Question of the Day
 Question of the day:
What could cause a tsunami besides an earthquake?
Outline
 QoD
 Pass back yesterday’s QoD (everyone = 10/10)
 Syllabus correction: Start with Chapter 14
 Quick Experiment: Sediment
 Lunch
 Bathymetry
Quick Experiment: Sediment
I’ll Assign Groups
1. Everyone make a table in your science notebook:
Material
Distance (cm)
Time (s)
Rate (cm/s)
Sand
Clay
2. Measure and record the height of the water (“Distance” in
3.
4.
5.
6.
cm)
Practice using the stopwatch 3 times, then:
Gently pour sand into water, measure and record time for
most sediment to settle
Repeat step 3 for clay
Calculate the settling rate in cm/s for sand and clay
Quick
Experiment:
Sediment
Answer the following questions in science notebook:
1. What is the relationship between sediment size and
settling rate?
2. Both of these sediments are carried to the ocean by rivers.
Which sediment would be closest to the coast and which
would be found farther away and why?
Chapter 14: The Ocean Floor
Oceanography: Combines the sciences of geology,
biology, chemistry and physics to study our oceans.
~70% of the Earth is covered by H2O
Four main ocean basins: Pacific, Atlantic, Indian, and
Arctic
Pacific is the largest and deepest (average depth
~4,000 meters)
Ocean Basins
Arctic Ocean
“Topography”
Represents the Earth’s 3dimensional land surface
on a 2-dimensional map
But What About Under Water?
Bathymetry
Bathymetry- measures the depths and charts the
floors of water bodies.
HMS Challenger-first to study bathymetry in parts of
all the oceans except the Arctic Ocean
A brief aside:
George Vancouver, 1792
Bathymetry
Bathymetry- measures the depths of the ocean and
charts the seafloor.
HMS Challenger-first to study bathymetry of all the
oceans except the Arctic Ocean
144 miles of
“sounding rope”
and 12 miles of
piano wire
Modern Bathymetry Tools
Sonar: Sound, Navigation,
And, Ranging. Sends a sound
wave to the seafloor where it
is bounced back to the ship
above. Microphone on ship
records echo. Measure time.
• Single beam
• Multibeam
Sonar mostly only used for
navigation these days
Speed of Sound in Air
 Speed of sound in air ~ 340 m/s
 http://www.youtube.com/watch?v=jqdbCGzmCfg
 http://www.youtube.com/watch?v=V1w2DNp3Lp4&fe
ature=related
 http://www.youtube.com/watch?v=Igy_MYJpVcQ&fea
ture=related
Speed of Sound in the Ocean
Speed of Sound in the Ocean vs. Depth
Remember: speed of sound in air ~ 340 m/s
Modern Bathymetry Tools
Sonar: Sound, Navigation,
And, Ranging. Sends a sound
wave to the seafloor where it
is bounced back to the ship
above. Microphone records
echo.
Question
Approximate the ocean
depth in your science
notebook
Microphone Signal vs. Time
Signal (Amplitude [Db])
A ship sends out a SONAR
sound and begins recording
time. The microphone
records the information
shown on the graph at the
right:
0
1
2
3
Time (s)
4
Bathymetry
Bathymetry Tools – More Modern
Geostationary satellites
measure the height of
the ocean surface.
Height of ocean surface
varies as a result of
tides, waves etc.
Height ALSO varies as a
result of gravitational
differences from
underwater landforms.
Submersibles
Submarines: Manned and unmanned submersibles are able to
take recordings (and samples) at very deep depths.
1st sub to be used was in 1934 off the coast of Bermuda
went to 923m= 3,046 feet.
“Alvin” can dive to 4,000m= 12,000 feet
“Sea Cliff 2” can dive to 6,000m=19,800 feet.
Homework assignment
 Bring in a Shoebox for next week’s lab!
 Copy the information from someone’s
science notebook into yours if you didn’t
have one today (no more copying after
today!)
 Problems 2, 6, 8 on page 400 of textbook
Homework Answers
1.
2.
Nearly 71 percent of Earth’s surface is covered by oceans, 29% by land
Pacific, Atlantic, Indian and Arctic
Pacific is the largest
Indian is in the Southern hemisphere
3.
Topography of the ocean floor is as diverse as land.
Mid ocean ridges, trenches and abyssal plains are three features
4.
5.
6.
7.
8.
Three types of technology to study the ocean floor are sonar,
satellites and submersibles
Sonar works by transmitting sound waves to the ocean bottom A
receiver receives the echo reflected from the ocean bottom and a
clock measures the time it takes for the sound wave to travel to the
ocean bottom and back.
Submersibles and satellites are used to find out more about the
ocean’s topography. Satellites use remote sensing of the surface.
Subs travel to deep areas and record data.
The deep ocean is dark, cold and under high pressures.
4.5/2 x 1500 m/s = 3375 m
Three Major Ocean Areas
Three Major Areas for Study: Continental Margins,
Ocean Basin, Mid-Ocean Ridges.
