Ch. 03 Flashcards
The process by which land areas are reduced and shaped through weathering and erosion.
Denudation
The breakdown of minerals into new compounds through chemical agents such as acids in the air, rain, and river water.
Chemical Weathering
The breakdown of rocks into smaller particles through temperature changes, impact from raindrops, and abrasion from wind-carried mineral particles.
Mechanical Weathering
Mechanical and chemical changes to the ground caused by the activities of plants, animals, and microbial action.
Biological Weathering
The process of removing weathered material (detritus) from its source area by agents like rivers, wind, moving ice, and water waves.
Erosion
The laying down of transported detritus to form features such as deltas, beaches, screes, and sand dunes.
Deposition
What are the (7) Chemical Weathering Processes
Solution
Oxidation
Reduction
Hydration
Hydrolysis
Leaching
Cation Exchange
A vertical sequence of layers from topsoil to unweathered rock, consisting of A-horizon (soil), B-horizon (sub-soil), and C-horizon (unweathered rock).
Soil Profile
Landforms resulting from chemical weathering of limestone, characterized by caves, sinkholes, and underground drainage systems.
Karst Topography
Formations in caves resulting from the deposition of calcium carbonate due to evaporation of water charged with calcium bicarbonate.
Stalactites and Stalagmites
Upstanding masses of solid granite preserved due to wider spacing of joints, contrasting with adjacent rocks more extensively denuded by weathering.
Granite Tors
Describe Weathering in Different Climates
Wet climates: Deep weathering due to vegetation, heavy rainfall.
Dry climates: Superficial weathering, mechanical processes dominant.
Weathering Agents
Rainwater
Frost
Wind
Temperature changes
Abrasion from mineral particles
Biological activity (plants, animals, microbes)
Types of Weathering
Physical and Chemical
Factors Influencing Weathering Rates
Presence of water
Climate (wet vs. dry)
Presence of vegetation
Type of rock and minerals present
Temperature variations
Signs of Chemical Weathering
Formation of solution hollows on limestone surfaces
Widening of vertical joints in rocks due to solution
Formation of swallow holes and underground caverns in limestone areas
Development of karst topography features like sinkholes and disappearing streams
Role of Vegetation in Weathering
Production of CO2 in the root zone, enhancing chemical weathering
Roots penetrating rocks, breaking them apart
Increased acidity of soil due to root activity, aiding chemical reactions
Effects of Weathering on Soil
Formation of soil horizons (A-horizon, B-horizon, C-horizon)
Porosity and compressibility of soil
Nutrient content and organic matter accumulation
Examples of Landforms Created by Weathering and Erosion
River valleys and canyons
Coastal cliffs and sea stacks
Glacial valleys and moraines
Alluvial plains and floodplains
Human Impacts on Weathering and Erosion:
Deforestation leading to increased erosion rates
Urbanization altering natural drainage patterns
Agriculture practices affecting soil erosion
Climate change influencing weathering rates and erosion patterns
Mechanical Weathering Processes
Unloading
Loading
Thermal Loading
Wetting and Drying
Crystallization
Pneumatic Loading
Reduction of vertical load by erosion, leading to vertical expansion and the formation of sheet-like rock structures.
Commonly observed in igneous rocks like granite, resulting in sheet-jointing.
Unloading
Repeated freezing and thawing of water in pores and fractures of rocks.
Frost Action
Permanently frozen ground, prevalent in cold climates, especially within the Arctic Circle.
Permafrost
Shallow zone thawing annually during milder seasons.
Active layer
Slow movement of surface material over frozen ground due to repeated freezing and thawing.
Solifluction
Formation of segregated ice layers at shallow depths in soil.
Frost-Heaving
Weathering process in hot climates, involving the expansion and contraction of rocks due to temperature changes.
Insolation
Outer layers of rock pull away from cooler layers, resulting in flake and slab detachment.
Exfoliation
Weathering effects attributed to plants and animals.
Biotic Weathering
Roots of plants penetrate cracks in rocks, wedging apart crack walls and hastening mechanical break-up.
Mechanical Break-up by Plants
Relationship Between Soils and Weathering
Soils are classified according to climatic zones, reflecting latitude.
Soils and weathering processes exhibit a basic relationship influenced by climate.
Found in South America, Central and Southern Africa, India, Sri Lanka, Southeast Asia, East Indies, and Australia.
Rich in aluminum and iron oxides, formed under previous climatic conditions.
Laterite Deposits
what are agents of erosion?
Rivers, wind, moving ice, and water waves
Agents of transport, carrying material in suspension and re-depositing downstream, forming levees and flood plains.
