-rich liquid solution or brine evaporates and leaves dissolved elements behind.

Halite

A naturally occurring rock-forming salt crystal deposited as an evaporite sedimentary rock.

Gypsum

A very soft calcium sulfide evaporite mineral that can be dehydrated by heating to create plaster of Paris.

Peat

An accumulation of partially decayed organic vegetation formed in marshy environments, representing the initial precursor stage of coal formation.

Anthracite

A dark, shiny black, high-grade coal formed when organic material undergoes extreme heat and pressure to remove volatiles.

Oil Shale

An organic-rich sedimentary rock formed in low-energy marine settings from accumulated organic matter like plankton and seaweed, which yields petroleum when heated.

Cross-Bedding

Inclined layering structure within sandstones formed by wind or water currents, where the upward-pointing ramps indicate the opposite direction of fluid flow.

Marine Transgression

A relative rise in sea level that causes shorelines to migrate landward, producing a vertical rock sequence where fine-grained deep-water sediments overlay coarse-grained shallow-water sediments.

Marine Regression

A relative drop in sea level that causes shorelines to shift basinward, resulting in shallow-water sediments depositing on top of deep-water sedimentary layers.