OceanographyOceanography&&

BeachesBeaches

Unit 8Unit 8

Follow the directions at the bottom

of the page.

COLOR it LAST!!!

Use your textbook to

find the features it asks for.

Helpful Book Pages:Helpful Book Pages:Page 31Page 31Page 449Page 449

Pages 396-397Pages 396-397

The Ocean Floor - The Vast World Ocean

Origin of the OceansOrigin of the Oceans

How old is the Earth? 4.6 billion years old

Where did the water come from?

1. Comets and Meteorites: - Carry lots of water, which transferred to Earth upon impact

2. Volcanism:

-volcanic gas has mostly water vapor and CO2

-The CO2 and other gases formed the Earth's atmosphere

-As the Earth cooled, the water vapor condensed, forming the oceans.

The Blue PlanetThe Blue Planet

Earth is known as the "Blue Planet" because ~71% of it is covered by oceans.

-Average Depth of the Oceans: 3800 m (3.8 km)-Where is most of the water - Northern or Southern Hemisphere?

Southern-All oceans are really one big body of water.-97% of the water on Earth is found in the oceans.

Only 3% is freshwater.

-OCEANOGRAPHY = study of Earth's oceans

Sea Level = level of the ocean's surfaces.

-Sea Level has risen and fallen by hundreds of meters due to the...

-Ice Caps melting (H2O level rises) and Glaciers expanding

(H2O level falls)

-Sea Level is also affected by tectonics.

-TECTONICS = movement of Earth's landmasses.

-Tectonics can change the level of the seafloor, thus

changing sea levels.

-Currently, sea level is rising 1-2mm/year due to melting glaciers

GEOGRAPHY of the OCEANS

There are 4 major Oceans:

-Pacific, Atlantic, Indian, & Arctic

Largest = Pacific

Smallest = Arctic

Sea Ice: Ice is ( more / less ) dense than water, so it floats.

SEAS = smaller than oceans, and partially or fully landlocked.

-All seas and oceans belong to one global ocean, whose waters

are thoroughly mixed.

Mapping the Ocean FloorMapping the Ocean Floor

The topography of the ocean floor is as diverse as that of the continents.

Bathymetry = measurement of the ocean floor (bathos = depth, metry = measurement)

Began with the ship "Challenger" in the 1870s-Although today's technology is much more sophisticated!!

SONAR was first used in the 1920s to map the seafloor features of the S. Atlantic Ocean.

SONAR = SOund NAvigation and RangingHow does it work? Uses echoes of sound, return time, and velocity of sound in water to measure depth.

-See p. 398 in text.Drain the Ocean- Nat Geo

Side-Scan Sonar = aim SONAR at angles.

It is used to map underwater hills, trenches, ridges, etc.

SATELLITES continually gather information about the ocean floor.

-Data has shown that the ocean surface is not totally flat...

-Why??

- Gravity attracts water toward regions where

massive ocean floor features occur.

- Mountains/Ridges have elevated water.

Trenches have depressions.

SUBMERSIBLES (small underwater crafts) give us much data.

Manned crafts:

-Trieste - Jacques Piccard (1960)

-Went to the Mariana Trench (10,912m)

-Alvin - 4000m

-Sea Cliff II - 6000m

Unmanned crafts:

called AUVs

(autonomous underwater vehicles)

Deep Sea Exploring

Use pages 401-406 in your textbook, Use pages 401-406 in your textbook, defining each term and labeling the diagrams.defining each term and labeling the diagrams.

Seafloor SpreadingSeafloor Spreading

HydrothermalHydrothermal VentVent

Define but Define but do not label:do not label:

ContinentContinental

MarginContinental

ShelfContinental

SlopeContinental Rise

Submarine Canyon

Abyssal PlainSeamount

TrenchMid-Ocean

RidgeRift Valley

Volcanic IslandFringing ReefBarrier Reef

Atoll

“See” the Ocean Floor

Work on WorksheetWork on Worksheet

Types of Coral ReefsTypes of Coral ReefsFringing- directly attached to the shore of a volcanic island. No lagoon present.

Atoll- Circular coral reef that surrounds a central lagoon of quiet water. Forms on top of the cone of a submerged volcano island.

Barrier- A lagoon of open water separates reef from the nearby land. Largest is Great Barrier Reef, Australia (1,200 mi long and 62 mi wide)

FRINGING REEFFRINGING REEF

ATOLL REEFATOLL REEF

BARRIER REEFBARRIER REEF

14.1 - 14.2 Quiz:

1. Largest Ocean2. Ocean that is on the EAST side of Africa3. Name one place where our ocean's water came from. (there were 3)4. What does SONAR stand for?5. Name the 3 parts of the Continental Margin, IN

ORDER, going from the beach into the ocean.6. What is the name for the deep, very flat part of the

ocean floor?7. Which comes first: Atoll, Fringing Reef, or Barrier Reef?8. What is the name for a dormant seamount that has

been eroded?9. What is the name for the deep cut in the ocean floor

that is only found in the abyssal plain?