River Erosion
Zig-zag courses with overlapping spurs
Youthful Valleys
occurs when a river’s cutting power is revived
Rejuvenation
Break in slope at the junction of old and new river courses.
Nick-point
Erosion in alternating hard and soft rock layers results in ________
Terraced Slopes
Flat-topped hill with a hard rock cap.
Mesa
These form where rivers flow over rocks of differing hardness.
Waterfalls and Rapids
between Lake Erie and Lake Ontario, drops 55 meters over hard limestone.
Niagara Falls
formed by youthful streams eroding rapidly.
Gorges
The Colorado River carved _________ over 400 km in length and about 2 km deep.
Grand Canyon
occurs as rivers swing from side to side
Meandering Rivers
Meandering rivers can create _________ when loops are cut off during floods.
Oxbow Lakes
Meanders can become ________ when rivers gain fresh energy and downcut.
Incised Meanders
Deposits laid down by rivers, including fine materials like silt and mud, and coarser sand and gravel.
Alluvium
form where rivers enter bodies of water and deposit sediment.
Deltas
occurs on the land margin through their impact and the debris they carry, especially during storms
Wave erosion
the interface between the land and water
coastal zone
caused by the pull of the sun and moon, create periodic rises and falls in the sea level.
tides
tides that occur during full and new moons
spring tides
tides that occur during the moon’s first and third quarters.
neap tides
generated in shallow seas and channels due to the rise and fall of tides.
tidal currents
quick water movements, occur during severe storms, causing extensive flooding and damage along coastlines.
tidal surges
generated by wind sweeping across the water surface.
waves
Waves _______ as they run into shallow water, causing erosion and forming the means of wave action.
break
the process by which local sea level rise, strong wave action, and coastal flooding wear down or carry away rocks, soils, and/or sands along the coast.
coastal erosion
Resulting from a rise in sea level relative to the land, creating features like headlands and cliffs by erosion.
Submergence Coastline
Sediments sorted by waves and currents, contributing to shallow-water deposits along coasts.
Coastal Marine Deposits
Movement of sediment along the shoreline due to incoming waves and backwash.
Littoral Drift
Sandy ridges extending into open water from bends in the coast, formed by longshore drift.
Spits
Compound spits gradually building out to sea, shaping prominent coastlines.
Cuspate Forelands
Spits extending across bays, forming barriers with lagoons behind them.
Barriers
Areas behind bay-bars silted up with river-transported sediment, forming mud flats between low and high water levels.
Mud Flats
Formed by calcium carbonate-secreting organisms in warm, shallow waters, taking the form of barriers, fringe reefs, or atolls.
Coral Reefs
Resulting from a rise in the land relative to the sea, creating a smooth coastline as sea floor is exposed.
Emergence Coastline
The area of the shore between the high tide and low tide marks, often characterized by diverse marine life.
Littoral Zone
The process by which rocks and sediment are worn away by natural elements like waves, wind, and ice.
Erosion
The process by which eroded materials are dropped or settled in a new location, contributing to coastal formations.
Deposition
Currents that flow parallel to the shoreline, influencing the movement of sediment along the coast.
Longshore Currents
A geological landform consisting of a steep and often vertical column of rock in the sea near a coast, formed by erosion.
Sea Stack
A flat, horizontal surface formed by the erosion of waves at the base of a cliff, often visible at low tide.
Wave-cut Platform
The gradual movement of a cliff face inland due to erosion, typically driven by wave action.
Cliff Retreat
The bending of waves as they approach a coastline, resulting in the concentration of wave energy on headlands.
Wave Refraction
The process of adding sand or other sediment to a beach to counteract erosion and maintain its size and shape.
Beach Nourishment
A strong, narrow current flowing outward from the shore, typically perpendicular to the shoreline, posing a hazard to swimmers.
Rip Current
A partially enclosed coastal body of brackish water where freshwater from rivers and streams meets and mixes with seawater.
Estuary
Sediments deposited in the open ocean, including clay, sand, and volcanic dust.
Pelagic Sediments
Pelagic sediment composed primarily of calcium carbonate derived from the skeletons of marine organisms.
Calcareous Ooze
Pelagic sediment composed primarily of silica, formed from the skeletons of diatoms and radiolarians.
Siliceous Ooze
The depth at which the rate of supply of calcium carbonate is balanced by its rate of dissolution in seawater.
Calcite Compensation Depth
Distinctive deep-sea sediment formed from volcanic and wind-derived material.
Red Clay
Subsurface currents in the ocean that transport sediments and shape the ocean floor.
Deep Ocean Currents
Prevailing winds that circulate around the Earth due to differences in solar energy absorption.
