the coast. chapter 11 homework coast shore beach moraine delta alluvial plain sea stack berm tombolo...

The CoastThe Coast

Chapter 11 Homework• Coast• Shore• Beach• Moraine• Delta• Alluvial Plain

• Sea stack• Berm• Tombolo• Accretion• Jetty• Groin

Questions pg 307 2,4,7,9,12,14

Major Zone• Coastal zone: The area that is Coastal zone: The area that is

changed by the processes of the sea changed by the processes of the sea from the breaker zone to the uplands from the breaker zone to the uplands of the shore.of the shore.

• Shore: Outer limits of the waves down Shore: Outer limits of the waves down to the area that the waves directly to the area that the waves directly influenceinfluence

Types of Coast• Primary CoastsPrimary Coasts

-Glaciers-Glaciers

-Sea level rise-Sea level rise

-River runoff erosion-River runoff erosion

-Tectonic plate moving-Tectonic plate moving

Types of Coast Cont.• Secondary Coast: formed by marine Secondary Coast: formed by marine

processes.processes.

-Wave Action-Wave Action

-Storms-Storms

-Currents-Currents

Barrier Beaches• Characteristics of Barrier BeachesCharacteristics of Barrier Beaches

A. Elongated narrow landformsA. Elongated narrow landforms

B. Composed of sand and other B. Composed of sand and other loose loose sediments transported by sediments transported by waves, waves,

currents, storm surges, and wind.currents, storm surges, and wind.

C. Dynamic (Eroding or accreting)C. Dynamic (Eroding or accreting)

D. Low land massesD. Low land masses

Barrier Beaches Cont.• Functions of Barrier BeachesFunctions of Barrier Beaches

A. Protect mainland, sounds, salt A. Protect mainland, sounds, salt marshes, sand, and mud flats from marshes, sand, and mud flats from ocean energies (wave attack)ocean energies (wave attack)

B. Locations for lighthouses, fishing B. Locations for lighthouses, fishing

communities, Coast Guard stations and communities, Coast Guard stations and ports.ports.

C. Aesthetic ValueC. Aesthetic Value

D. Valuable habitat for mammals, D. Valuable habitat for mammals, waterfowl, fish, and shellfishwaterfowl, fish, and shellfish

Barrier Beaches Cont.Barrier Beaches Cont.E. Development/Tourism E. Development/Tourism

Leads to Leads to research to determine research to determine their geologictheir geologic and ecologic and ecologic characteristics to definecharacteristics to define

barrier carrying capacities and barrier carrying capacities and susceptibility to storm damagesusceptibility to storm damage

Barrier Beaches Cont.• Location of BarriersLocation of Barriers

A. Found from the rocky A. Found from the rocky headlands headlands of Maine to the salt flats of Maine to the salt flats of south Texasof south Texas

B. Protect 2700 miles of shorelineB. Protect 2700 miles of shoreline

Barrier Island Types• Barrier Spit- barrier beaches that are Barrier Spit- barrier beaches that are

attached at one end to a source of attached at one end to a source of sediment and extend into open water.sediment and extend into open water.– Caused by long shore currents moving Caused by long shore currents moving

abundant sand and gravel from eroding abundant sand and gravel from eroding cliffs.cliffs.

– Types of SpitsTypes of Spits• SimpleSimple• DoubleDouble• RecurvedRecurved• ComplexComplex

Barrier Island Types Cont.– Location of barrier spitLocation of barrier spit– MaineMaine

• New JerseyNew Jersey• MassachusettsMassachusetts• VirginiaVirginia

Barrier Island Types Cont.• Barrier Island- barrier beaches not Barrier Island- barrier beaches not

connected to source of sediment (most connected to source of sediment (most commonly recognized offshore commonly recognized offshore structure)structure)

• Classified according toClassified according to– Tide- Microtidal- less than 6 feet and Tide- Microtidal- less than 6 feet and

