Earth Processes - Sedimentary Rocks and Soil Vocabulary

Vocabulary practice flashcards covering sedimentary rocks, weathering, depositional environments, sedimentary structures, soil formation, and soil profile horizons.

Mineral

A naturally occurring, solid, inorganic substance formed by geological processes, with a crystalline structure and a definable chemical composition.

Rock Cycle

The continuous geological process in which rocks transition between igneous, sedimentary, and metamorphic forms through melting, cooling, weathering, erosion, lithification, and heat and pressure.

Sedimentary Rock

A rock formed from deposits of pre-existing rocks or pieces of once-living organisms that accumulate on the Earth's surface and become compacted and cemented.

Source Area

The locality that eroded and provided sediment for a sedimentary rock, indicated by composition, shape, size, and sorting.

Depositional Environment

The location where sediment comes to rest, such as glacial valleys, river channels, floodplains, lakes, deltas, beaches, dunes, or marine basins.

Detrital (Clastic) Rocks

Sedimentary rocks produced from accumulated rock fragments and mineral particles derived from pre-existing rocks.

Chemical Sedimentary Rocks

Sedimentary rocks produced by the chemical precipitation of dissolved ions in water.

Organic Sedimentary Rocks

Sedimentary rocks produced by the accumulation of biological debris, such as plant remains in swamps or bogs.

Conglomerate

A clastic sedimentary rock composed of rounded fragments of gravel, cobbles, or boulders embedded in sand, silt, and/or clay.

Breccia

A clastic sedimentary rock composed of angular fragments embedded in sand, silt, and/or clay.

Sandstone

A clastic sedimentary rock composed of sand grains measuring $0.006\,cm$ to $0.2\,cm$.

Siltstone

A clastic sedimentary rock composed of very fine silt particles measuring $0.0004\,cm$ to $0.006\,cm$.

Shale

A compact clastic sedimentary rock made of clay particles smaller than $0.0004\,cm$ that splits easily into thin sheets.

Rock Salt

A crystalline chemical sedimentary rock composed of halite, formed as chemical precipitates and evaporites.

Limestone

A crystalline or bioclastic sedimentary rock composed of calcite, formed from biologic precipitates or cemented shell fragments.

Bituminous Coal

A bioclastic sedimentary rock formed from compacted plant remains and composed mostly of carbon.

Weathering

The breakdown of rocks at or near the Earth's surface into smaller pieces through physical fragmentation or chemical alteration.

Erosion

The physical removal and transportation of weathered rock material by a mobile agent such as water, wind, or ice.

Frost Wedging

A physical weathering process where water enters cracks in rocks, freezes, expands, and wedge-pries the rock apart.

Bowen's Reaction Series

A sequence showing that minerals crystallizing early at high temperatures (e.g., olivine) weather fastest at Earth's surface, while late-forming minerals (e.g., quartz) are most stable.

Transportation

The movement of sediment away from its source by water, wind, or ice, leading to rounding by abrasion and sorting by grain size.

Deposition

The settling of transported sediment or accumulation of chemical/organic material in a basin.

Lithification

The combination of compaction and cementation processes that transform loose sediment into solid sedimentary rock.

Ripple Marks

Small ridges formed on the surface of a sediment layer by the action of moving wind or water.

Graded Bedding

A sedimentary structure featuring a progressive change in grain size from coarse at the bottom to fine at the top of a single bed.

Mud Cracks

Polygonal crack patterns formed when mud contracts as it dries.

Bedding

A series of visible horizontal layers within sedimentary rock, representing the most common sedimentary structure.

Cross-Bedding

A sedimentary structure consisting of thin, inclined layers within a horizontal bed of rock, indicative of deposition in dunes, ripples, bars, or deltas.

Soil

A natural surface mixture composed of $45\%$ mineral matter, $25\%$ air, $25\%$ water, and $5\%$ organic matter.

Residual Soil

Soil that develops directly in place from the weathering of the underlying bedrock parent material.

Transported Soil

Soil that develops on loose, unconsolidated sediment deposits that have been carried from elsewhere.

Solum

The 'true soil' comprising the active O, A, E, and B horizons where plant roots and organic matter are concentrated.

O Horizon

The uppermost soil layer consisting of loose and partly decayed organic matter.

A Horizon

The topsoil horizon made of mineral matter mixed with humus.

E Horizon

The soil horizon characterized by eluviation and leaching of soluble materials.

B Horizon

The subsoil layer where fine clay particles leached from upper horizons accumulate.

C Horizon

The soil horizon consisting of partially altered parent bedrock or unconsolidated material.

Kaolinite

A clay mineral ($Al_2Si_2O_5(OH)_4$) produced by the chemical weathering of K-feldspar, forming a major mineral export of Georgia.