Powerpoint notes for High school oceanography unit in Earth Science. Course being taught in North Carolina

1. Oceanography
Beaches
&
Unit 8

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:
Page 31
Page 449
Pages 396-397

3. The Ocean Floor - The Vast World Ocean
Origin 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 CO 2
-The CO 2 and other gases formed the Earth's atmosphere
-As the Earth cooled, the water vapor condensed,
forming the oceans.

4. he Blue Planet
arth is known as the " Blue Planet" because ~71% 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 (H 2 O level rises) and Glaciers expanding
(H 2 O 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 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. Use pages 401-406 in your textbook,
defining each term and labeling the diagrams.
“See” the Ocean Floor
Continent
Trench
Continental
Mid-Ocean
Margin
Ridge
Continental
Rift Valley
Shelf
Volcanic Island
Continental Fringing Reef
Slope
Barrier Reef
Continental Rise
Atoll
Submarine
Define but
do not label:
Canyon
Seafloor Spreading
Abyssal Plain Hydrothermal Vent
Seamount

12. Work on Worksheet

13. Fringing- 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)
Types of Coral Reefs

14. FRINGING REEF
ATOLL REEF
BARRIER REEF

16. 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?
Word bank
(some answers are
here, but not all of
them!)
Continent
Abyssal plain
Seamount
Volcanic island
Submarine canyon
Continental shelf
Continental margin
Guyot
Trench
Mid-ocean ridge
Continental rise
Rift valley
Continental slope

17. 1.
2.
3.
4.
5.
6.
7.
8.
9.
Pacific
Indian
Any of these: meteorite, comets, volcanoes
Sound Navigation and Ranging
3 points: IN ORDER:
Cont.Shelf, Cont.Slope, Cont.Rise
ANSWERS!!!
Abyssal Plain
Fringing Reef
Guyot
Trench

18. Brainpop-Ocean Floor
Continental Margin
(shelf, slope, rise)
Inter-Tidal Zone
Area of shoreline
between high and
low tides
Con
tinen
tal sh
e
High Tide
Low Tide
lf
~200m
Photosynthetic Zone: light penetrates for
photosynthesis. Up to 150 m (488ft)
nta
ne
nt i
Co pe
Slo
THERMOCLINE ~200-100ft
Bathyal Zone: Darkness
l
MAJOR
OCEANIC
ZONES
Co
n
Benthic Environment:
tine
Ocean bottom or floor
nta
l Ri
se
4000 m
Abyssal Zone: 4000-6000m
Abyssal Plain
>6000m
Hadal Zone

20. Work on the Review &
Reinforcement WKST
“Physical Properties of the
Ocean Life Zones”

21. 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.
• 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

22. 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.

23. OCEAN 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.

24. 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.

25. 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

26. 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.

27. The Dynamic Ocean
OCEAN CIRCULATION & WAVES AND TIDES
Ocean Waves
4 Movements of the Ocean: Waves, Tides, Currents & Upwellings
WAVES =
Rhythmic movement that carries energy through space or matter
- 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.
(water)

28. ve Measurements:
ighest point = crest. Lowest point = trough.
istance from Crest to Trough = wave height.
istance from Crest to Crest (or trough to trough)
wavelength.
Wave speed increases with wavelength.

29. - 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

30. 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

31. Causes of Tides:
Discovery EdTides
Brainpop 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

32. Warm-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?

33. Ocean Currents- Discovery Ed
Brainpop Ocean Currents
OCEAN CURRENTS
CURRENT = 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.

34. 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.

35. UPWELLING
· Water not only moves horizontally (currents) but it
also moves vertically.
· UPWELLING = upward motion of ocean water
· Cold water flows upward to replace
warm surface water blown out to
sea by offshore winds.
· They mainly occur on western coasts.
· Rich in nutrients, thus supporting lots of marine life.

40. BEACHES
Wave movement toward the shore often builds up a strip
of sediment at the coastline called a beach.
Beaches are composed of whatever sediment is
available, but most beaches are composed of sand.

41. 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.

42. Abrasion
Sawing and grinding action of rock fragments in water.

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

44. Longshore Transport
• Current that flows parallel to the shore and moves large
amounts of sediment.
• Caused by bending of waves.

45. EROSIONAL
FEATURES

46. • During storms waves can be much more powerful than normal.
Created by L. Zimmerman

47. During these times
the beach tends to
erode more and the
sand is carried back
into the ocean.
There it is usually
deposited as
underwater bars
parallel to the shore.
Created by L. Zimmerman

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

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

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

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

52. DEPOSITIONAL
FEATURES

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

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

55. Tombolo
Ridge of sand that connects an island to the
mainland or to another island

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

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

58. 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)

59. STABILIZING
THE SHORE

60. Groin
Barrier built at a right angle to shore to keep sand in place

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

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

63. Seawalls

65. 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

70. The Barrier Islands on the
Outer Banks