Mesotidal- 6-12 feetMesotidal- 6-12 feet– Sand supply- Transgressive- sand deficiency Sand supply- Transgressive- sand deficiency

and Regressive- accretion- multiple dune and Regressive- accretion- multiple dune ridges)ridges)

Barrier Island Types Cont.• Types of Barrier IslandsTypes of Barrier Islands

– Microtidal Transgressive- Outer BanksMicrotidal Transgressive- Outer Banks– Microtidal Regressive- Bogue and Microtidal Regressive- Bogue and

Shackleford BanksShackleford Banks– Mesotidal Transgressive- Morris and Mesotidal Transgressive- Morris and

Caper Islands in SCCaper Islands in SC– Mesotidal Regressive- Bulls Island in SCMesotidal Regressive- Bulls Island in SC– Capes- Barrier islands that project in to Capes- Barrier islands that project in to

the sea to form a right-angled shoreline. the sea to form a right-angled shoreline. Hatteras, Lookout, FearHatteras, Lookout, Fear

Barrier Island Types Cont.• Bay Barriers- barrier beaches that are Bay Barriers- barrier beaches that are

connected at both ends to headlands- connected at both ends to headlands- Northern New EnglandNorthern New England– Types of bay barriersTypes of bay barriers

• Baymouth Barriers- connect head lands Baymouth Barriers- connect head lands together- Martha’s Vineyard, Mass. and RI together- Martha’s Vineyard, Mass. and RI shorelineshoreline

• Tombolo- Island attached to headland Tombolo- Island attached to headland (glacial or volcanic in origin) EX California (glacial or volcanic in origin) EX California CoastCoast

Origin of Barrier Beaches• Ridge submergenceRidge submergence

– As sea level rose, dune ridges on As sea level rose, dune ridges on seaward edge of mainland became seaward edge of mainland became barrier islands.barrier islands.

– Lower areas behind these ridges were Lower areas behind these ridges were flooded, creating lagoons (sounds).flooded, creating lagoons (sounds).

– Major means of barrier formation along Major means of barrier formation along the Southeast Atlantic USAthe Southeast Atlantic USA

Origin of Barrier Beaches Cont.

• Submarine bar upbuildingSubmarine bar upbuilding– Material from the nearshore bottom is Material from the nearshore bottom is

transported landward by waves to form transported landward by waves to form an offshore baran offshore bar

– Eventually builds above sea level as Eventually builds above sea level as barrier beachbarrier beach

– Some small Gulf Coast barrier islands Some small Gulf Coast barrier islands have originated this way.have originated this way.


• Spit AccretionSpit Accretion– Sand is transported by littoral drift Sand is transported by littoral drift

(longshore currents) and builds up to (longshore currents) and builds up to form a spitform a spit

– If inlets form the spit may become an If inlets form the spit may become an islandisland

– Example- Barrier island system of Cape Example- Barrier island system of Cape Cod and south shore of Long IslandCod and south shore of Long Island


• Delta sediment changesDelta sediment changes– Small barriers form on deltas through Small barriers form on deltas through

wave action and reworking of river wave action and reworking of river sedimentssediments

– Example- Mississippi Delta and along the Example- Mississippi Delta and along the coast of Mainecoast of Maine

Barrier Evolution- “The Sand Sharing System" Cont.

• Causes of evolution of barriersCauses of evolution of barriers– Rate of sea level rise- If sea level rises 1 Rate of sea level rise- If sea level rises 1

ft, the barrier must move 100-1,000 ft or ft, the barrier must move 100-1,000 ft or it will drownit will drown

– Sand supply- from offshore and from Sand supply- from offshore and from other barriersother barriers

– Sea Energy-stormsSea Energy-storms– Littoral drift- average 500,000 cubic yards Littoral drift- average 500,000 cubic yards

per year. 1,000,000 cubic yards at Cape per year. 1,000,000 cubic yards at Cape HatterasHatteras


– Inlet DynamicsInlet Dynamics– OverwashOverwash– Dune migrationDune migration– Human InterventionHuman Intervention


