Geology Chapter 6: Sedimentary Rocks & Mass Wasting

A comprehensive collection of vocabulary flashcards covering sedimentary rock formation, classification, and mass wasting mechanisms from Geology Chapter 6.

Sedimentary Rock

The most common rock type found at Earth's surface.

Parent Rock

The original rock from which sediment forms.

Four Formation Steps of Sedimentary Rocks

The sequential four steps of rock formation: weathering, erosion, deposition, and lithification.

Weathering

The breakdown or alteration of rock at or near Earth's surface.

Physical Weathering

The mechanical breaking of rock without changing its chemical composition.

Chemical Weathering

Weathering caused by chemical reactions that alter and change minerals in rock.

Carbonic Acid

A weak acid formed when $\text{CO}_2$ dissolves in water that helps chemically weather rock.

Saprolite

Soft, intensely chemically weathered rock that stays in place and retains some of its original structure.

Erosion

The movement of sediment, which requires energy and uses agents such as water, wind, ice, and gravity.

Deposition

The process where sediment settles or drops, usually occurring when the transport medium loses energy.

Basin

A low area that collects sediment.

Accommodation Space

The available room in a basin for sediment to accumulate.

Subsidence

The sinking of land, which creates more accommodation space for sediment.

Stratum (Bed)

A single layer of sedimentary rock.

Strata

Multiple layers of sedimentary rock preserving Earth's history.

Lithification

The process through which loose sediment becomes solid rock.

Compaction

The lithification step where sediment grains are squeezed together.

Cementation

The lithification step where sediment grains are glued together by precipitated minerals.

Clastic Sediment

Sediment composed of broken rock or mineral pieces.

Clast

A single fragment or broken piece of rock or mineral.

Sorting

A description of the similarity in grain size within clastic sediment, categorized as well sorted (similar sizes) or poorly sorted (mixed sizes).

Rounding

The degree of grain-edge smoothness in clastic sediment, ranging from angular to subangular, subrounded, and rounded.

Chemical Sediment

Sediment composed of material that precipitates out of water.

Dissolution

The process in which a mineral dissolves into liquid.

Precipitation

The process in which dissolved material crystallizes and becomes solid.

Halite

A mineral with the chemical formula $\text{NaCl}$ that forms rock salt.

Chert

A hard sedimentary rock made of microscopic quartz.

Biogenic Sediment

Sediment derived from the remains or activities of living organisms.

Chalk

A soft limestone formed from microscopic calcium-carbonate remains.

Limestone

A sedimentary rock made mainly of calcium carbonate or calcite, often formed from biological shells.

Coal

A carbon-rich biogenic sedimentary rock made from accumulated and altered plant material.

Mass Wasting

The gravity-driven downhill movement of rock, soil, or sediment.

Angle of Repose

The steepest stable angle for loose material, which is approximately $35^\circ$.

Rockslide

A relatively rapid mass-wasting event involving sliding rock.

Creep

An extremely slow mass-wasting movement of soil or sediment, often indicated by tilted trees, poles, fences, or structures.

Risk Assessment Maps

Maps used to identify areas susceptible to mass wasting and guide land development.

Drainage Control

A method of mass wasting prevention that removes or redirects excess water to improve slope stability.

Retaining Walls

Structures built to hold soil, rock, or sediment in place on a slope.

Rock Bolts

Fasteners used to anchor unstable rock to stable underlying rock.

Thistle, Utah (1983)

Site of a $1983$ landslide that caused approximately $\$200\text{ million}$ in damage, which notes state could have been prevented with approximately $\$500{,}000$ in drainage control.