Global Winds
The process by which wind transports and erodes soil and rock particles.
Wind Erosion
Sand transported and deposited by wind, often characterized by rounded grains and well-sorted sizes.
Eolian Sand
Fine, silty sediment deposited by wind, often forming extensive deposits in certain regions.
Loess
Large pebbles or boulders in desert environments that have been faceted and smoothed by wind-blown sand.
Dreikanters
Residual peaks of hard rock that rise abruptly from a surrounding plain due to erosion of softer rock layers.
Inselbergs
The region of the central United States, particularly Kansas and Nebraska, affected by severe soil erosion and dust storms during the 1930s.
Dust Bowl
The process by which soil is removed from the land surface by wind, water, or other natural forces.
Soil Erosion
A gently sloping erosion surface found in arid regions, often adjacent to inselbergs.
Pediment
The process by which fertile land becomes desert, typically as a result of drought, deforestation, or inappropriate agriculture practices.
Desertification
Atmospheric phenomena characterized by strong winds carrying large quantities of dust particles over vast areas.
Dust Storms
Physical characteristics of landscapes resulting from the wearing away of rock and soil by wind, water, or other erosive forces.
Erosional Features
Rock formed from the accumulation and lithification of sediment, including sandstone, shale, and limestone.
Sedimentary Rock
The process by which wind removes loose surface material, such as sand and soil, from the ground.
Deflation
The movement of sand grains in a series of short jumps or bounces along the ground, driven by wind or water.
Saltation
Geomorphic processes involving the transport and deposition of sediment by wind.
Aeolian Processes
A rock that has been shaped and polished by wind abrasion, often characterized by smooth surfaces and faceted edges.
Ventifact
The mechanical wearing away of rock surfaces by the impact of sediment particles carried by wind or water.
Abrasion
Small-scale sedimentary structures formed on the surface of sand or silt by the action of wind or water currents.
Ripple Marks
Fine particles of sand and dust lifted from the Sahara Desert and transported across long distances by atmospheric currents.
Saharan Dust
The movement of sand dunes across the landscape due to the action of wind, typically in the direction of prevailing winds.
Sand Dune Migration
A sedimentary structure formed by the inclined layers of sediment within a larger sedimentary unit, often seen in sandstone and indicative of past wind or water currents.
Cross-bedding
A surface layer of closely packed pebbles and small stones, formed by the removal of finer material by wind erosion.
Desert Pavement
A crescent-shaped sand dune with its tips pointing downwind, formed by the action of wind in areas with limited sand supply.
Barchan Dune
Large accumulations of sand covering vast areas in desert regions, such as the Sand Sea of the Egyptian Desert.
Sand Sheets
Mounds of blown sand formed along coastal regions due to prevailing winds, often found in temperate climates.
Coastal Sand Hills
A type of grass commonly used to stabilize coastal dunes by binding the surface layers of sand with its long roots.
Marram Grass (Ammophila arenaria)
The largest forms of desert dunes, characterized by long ridges similar in shape to a long, low rounded hill, least susceptible to major change.
draa
Long ridges of coarse sand found in desert regions, extending for great distances and built by gentle winds bringing in sand supplies.
Seif Dunes
The inclined surface along which sand on the leeward slope of a dune shears away due to exceeding the angle of repose.
Slip-surface
Layers of sandstone formed in past geological ages, preserving the orientation of dunes and reflecting the prevailing wind direction of the desert at that time.
Ancient Dune-bedding
Material carried by glaciers and deposited along their margins or within their bodies.
Moraine
Classifications of Moraine
Lateral, medial, terminal
Rock debris and other sediment carried within the body of a glacier. This material can include rocks plucked from the valley floor and sides as well as loose surface debris.
Englacial Material
As glaciers move over land surfaces, they erode the underlying rocks, smoothing the bedrock and creating distinctive landforms such as grooves, striae, and cirques.
Glacial Erosion
Rounded rock formations created by the shearing action of glaciers on bedrock obstacles. These formations often have a smooth, rounded side facing the direction of glacier movement and a steep, plucked side facing away from the glacier.
Roches Moutonnées
Bowl-shaped depressions excavated by glaciers at the head of valleys, typically formed through the process of plucking and abrasion.
Cirques or Corries
Valleys that have been widened and deepened by the erosive action of glaciers
U-shaped Valleys
Lake basins that have been excavated to great depths below sea level by glacial erosion.
Over-deepened Basins
Flat, fertile plains formed by the deposition and reworking of glacial sediments by meandering rivers, typically found at the upper levels of glaciated valleys where the U-shaped profile is obscured by deposited material.
Alluvial Plains