• Examples of barrier evolutionExamples of barrier evolution– Storm erosion and natural beach repairStorm erosion and natural beach repair

• During storms sand is carried offshore to During storms sand is carried offshore to submerged ridges (storm bars)submerged ridges (storm bars)

• Gentle waves cause these bars and runnels Gentle waves cause these bars and runnels (troughs) to migrate landward and rejoin (troughs) to migrate landward and rejoin beachbeach

• A change in any factor may result in a A change in any factor may result in a changed beachchanged beach


• Landward migrationLandward migration– This is often called erosion, but the term This is often called erosion, but the term

retreat is more accurate.retreat is more accurate.– Barriers have been migrating landward Barriers have been migrating landward

since their creation. Have moved 20-70 since their creation. Have moved 20-70 miles landwardmiles landward

– Transported sand buries backbarrier Transported sand buries backbarrier environments. New marshes develop environments. New marshes develop farther landward on leading edge of new farther landward on leading edge of new sediment.sediment.


– Evidence 1) Core samples of beaches Evidence 1) Core samples of beaches show marsh peat under dunes. 2) Salt show marsh peat under dunes. 2) Salt marsh peat, oyster and tree stumps marsh peat, oyster and tree stumps exposed on beach after stormexposed on beach after storm

– Migration speed varies 1) Nauset Island, Migration speed varies 1) Nauset Island, Mass. Has rapid migration. 2) Hatteras Mass. Has rapid migration. 2) Hatteras Is. Has remained static and is eroding on Is. Has remained static and is eroding on ocean and sound sideocean and sound side


• Causes of sand transportation to back Causes of sand transportation to back barrier environmentsbarrier environments– Storms- Major amount of sand transport Storms- Major amount of sand transport

occurs during 1) Northeasters occurs during 1) Northeasters

2) Hurricanes2) Hurricanes– Inlet dynamicsInlet dynamics

• During a storm, waves wash over at low places During a storm, waves wash over at low places in dunein dune

• High water blown by winds create inletHigh water blown by winds create inlet• Creation of flood tidal delta in bayCreation of flood tidal delta in bay


• Delta growsDelta grows• Longshore currents cause inlets to migrate Longshore currents cause inlets to migrate

southward- delta grows moresouthward- delta grows more• Water path becomes long and tortuousWater path becomes long and tortuous• Inlet closes and marsh grows on old flood Inlet closes and marsh grows on old flood

tidal deltatidal delta• Barrier beach is widenedBarrier beach is widened


– Overwash ProcessesOverwash Processes• Storm surges allow waves to wash over beach Storm surges allow waves to wash over beach

and push sand from beach and dune zone.and push sand from beach and dune zone.• Often viewed as a disaster, however it is a Often viewed as a disaster, however it is a

continuous process. It enables barrier island to continuous process. It enables barrier island to migrate landward (roll overmigrate landward (roll over

• Overwash fans eventually bury marsh, new Overwash fans eventually bury marsh, new marsh developsmarsh develops

• Barrier beach is displaced land ward, but Barrier beach is displaced land ward, but ecological units retained.ecological units retained.

• Overwash process depends on barrier Overwash process depends on barrier exposure, orientation, storm frequency, tidal exposure, orientation, storm frequency, tidal range, and vegetation species.range, and vegetation species.


– Dune migrationDune migration• Principle means of landward migration along Principle means of landward migration along

some barriers (Mass.) can be accelerated by some barriers (Mass.) can be accelerated by human interventionhuman intervention..

• Aeolian transport (wind) results in dune Aeolian transport (wind) results in dune formation using sand from beach or formation using sand from beach or overwash fan into areas with fences or overwash fan into areas with fences or vegetation to anchor sand.vegetation to anchor sand.

• Dunes can migrate and bury salt marshes Dunes can migrate and bury salt marshes and maritime forests. (Jockey’s Ridge)and maritime forests. (Jockey’s Ridge)

the coast. chapter 11 homework coast shore beach moraine delta alluvial plain sea stack berm tombolo...

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