Oceanography PPT

1. OceanographyOceanography&&
BeachesBeaches
Why the Ocean Matters?Why the Ocean Matters?

2. 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 31
Page 449Page 449
Pages 396-397Pages 396-397

3. 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.

4. he Blue Planethe Blue Planet
arth is known as the "Blue Planet" because ~75% of it is covered
y 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

5. 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

7. 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.

8. 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 Ranging
How 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

9. Side-Scan Sonar = aim SONAR at angles.
t 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.

10. 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

11. 14.1 - 14.2 Quiz:
1. Largest Ocean
2. Ocean that is on the EAST side of Africa
3. 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?

12. 1. Pacific
2. Indian
3. Any of these: meteorite, comets, volcanoes
4. Sound Navigation and Ranging
5. 3 points: IN ORDER:
Cont.Shelf, Cont.Slope, Cont.Rise
6. Abyssal Plain
7. Fringing Reef
8. Guyot
9. Trench
ANSWERS!!!

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

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

15. 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)

18. Ocean Water and Ocean Life
THE 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.
•• Average salinity: 35 ppt (3.5 %)
• Most abundant salt in seawater: sodium chloride (NaCl)
•Seawater also has dissolved gases (CO2) and nutrients
•Sources of Sea Salts: chemical weathering of rocks and volcanism

19. 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.

20. 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.

21. 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.

22. 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

23. Warmup Quiz:
1) Does adding or losing water increase salinity?
2) Name one way the Earth naturally decreases salinity.
3) How does density affect ocean currents?
4) In the ocean, the deeper the water, the colder / warmer
and saltier / fresher it is.
5) What are the two (2) factors that influence the
density of ocean water?

24. Density Lab Questions
1. What is density?
2. Which has a higher density, salty water or fresh water?
3. Which has a higher density, cold water or warm water?
4. How would an increase in evaporation effect the density of ocean water?
5. Which would contain more water molecules? Explain.
6. When seawater freezes in polar regions, most of the salt is left behind. How would this effect the
density of the water that is left unfrozen?

25. The Dynamic Ocean
OCEAN 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.

26. ve Measurements:
ighest point = crestcrest. Lowest point = troughtrough.
istance from Crest to Trough = wave heightwave height.
istance from Crest to Crest (or trough to trough)
wavelength.
Wave speed decreases with wavelength.

27. -- As waves reach the shallow water near a shoreline, energyenergy
is lost due to frictionis 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 = breakersbreakers.
Science of Surf

28. OCEAN CURRENTS
CURRENTCURRENT = movement of a section of water
- Density CurrentDensity Current = controlled by density. Move very slowly.
- Surface CurrentSurface Current = controlled by wind. Move very quickly.
-Only affect the top few hundred meters of water

29. Currents flow westwardwestward near the equator. When they
hit land, they are deflected toward the poles. This
carries warm water to colder regionswarm 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.
This creates large GYRES!

30. GYRES
 - 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. DUE to the CORIOLIS Effect
 -In the Southern Hemisphere, the gyres circulate

31. The North Pacific Gyre

33. UPWELLINGUPWELLING
·· Water not only moves horizontally (currents) but itWater not only moves horizontally (currents) but it
also moves vertically.also moves vertically.
·· UPWELLING =UPWELLING = upward motion of ocean waterupward motion of ocean water
·· Cold water flows upward to replaceCold water flows upward to replace
warm surface water blown out towarm 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.

34. 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

35. Spring and Neap 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
Discovery Ed-
Tides

36. Created by L. Zimmerman
Ocean Waves
The most important agent
shaping coastal landforms
is wave action.
And WHY do you need to
know this? – because
North Carolina has a
unique coastal barrier
island and 100’s of miles of
shoreline!

37. Created by L. Zimmerman
Ocean Waves1.1. Most of the ocean’s surface waves are caused byMost of the ocean’s surface waves are caused by
thethe WINDWIND..
 As wind moves over the ocean, it produces waves and currents
that erode the bordering land.
 Waves can also be produced by underwater earthquakes and the
effect of the moon in producing tides.

38. Created by L. Zimmerman
Normal winds rarely
produce ocean waves
higher than 15m.
2. The wind determines the size of the
wave and depends on:
 Time
 Strength of the wind
 Fetch
3.3. FetchFetch is the length of open water over
which the wind blows..

39. Created by L. Zimmerman
4. The distance from crest to crest is the WAVELENGTHWAVELENGTH
• Each particle moves in place in a circular motion.
• This motion occurs below the surface as well, in
smaller and smaller circles.