Word bank (some answers are here, but not all of

them!)

Continent Abyssal plain

Seamount Volcanic island

Submarine canyon Continental shelf

Continental marginGuyotTrench

Mid-ocean ridgeContinental rise

Rift valleyContinental slope

1. Pacific2. Indian3. Any of these: meteorite, comets, volcanoes4. Sound Navigation and Ranging5. 3 points: IN ORDER:

Cont.Shelf, Cont.Slope, Cont.Rise6. Abyssal Plain7. Fringing Reef8. Guyot9. Trench

ANSWERS!!!

Continental shelf

Contin

enta

l

Slo

pe

Continental Rise

Abyssal Plain

Inter-Tidal Zone Area of

shoreline between high and low tides

Photosynthetic Zone: light penetrates for photosynthesis. Up to 150 m (488ft)

Benthic Environment:

Ocean bottom or floor

Abyssal Zone: 4000-6000m

Continental Margin (shelf, slope, rise)

~200m

4000 m

Hadal Zone

High Tide

Low Tide

>6000m

MAJOR OCEANIC ZONES

Bathyal Zone: Darkness

THERMOCLINE ~200-100ft

Brainpop-Ocean Floor

Work on the Review & Reinforcement WKST

“Physical Properties of the Ocean Life Zones”

Ocean Water and Ocean LifeTHE COMPOSITION OF SEAWATER

SALINITY

Salinity: the total amount of solid material dissolved in water.

Seawater is about 96.5 % water and 3.5 % dissolved salts.

Expressed as grams of salt per kilograms of water (or parts per thousand - ppt)

Average salinity: 35 ppt (3.5 %)

Most abundant salt in seawater: sodium chloride (NaCl)

Seawater also has dissolved gases and nutrients

Sources of Sea Salts: chemical weathering of rocks and volcanism

Processes Affecting Salinity:

– Adding water decreases salinity: precipitation, runoff, icebergs &

sea ice melting

– Losing water increases salinity: evaporation, formation of sea ice

o How does salinity increase when sea ice forms?

When ice forms, salt is left behind in the water.

OCEAN TEMPERATURE VARIATIONOCEAN TEMPERATURE VARIATION

·Surface Layer Temperatures: Varies with the amount of solar radiation received, which is a function of latitude.

Middle latitudes (near the equator) have higher temperatures, and vice versa.

Temperature Variation with Depth:– Colder water is denser than warmer water, so cold water will

sink. – Deeper = Colder!–Three temperature layers:

– Surface layer: warmest– Thermocline: (300m-1000m) a rapid change of temperature

with depth. – It creates a vertical barrier to many types of marine life.– Bottom layer: coldest

– In polar regions, the surface layer & thermocline don't exist because it's too cold.

OCEAN DENSITY VARIATION

– Density varies with depth due to both temperature and salinity.

– Denser Water = ( colder or warmer ) and ( salty or fresh ) ... why floating

is easier in the ocean!

Density Lab

Warmup Quiz:

1) Does adding or losing water increase salinity?

2) Name one way the Earth naturally decreases salinity.

3) What does PPT stand for?

4) Name the ocean region: the temperature rapidly changes as you go deeper.

5) In the ocean, the deeper the water, the colder / warmer and saltier / fresher it is.

Ocean Waves The Dynamic OceanOCEAN CIRCULATION & WAVES AND TIDES

4 Movements of the Ocean: Waves, Tides, Currents & Upwellings

WAVES =

Rhythmic movement that carries energy through space or matter (water)

- Generated mainly by wind

- As a wave passes, water moves in a circle, returning to its

original position.

-The water doesn't move forward, only the energy.

··Wave Measurements:

- Highest point = crest. Lowest point = trough.

- Distance from Crest to Trough = wave height.

- Distance from Crest to Crest (or trough to trough)

wavelength.

- Wave speed increases with wavelength.

- - As waves reach the shallow water near a shoreline, energy is lost due to friction against the seafloor. This slows the wave.

- Incoming wave crests catch up with slower crests, decreasing the wavelength.

- Waves get higher, steeper, and unstable, causing the crests to collapse.

- Collapsing wave crests = breakers.

Science of Surf

TIDES = periodic rise and fall of sea level

· High Tide = highest level

· Low Tide = lowest level

· Tidal Cycles (High Tide Low Tide High Tide) usually =

24 hrs 50 mins

-Diurnal: 1 high tide, 1 low tide every day

-Semidiurnal: 2 high tides, 2 low tides every day

(this is what we have in NC)

-Mixed: 1 high, 1 low, 1 semi-high, 1 semi-low every day

Causes of Tides:

-Gravitational Pull of the Moon and the Sun

-Spring Tide = High tide is highest, low tide is

lowest.

