Solution Processes and Solution Processes and Karst TopographyKarst Topography

Chapter 17Chapter 17

Solution Processes and Karst Solution Processes and Karst TopographyTopography

Solution and PrecipitationSolution and Precipitation Caverns and Related FeaturesCaverns and Related Features Karst TopographyKarst Topography Hydrothermal FeaturesHydrothermal Features

Relative Solubility in WaterRelative Solubility in Water

This diagram This diagram demonstrates the demonstrates the solubility of solubility of common rock common rock forming elementsforming elements

Sodium and Sodium and calcium are very calcium are very soluble soluble

Aluminum is NOTAluminum is NOT

CavernsCaverns

Large caves or chambers in cavesLarge caves or chambers in caves Found anywhere there’s a massive Found anywhere there’s a massive

limestone deposit at/near the surfacelimestone deposit at/near the surface Usually larger horizontally than verticallyUsually larger horizontally than vertically Connection to surface can small or hiddenConnection to surface can small or hidden Can be very extensive system of “rooms”Can be very extensive system of “rooms” Stream may flow along floorStream may flow along floor

Cavern FormationCavern Formation Solution of underground water trickles Solution of underground water trickles

along bedding planes and joint systemsalong bedding planes and joint systems Water dissolves limestone bedrock and Water dissolves limestone bedrock and

leaves holesleaves holes Water leaves behind compounds it carried Water leaves behind compounds it carried

in solutionin solution

Cavern FeaturesCavern Features Water dripping from roof forms Water dripping from roof forms

stalactitestalactite – icicle – icicle Water hits floor and builds upward - Water hits floor and builds upward -

stalagmitestalagmite

Karst TopographyKarst Topography

Karst LandformsKarst Landforms– SinkholeSinkhole– Tower KarstTower Karst

Karst TopographyKarst Topography

Limestone and Karst RegionsLimestone and Karst Regions

Development Development of Karst of Karst

TopographyTopography

Tower KarstTower Karst

SinkholesSinkholes

Closed depressions in the land surface formed Closed depressions in the land surface formed by dissolution of near-surface rocks or by the by dissolution of near-surface rocks or by the collapse of the roofs of underground channels collapse of the roofs of underground channels and caverns.and caverns.

Natural, common geologic feature in places Natural, common geologic feature in places underlain by soluble rocksunderlain by soluble rocks

Natural conditionsNatural conditions = they form slowly and = they form slowly and expand graduallyexpand gradually

UnnaturalUnnatural = dredging, constructing reservoirs, = dredging, constructing reservoirs, diverting surface water, and pumping ground diverting surface water, and pumping ground water can accelerate the rate of sinkhole water can accelerate the rate of sinkhole expansion - resulting in the abrupt formation of expansion - resulting in the abrupt formation of collapse-type sinkholes, some of which are collapse-type sinkholes, some of which are spectacular spectacular

Florida Florida SinkholesSinkholes

Most of central Florida underlain by limestone bedrockPopulation growth has drained ground waterSparse rainfall in the 70’s accelerated drawdown of water tableNumber of sinkholes increasedApprox 1/d in 80’s

Hydrothermal FeaturesHydrothermal Features Hot SpringsHot Springs GeysersGeysers FumarolesFumaroles

Hot SpringsHot Springs

Water heated Water heated below groundbelow ground

Sometimes due to Sometimes due to proximity of proximity of magmamagma

Finds path of Finds path of least resistance least resistance to surfaceto surface

Geysers FumarolesGeysers Fumaroles

Yellowstone National ParkYellowstone National Park

Geyser BasinsGeyser Basins Travertine TerracesTravertine Terraces

Yellowstone Yellowstone Geyser BasinsGeyser Basins

Chapter 18 Chapter 18

The Topography of Arid LandsThe Topography of Arid Lands

The TopographyThe Topographyof Arid Landsof Arid Lands

Running Water in Waterless Running Water in Waterless RegionsRegions

Ergs, Regs, and Hamadas Ergs, Regs, and Hamadas The Work of WindThe Work of Wind Desert Landform AssemblagesDesert Landform Assemblages

Arid LandsArid Lands

We are concerned with the processes We are concerned with the processes that shape arid lands – not just the that shape arid lands – not just the bordersborders

Usually think of desertUsually think of desert Not always soNot always so Can refer to semiarid, subhumid and Can refer to semiarid, subhumid and

humid regionshumid regions

Remember: Water is by far the most important external agent of landform development!

