Chapter 13:Weathering, Karst Landscapes & M.

Geography 203 with Heyman at Texas A&M University

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By: Raul Garcia
Created: 2012-05-05
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Geomorphology

The science that analyses and describes the origin, evolution, form, classification, and spatial distribution of landforms.

Denudation

A general term that refers to all processes that cause degradation of the landscape: weathering/water, mass movement, erosion and transport.

Differential Weathering

The effect of different resistances in rock, coupled with variations in the intensity of physical and chemical weathering.

Dynamic Equilibrium Model

The balancing act between tectonic uplift and erosion between the resistance of crust materials and the work of denudation processes. Landscapes evidence ongoing adaptation to rock structure, climate, local relief, and elevation.

Geomorphic Threshold

The threshold up to which landforms change before lurching to a new set of relationships, with rapid realignments of landscape materials and slopes.

Slopes

A curved, inclined surface that bounds a landform.

Weathering

The process by which surface and subsurface rocks, disintegrate, or dissolve, or are broken down. Rocks at or near Earth's surface are exposed to physical and chemical weathering processes.

Bedrock

The rock of Earth's crust that is below the soil and is basically unweathered; such solid crust sometimes is exposed as an outcrop.

Sediment

Fine grained mineral matter that is transported and deposited by air, water or ice.

Parent Material

The unconsolidated material, from both organic and mineral sources, that is the basis of soil development.

Rock Composition and Structure (jointing)

Jointing is important for weathering processes.

Joints

Fractures or separations in rock that occur without displacement of the sides. The presence of these usually flat spaces increases the surface area of rocks exposed to both physical and chemical weathering.

Climate

Precipitation, temperature, and freeze-thaw cycles are the most important factors affecting weathering.

Subsurface Water

Influencing weathering processes include both the position of the water table and water movement within soil and rock structures.

Slope Orientation

The geographical orientation of a slope --whether it faces north, south, east, or west -- controls the slope's exposure to Sun, wind, and precipitation; especially noticeable in the middle and higher latitudes.

Vegetation

Although vegetation cover can protect rock by shielding it from raindrop impact and providing roots to stabilize soil, it also produces organic acids from the partial decay of organic matter; these acids contribute to chemical weathering,

Physical Weathering (Mechanical Weathering)

The breaking up and disintegration of rock without any chemical alteration.

Frost Action

A powerful mechanical force produced as water expands up to 9% of its volume as it freezes. Water freezing in a cavity in a rock can break the rock if it exceeds the rock's tensional strength

Sheeting

A form of weathering associated with fracturing or fragmentation of rock by pressure release; often related to exfoliation processes.

Exfoliation Dome

A dome-shaped feature of weathering, produced by the response of granite tot the overburden removal process, which relieves pressure from the rock. Layers of rock slough off in slabs or wheels in a sheeting process.

Chemical Weathering

Decomposition and decay of the constituent minerals in rock through chemical alterations of those minerals. Water is essential, with rates keyed to temperature and precipitation values. Chemical reactions are active at microsites even in dry climates. Processes include hydrolysis, oxidation, carbonation, and solution.

Spheroidal Weathering

A chemical weathering process in which the sharp edges and corners of boulders and rocks are weathered in think plates that create a rounded, spheroidal form.

Hydration

A chemical weathering process involving water that is added to a mineral, which initiates swelling and stress within the rock, mechanically forcing grains apart as the constituents expand.

Hydrolysis

A chemical weathering process in which minerals chemically combine wit water; a decomposition process that causes silicate minerals in rocks to break down and become altered.

Oxidation

A chemical weathering process in which oxygen dissolved in water oxides (combines with) certain metallic elements to form oxides; most familiar is the "rusting'" of iron in rock or solid (Ultisols, Oxisols), which produces a reddish-brown stain of iron oxide.

Carbonation

A chemical weathering process in which weak carbonic acid (water/carbon dioxide) reacts with many minerals that contain calcium, magnesium, potassium & sodium (especially limestone) transforming them into carbonates.

Karst Topography

Distinctive topography formed in a region of chemically weathered limestone with poorly developed surface drainage and solution features that appear pitted and bumpy, originally namede after the Krs Plateau in Slovenia.

Sinkholes

Nearly circular depression created by the weathering of karst landscapes with subterranean drainage; also known as a doline in traditional studies; may collapse through the roof of an underground space.

Mass Movement

All unit movements of materials propelled by gravity; can range from dry to wet, slow to fast, small to large, and free falling to gradual or intermittent.

Mass Wasting

Gravitational movement of nonunified material downslope; a specific form of mass moving.

Angle of Response

The steepness of a slope that results when loose particles come to rest; an angle of balance between driving and resisting forces ranging between 33 degrees and 37 degrees from a horizontal plane.

Rockfall

Free-falling movement of debris from a cliff or steep slope, generally falling straight or bounding downslope.

Talus Slope

Formed by angular rock fragments that cascade down a slope along the base of a mountain, poorly sorted, cone-shaped deposits.

Debris Avalanche

A mass of falling and tumbling rock, debris, and soil; can be dangerous because of the tremendous velocities achieved by the onrushing materials.

Landslide

A sudden rapid downslope movement of a cohesive mass of regolith and/or bedrock in a variety of mass movement forms under the influence of gravity; a form of mass movement.

Mudflows

Fluid downslope flows of material containing more water than earth flows.

Soil Creep

A persistent mass movement of surface soil where individual soil particles are lifted and disturbed by the expansion of soil moisture as it freezes or by grazing livestock or digging animals

Scarification

Human-induced mass movements of Earth materials, such as large scale open pit mining and strip mining.

About this deck

By: Raul Garcia
Created: 2012-05-05
Size: 38 flashcards
Views: 49

About StudyBlue

“I have been getting MUCH better grades on all my tests for school. Flash cards, notes, and quizzes are great on here. Thanks!”
Kathy