-Neap Tide = High tide is lower than usual,

low tide higher than usual.

Which is bigger - Solar or Lunar tides? Why??

-Moon is closer, so it has more gravitational pull

Brainpop TidesDiscovery Ed- Tides

Warm-up QuizWarm-up Quiz

1) What are the two things that cause tides?

2) In an ocean wave, the ______ moves forward, and the _____ moves in a circle.

3) What is a collapsing wave called?

4) What happens to the wave speed when the wavelength increases?

5) What kind of tidal cycle has 2 high tides and 2 low tides every day?

OCEAN CURRENTSCURRENT = movement of a section of water

- Density Current = controlled by density. Move very slowly.- Surface Current = controlled by wind. Move very quickly.

-Only affect the top few hundred meters of water

- Continents deflect some currents so that they join other currents,causing a circular current, called a gyre.

- 5 Major Gyres: North & South Pacific, North & South Atlantic, and Indian Ocean

- In the Northern Hemisphere, the gyres circulate in a clockwise direction.

-In the Southern Hemisphere, the gyres circulate counterclockwise.

Brainpop Ocean CurrentsOcean Currents- Discovery Ed

Currents flow westward near the equator. When they hit land, they are deflected toward the poles. This carries

warm water to colder regions of the world.

When it gets to the polar regions, the water cools and is deflected back toward the equator on the other side of

the ocean.

UPWELLINGUPWELLING

·· Water not only moves horizontally (currents) but it Water not only moves horizontally (currents) but it also moves vertically.also moves vertically.

·· UPWELLING = upward motion of ocean waterUPWELLING = upward motion of ocean water

·· Cold water flows upward to replace Cold water flows upward to replace warm surface water blown out to warm surface water blown out to sea by offshore winds. sea by offshore winds.

·· They mainly occur on western coasts.They mainly occur on western coasts.

·· Rich in nutrients, thus supporting lots of marine life.Rich in nutrients, thus supporting lots of marine life.

Wave movement toward the shore often builds up a strip Wave movement toward the shore often builds up a strip of sediment at the coastline called a of sediment at the coastline called a beachbeach..

Beaches are composed of whatever sediment is Beaches are composed of whatever sediment is

available, but most beaches are composed of available, but most beaches are composed of sandsand..

BEACHES

Wave ImpactBreaking waves against land causes cracks and crevaces to open in cliffs. Water is forced into these displacing air. Air

expands and disloge rock fragments & extends features.

AbrasionSawing and grinding action of rock fragments in water.

Wave Refraction• Bending of waves affecting distribution of energy along the shore. • Influences erosion, sediment transfer & deposition take place• Concentrated at headlands

Longshore Transport• Current that flows parallel to the shore and moves large

amounts of sediment.• Caused by bending of waves.

EROSIONALFEATURES

Created by L. Zimmerman

• During storms waves can be much more powerful than normal.During storms waves can be much more powerful than normal.

Created by L. Zimmerman

During these times During these times the beach tends to the beach tends to erode moreerode more and the and the sand is carried back sand is carried back into the ocean.into the ocean.There it is usually There it is usually depositeddeposited as as underwater bars underwater bars parallel to the shore.parallel to the shore.

Wave-Cut CliffsCutting action of the surf against the base of coastal land

PlatformsFlat, bench like surface is left from cutting waves.

Sea ArchesSurf wears away softer rock & cave forms.

When two caves connect, a sea arch is formed.

Sea StackSea arch falls into the ocean leaving isolated piece.

DEPOSITIONAL FEATURES

SpitElongated ridge of sand that projects from land into the

mouth of an adjacent bay

BarForm across a bay where currents are weak.

TomboloRidge of sand that connects an island to the

mainland or to another island

Created by L. Zimmerman

If these sand bars rise above the average sea level If these sand bars rise above the average sea level winds will help to pile up sediment.winds will help to pile up sediment.

When vegetation begins to grow and stabilize the When vegetation begins to grow and stabilize the offshore sediment pile, a offshore sediment pile, a barrier islandbarrier island is created. is created.

Created by L. Zimmerman

Hatteras – Ocracoke Island, NC

Pamlico Sound (Land Side)

Atlantic Ocean – Sea Side

Barrier Island

Barrier IslandNarrow sandbars parallel to but separated from the coast by

3-30 km offshore (300 on US coast in NC, MA, TX, SC)

STABILIZINGTHE SHORE

GroinBarrier built at a right angle to shore to keep sand in place

BreakwallBarrier built perpendicular to the shore to stop incoming

waves from damaging shore.

SeawallBarrier built parallel to the shore to stop incoming waves

from damaging shore.

Seawalls

Pros & Cons to groins, breakwaters & seawalls

• PRO–Protect shoreline & boats from wave action impact &

erosion

• Con–Temporary structure–Interfere with natural process of erosion & deposition–More structures must be built

The Barrier Islands on the Outer Banks