Terrain Forming ProcessesTerrain Forming Processes

Same processes in humid and arid Same processes in humid and arid areasareas

Desert landforms are much different Desert landforms are much different from those found in wetter areasfrom those found in wetter areas

Factors for difference:Factors for difference: WeatheringWeathering CreepCreep Soil & RegolithSoil & Regolith Impermeable surfacesImpermeable surfaces SandSand

RainfallRainfall DrainageDrainage WindWind Basins of Interior DrainageBasins of Interior Drainage VegetationVegetation

Considerable accumulation of sand forms sand dunes

Running Water in Arid RegionsRunning Water in Arid Regions Surface Water in the DesertSurface Water in the Desert

– Exotic StreamsExotic Streams– Ephemeral StreamsEphemeral Streams– PlayasPlayas

Fluvial ErosionFluvial Erosion– InselbergsInselbergs– PedimentsPediments

Fluvial DepositionFluvial Deposition

Exotic Stream: Exotic Stream: The Nile RiverThe Nile River

Flows for many hundreds of miles not being joined by tributaries

Pleistocene LakesPleistocene Lakes

Differential ErosionDifferential Erosion

BornhardtBornhardt

Piedmont ZonePiedmont Zone

Any deposition at the foot of a mountain range

Erg: A “Sea of Sand”Erg: A “Sea of Sand”

Classic “sea of sand”

Large area covered with loose sand

WindWind

Aeolian ErosionAeolian Erosion Aeolian TransportationAeolian Transportation Aeolian DepositionAeolian Deposition

– Desert DunesDesert Dunes– Coastal DunesCoastal Dunes– LoessLoess

Aeolian Aeolian ErosionErosion

Aeolian Aeolian TransportationTransportation

Horizontal transport

Fine grained sand

Larger bits moved by saltation and traction

Lack of vegetation to anchor

2 parts:

Deflation small, loose particles

Blowout depression

LoessLoessFine grained, calcerous and subject to vertically cohesive

Major Loess DepositsMajor Loess Deposits

Desert Landform AssemblagesDesert Landform Assemblages Basin-and-Range TerrainBasin-and-Range Terrain

– RangeRange– PiedmontPiedmont– BasinBasin

Mesa-and-Scarp TerrainMesa-and-Scarp Terrain– Differential ErosionDifferential Erosion

Landforms of the SouthwestLandforms of the Southwest

Basin-and-Range LandscapeBasin-and-Range LandscapePediment created from erosion not deposition

Piedmont created from deposition

Playas and Alluvial FansPlayas and Alluvial FansPlaya is a dry lake bed

Alluvial fan is part of a piedmont region - deposition

Mesa and Scarp Mesa and Scarp TerrainTerrain

Mesa and Scarp Mesa and Scarp FormationFormation

DesertificationDesertification

Chapter 20 Chapter 20

Coastal Processes and Coastal Processes and TerrainTerrain

Coastal Processes and TerrainCoastal Processes and Terrain

Coastal ProcessesCoastal Processes– Forces That Shape CoastlinesForces That Shape Coastlines– Coastal Sediment TransportCoastal Sediment Transport– Coastal DepositionCoastal Deposition

Coastal LandformsCoastal Landforms– Depositional LandformsDepositional Landforms– Shorelines of SubmergenceShorelines of Submergence– Coral CoastsCoral Coasts

What are coastlines?What are coastlines?

Coastlines are the transition from land Coastlines are the transition from land to waterto water

Not permanent featuresNot permanent features Always subject to erosion & depositionAlways subject to erosion & deposition They are at the interface of the 3 major They are at the interface of the 3 major

components of Earth’s environment:components of Earth’s environment:– HydrosphereHydrosphere– LithosphereLithosphere– AtmosphereAtmosphere

Coastal ProcessesCoastal Processes

WindWind is a major force – it moves the is a major force – it moves the water, creating waves and currentswater, creating waves and currents

Waves & currents shape coastlines Waves & currents shape coastlines and create topographic featuresand create topographic features

Waves = erosion = headlandsWaves = erosion = headlands Currents = deposition = beaches & Currents = deposition = beaches &

sandbarssandbars

Coastal ProcessesCoastal Processes

TidesTides Diastrophic EventsDiastrophic Events

– EarthquakesEarthquakes– VolcanoesVolcanoes

Sea or lake level changeSea or lake level change– Tectonic forcesTectonic forces– Eustatic changeEustatic change

Exceptions to Lakeshore ChangeExceptions to Lakeshore Change

Tidal range is insignificantTidal range is insignificant Water level rise/fall different processWater level rise/fall different process Coral reefs occur only in tropical or Coral reefs occur only in tropical or

sub-tropical sub-tropical oceansoceans.. Force of ocean water creates more Force of ocean water creates more

dramatic topographic featuresdramatic topographic features

WavesWaves

Waves are agents of erosion

Headlands are promontories of sloping land projected into the sea

WavesWaves

Appear to move but don’t, except Appear to move but don’t, except when they breakwhen they break

Energy passes through the water, Energy passes through the water, causing the water to undulatecausing the water to undulate

Most are wind generated – action of Most are wind generated – action of friction of wind moving across waterfriction of wind moving across water

