Earth & Space Science: Weathering, Erosion, & Deposition

Comprehensive practice flashcards covering vocabulary for weathering, mass movement, erosion agents (wind, water, ice), and topographic map interpretation based on lecture notes.

Weathering

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

Mechanical weathering

The physical breakdown of rock into smaller pieces without changing its chemical composition or mineral identity.

Chemical weathering

The process that changes the mineral composition of rock through chemical reactions, forming new minerals.

Frost wedging

A mechanical weathering process where water seeps into cracks, freezes, and expands by approximately $9\%$ in volume, forcing the rock apart.

Abrasion

The physical wearing down of rock surfaces as particles grind against each other or bedrock, occurring in streams, glaciers, and wind environments.

Exfoliation

A type of mechanical weathering where rock expands and outer layers peel off in sheets as pressure from overlying material is released.

Root wedging

Mechanical weathering where plant roots grow into existing cracks and widen them as the plant grows.

Carbonation

A chemical weathering process where $CO_2$ dissolves in water to form weak carbonic acid, which reacts with and dissolves carbonate minerals like calcite and dolomite.

Oxidation

A chemical reaction where oxygen reacts with iron-bearing minerals to produce iron oxides (rust), often seen as reddish-brown staining.

Hydrolysis

A chemical weathering process where water reacts with silicate minerals, such as feldspar, breaking them down into clay minerals.

Karst

A landscape developed on soluble rock through dissolution, characterized by features such as caves and sinkholes.

Mass movement

The downslope movement of Earth materials driven by gravity, occurring when gravitational force exceeds the friction holding material in place.

Creep

The slow, continuous downslope movement of soil and regolith, visible through tilted fence posts and curved tree trunks.

Slump

Mass movement along a curved failure surface that causes a block of material to slide and rotate downslope.

Landslide

The rapid, sudden movement of large volumes of rock or sediment down a slope.

Undercutting

Erosion at the base of a slope, such as wave action on a coastal bluff, which removes support and triggers the sudden collapse of overhanging material.

Erosion

The removal and transport of weathered material away from its source by agents such as water, wind, ice, or gravity.

Deposition

The settling of sediment that occurs when a transporting agent loses energy and can no longer carry the material.

Sorting

The degree to which sediment particles are similar in size; water and wind produce well-sorted sediment, while glaciers produce poorly sorted mixtures.

Capacity

The total amount of sediment a stream can transport, which increases with water velocity.

Graded bedding

A sediment layer where grain size decreases upward from coarse to fine, representing a single depositional event where heavier particles settled first.

Gradient

The change in elevation over horizontal distance, calculated as $\text{Gradient} = \frac{\Delta \text{elevation}}{\text{horizontal distance}}$, which controls stream velocity.

Meander

A curve or bend in a river that develops on low-gradient floodplains where lateral erosion and deposition occur.

Cut bank

The outside of a river bend where water velocity is greatest, resulting in active erosion and a steep bank.

Point bar

The inside of a river bend where water velocity is lowest, resulting in the deposition of a gently sloping mound of sediment.

V-shaped valley

A narrow, steep-walled valley formed by the downcutting of high-gradient streams into bedrock.

Alluvial fan

A fan-shaped deposit of sediment formed where a high-gradient stream abruptly exits a narrow canyon onto a flat plain.

Delta

A triangular or fan-shaped deposit of sediment formed where a stream enters a standing body of water, such as a lake or ocean.

Ventifact

A rock shaped by wind abrasion, characterized by smooth, pitted, or faceted surfaces and a narrow base due to sand concentration near the ground.

Deflation

The process by which wind removes loose particles from a surface, lowering the land surface over time.

Striations

Parallel scratches and grooves carved into bedrock by rocks embedded in the base of a moving glacier, indicating the direction of ice movement.

U-shaped valley

A broad, flat-floored valley with steep walls carved by a glacier as it widens and deepens a pre-existing stream valley.

Till

Unsorted and angular sediment deposited directly by a glacier without water sorting.

Outwash

Well-sorted and rounded sediment deposited by meltwater streams flowing away from a glacier.

Moraine

A ridge of till deposited at or along the margins of a glacier; terminal moraines mark the farthest advance of the ice.

Drumlin

An elongated, streamlined hill of till shaped beneath a moving glacier, with a steep stoss end and a tapered lee end.

Erratic

A boulder or rock fragment transported far from its source by a glacier and deposited in a region with a different bedrock type.

Kettle lake

A bowl-shaped depression formed when a buried block of glacial ice melts, causing the overlying sediment to collapse.

Landscape

The physical shape of a region's surface resulting from the interaction of rock type, geologic structure, weathering, and erosion.

Relief

The difference in elevation between the highest and lowest points in a specific area.

Contour line

A line on a topographic map connecting all points that share the same elevation.

Contour interval

The vertical distance in elevation between adjacent contour lines on a topographic map.

Differential erosion

The unequal weathering and erosion of rocks with different levels of resistance, leading to varied landscape relief.