40. Created by L. Zimmerman
SURF
5. When waves enter
shallow water near
the shore, they dragdrag
against the bottom.
 The waves then
become unstable and
water rushes toward
the shore as breakingbreaking
waveswaves oror surfsurf.

41. Created by L. Zimmerman
6.6. Wave movement toward the shore often builds up aWave movement toward the shore often builds up a
strip of sediment at the coastline called astrip of sediment at the coastline called a beachbeach..
77. Beaches are composed of whatever sediment is. Beaches are composed of whatever sediment is
available, but most beaches are composed ofavailable, but most beaches are composed of sandsand..

42. Created by L. Zimmerman
8. Waves moving at an angle to the
shoreline push water along the
shore creating a longshore currentlongshore current.
 A longshore current is a
movement of water parallel to
and near the shoreline.
 Longshore currents transport
sand in a direction parallel to the
shoreline.

43. Created by L. Zimmerman
 Sand moving along a
relatively straight shore
keeps moving until the
shoreline changes
direction.
 This happens at bays and
headlands.
 Here the longshore current
slows and sand is
deposited at the near end
of the headland.
9. A long narrow deposit of
sand connected at one end
to the shore is called a
spitspit.

44. Created by L. Zimmerman
SPIT

45. Created by L. Zimmerman
Long Point, Lake Erie, Canada
Long Shore Current
Long Shore Current

46. Created by L. Zimmerman
Rip Currents
Signs that a rip current is
present are very subtle and
difficult for the average
beachgoer to identify.
Look for differences in the
water color, water motion,
or incoming wave shape.

47. Created by L. Zimmerman
Oregon Inlet – Nags Head, NC

48. Created by L. Zimmerman
 During storms waves can be much moreDuring storms waves can be much more
powerful than normal.powerful than normal.

49. Created by L. Zimmerman
10. During these10. During these
times the beachtimes the beach
tends totends to erodeerode
moremore and the sandand the sand
is carried back intois carried back into
the ocean.the ocean.
There it is usuallyThere it is usually
depositeddeposited asas
underwater barsunderwater bars
parallel to theparallel to the
shore.shore.

50. Created by L. Zimmerman
11. If these sand bars rise above the average sea11. If these sand bars rise above the average sea
level winds will help to pile up sediment.level winds will help to pile up sediment.
When vegetation begins to grow and stabilize theWhen vegetation begins to grow and stabilize the
offshore sediment pile, aoffshore sediment pile, a barrier islandbarrier island is created.is created.

51. The Barrier Islands on the
Outer Banks

52. Created by L. Zimmerman
Hatteras – Ocracoke Island, NC
Pamlico Sound (Land Side)
Atlantic Ocean – Sea Side
Barrier Island

53. EROSIONAL
FEATURES

54. Wave Impact
Breaking 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.

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

56. Wave-Cut Cliffs
Cutting action of the surf against the base of coastal land

57. Platforms
Flat, bench like surface is left from cutting waves.

58. Sea Arches
Surf wears away softer rock & cave forms.
When two caves connect, a sea arch is formed.

59. Sea Stack
Sea arch falls into the ocean leaving isolated piece.

60. DEPOSITIONAL
FEATURES

61. Barrier Island
Narrow sandbars parallel to but separated from the coast
by 3-30 km offshore (300 on US coast in NC, MA, TX, SC)

62. Spit
Elongated ridge of sand that projects from land into theElongated ridge of sand that projects from land into the
mouth of an adjacent baymouth of an adjacent bay

63. Bar
Form across a bay where currents are weak.Form across a bay where currents are weak.

64. Tombolo
Ridge of sand that connects an island to theRidge of sand that connects an island to the
mainland or to another islandmainland or to another island

65. STABILIZING
THE SHORE
Man-made structuresMan-made structures
designed to “SAVE” thedesigned to “SAVE” the
beaches and/or protectbeaches and/or protect
coastal erosioncoastal erosion

66. Created by L. Zimmerman
Man-Made structures – Help or Hindrance?
12. Jetties and groinsJetties and groins are structures designed to modify or
control sand movement..
 Groins extend like fingers away from the shore.
 Jetties are built where a river empties into ocean.

67. Created by L. Zimmerman
The Problem????

68. Groins and Jetties
Barrier built at a right angle to shore to keep sand in place

69. Breakwall
Barrier built perpendicular to the shore to stop
incoming waves from damaging shore.

70. Seawall
Barrier built parallel to the shore to stop incoming
waves from damaging shore.

71. 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