Transfer of energy from wind to Transfer of energy from wind to water initiates wave actionwater initiates wave action

Small number of waves from volcanic Small number of waves from volcanic or diastrophic activityor diastrophic activity

Development of WavesDevelopment of Waves

Wave RefractionWave Refraction

Eustatic Sea Level ChangeEustatic Sea Level Change

Sea level change due to amount of Sea level change due to amount of water in sea/oceanwater in sea/ocean

Related to action Related to action of continental ice of continental ice sheetssheets

Ellesmere Island, Canada

TidesTidesCavendish Beach, PEI

Bay of Fundy, NS

Tidal CharacteristicsTidal Characteristics

Not significant agents of erosionNot significant agents of erosion Significant erosion only in narrow Significant erosion only in narrow

bays, margins of shallow seas, and bays, margins of shallow seas, and passages between islandspassages between islands

Normal High TidesNormal High Tides

What you should know about tides:

The Moon pulls at Earth – the Sun pulls at Earth and this is what causes tides

Position of Sun, Moon & Earth cause variation in tides

Highest Tidal RangesHighest Tidal Ranges

Stream OutflowStream Outflow

Madagascar

Stream outflow is a major contributor of sediment to oceans

This sediment is then transported by coastal waters

Erosion – Rocky CoastlineErosion – Rocky Coastline

Port Campbell, Australia

Most erosion along the coast is due to wave action

Air is forced into cracks in the rocks as the wave hits the shore

When the wave recedes, the air expands loosening the sections of rock

This is a major process of erosion

Erosion – Cliff CoastlineErosion – Cliff CoastlineWave Cut Notch

b) Erosion at sea level or just above

c) As notch is cut, cliff is undercut and falls away

d) The cliff face retreats, until it reaches bedrock - then you have a headland

Formation of ArchesFormation of Arches

Victoria, Australia

1985

1992

Continuous pounding wave action

Erosion - SandErosion - Sand

Currents and tides cause erosionCurrents and tides cause erosion Storms accelerate erosionStorms accelerate erosion A major storm can remove an entire A major storm can remove an entire

beach in a few hours – eroding down beach in a few hours – eroding down to the bedrockto the bedrock

Sediment TransportSediment Transport Nearly all sediment transport on Nearly all sediment transport on

coastlines is accomplished by wave coastlines is accomplished by wave action and action and locallocal currents currents

Mechanisms:Mechanisms: Longshore CurrentsLongshore Currents strike at an strike at an

angle almost parallel to the shore - angle almost parallel to the shore - “along the shore”“along the shore”

Beach DriftingBeach Drifting is downwind is downwind displacement of particles along coastdisplacement of particles along coast

Movement with ebb and surge of tide Movement with ebb and surge of tide tumbles particles and reduces sizetumbles particles and reduces size

Coastal Coastal Sediment Sediment TransportTransport

Longshore Current

DepositionDeposition

Most coastal deposition is of fine Most coastal deposition is of fine sand particlessand particles

During storms larger particles/pieces During storms larger particles/pieces can be moved and depositedcan be moved and deposited

Sediment BudgetSediment Budget is the balance of is the balance of eroded and deposited materialeroded and deposited material

Coastal LandformsCoastal Landforms

Depositional LandformsDepositional Landforms– BeachesBeaches– Barrier Islands/LagoonsBarrier Islands/Lagoons– SpitsSpits

Shorelines of SubmergenceShorelines of Submergence– Fjorded CoastsFjorded Coasts– Wave-Cut Cliffs and PlatformsWave-Cut Cliffs and Platforms– Marine TerracesMarine Terraces

Coral CoastsCoral Coasts

BeachesBeachesAn exposed deposit of loose sediment adjacent to a body of water

Backshore: landward of HWL

Foreshore: zone of tidal rise & fall

Offshore: zone always underwater

Barrier Barrier IslandsIslands

Long narrow sandbars built up in shallow offshore water

Usually parallel to shore

Barrier Islands Barrier Islands and Lagoonsand Lagoons

Water is isolated between barrier islands and main land

Eventually merge with barrier and mainland if sediment deposit not interrupted

SpitsSpitsLinear deposit attached to land at one end and extending into open water in down current direction

Coral CoastsCoral Coasts

Great Barrier Reef, Australia

In tropical oceans, most continents and islands are fringed with coral reefs

The coral is composed of polyps – tiny marine animals

They secrete external skeletons of calcium carbonate

Fringing Fringing ReefsReefs

Attached to the coast of volcano

Barrier Reefs and AtollsBarrier Reefs and Atolls

Atoll is a ring shaped coral structure surroundig a landless lagoon

Usually just at sea level

Barrier reef is aging fringe reef

Volcano is sinking and lagoon forms between reef and volcano

Coral Reefs of the WorldCoral Reefs of the World