Continental Margins: Pacific is volcanic, constantly
changing and small in comparison with the Atlantic
margin which is large and composed of undisturbed
sediment.
Continental Shelf: Sloping area that extends from the
shoreline and is ~80m=264 feet wide and 130m=429
feet deep
These areas have reservoirs of oil, natural gas, sand
and gravel that can be used commercially.
Continental Slope: The end of the continental shelf; ~5
degrees to over 25 degrees. These areas are known
for having turbidity currents that transport
sediments down the slope and into canyons.
Continental Rise: Where the continental slope merges
into a gradual incline.
Ocean Basin Floor
Ocean Basin Floor: This area encompasses the Continental
Margin to Mid-Ocean Ridges and accounts for 30% of
Earth’s surface.
Trenches: Long, narrow, deep areas that are often
associated along convergent plate margins Ex: Marian
Trench: 11,022m=36,373 feet deep at the deepest spot.
Ocean Floor Landforms
Abyssal Plains: Deep, flat areas that are composed
mostly of sediment. The Atlantic Ocean has the
most substantial.
Sea Mounts and Guyots: Active/Extinct volcanic
peaks that rise out of the water are Sea Mounts
and extinct volcanoes that are below the surface
with an eroded flat top are called Guyots.
Mid-Ocean Ridges
Mid-Ocean Ridges: Occur
near the center of most
oceanic basins and result
from seafloor spreading
and divergent plate
boundaries. Longest
feature on Earth extending
70,000km long and ~10004000m=3300-13,200 feet
wide.
Hydrothermal Vents: Form along
ridges and pump out mineral
rich hot water.
Explaining Coral Atolls- Darwin’s Hypothesis
Read pg. 406
Draw and label in your notebook the formation of coral
atolls.
Describe the steps using the terms fringing reef, barrier
reef and coral atoll.
Answer the following:
What does Darwin’s hypothesis of atoll formation imply
about the relationship between the rate of growth of
coral reefs and the rate of subsidence of volcanoes?
According to the theory of plate tectonics, what would
cause a volcano to sink below the ocean surface?
Which is Which?
Homework
 Pg. 405 Assessment
 Questions 1-7 and the Writing in Science
 Answer in complete sentences, will be stamped next
class for full credit
Homework answers
What are the three major regions of the ocean floor?
1.
Continental margins, ocean basin floor, mid-ocean ridge
2.
How do continental margins of the Atlantic differ from the Pacific?
2. Atlantic has thick layers of undisturbed sediment and very little volcanic
activity. Pacific the ocean crust is being pushed beneath the continental
leaving narrow margins with a lot of volcanic/earthquake activity.
3.
What are trenches and how are they formed?
3. Trenches are long creases in the seafloor and are formed at convergent
zones (one plate sliding under another)
4. What are abyssal plains and how are they formed?
4. They are deep, flat features that are formed as sediments from coastal
regions are transported out to sea and settle to the ocean floor.
5.
What is formed at mid-ocean ridges?
5. New ocean floor
6. Seamounts vs. Guyots:
6. Seamounts are underwater volcanoes that do not reach the surface of the
water. Guyot is a volcanic island that has eroded and subsided below the
water’s surface.
7.
Describe how turbidity currents are related to submarine canyons.
Turbidity currents have dense mud and water that flows downn the
continental slope. As the current flows down it further erodes creating a
submarine canyon.
1.
Oceanfloor
 Check on your box and see if it is drying-you may have
to leave the lid off over the weekend
 Sometime during the period set up the Quick lab
(Next slide) pg. 412 Use plastic cup
 Read the Ocean floor and Diver Overboard packets
and answer the questions in your notebook. 1
fathom=6 feet
 Discuss three interesting things you learned from the
packets with someone at your table. Write down three
things that they told you in your notebook
Quick Lab
Follow the instructions on pg 412 for the quicklab
Evaporative Salts except poor your mixture into the
plastic cup and measure the plastic cup with the salt
(don’t forget to weigh the empty cup).
Sedimentation
Sediments on the floor can be up to 10m=33feet deep.
Types of Sediments: Terrigenous, Biogenous, or
Hydrogenous.
Terrigenous: Originates on land and is mostly mineral
grains
Biogenous: Biological origins, shells, skeletons, and algae.
Hydrogenous: Minerals that recrystalize directly from
ocean water.
Biogenous:
Calcareous Ooze: Calcium carbonate derivatives that
form a thick like mud yet completely dissolve before
they reach 4500m=14,850 feet.
Siliceous Ooze: Primarily diatom shells yet can also
include radiolarians.
Which is which?
Homework
Section 14.3 Assessment pg. 409
Questions 1-6 and the Connecting concepts
 Answer in complete sentences, will be stamped next
class for full credit
Homework Answers
1.
2.
3.
4.
5.
Terrigenous, biogenous and hydrogenous are the three types of
ocean floor sediments.
Terrigenous sediment is made of mineral grains weathered
from continental rocks.
Biogenous sediment is made of shells and skeletons of marine
animals and algae.
Minerals crystallize directly from the water through chemical
reactions to form hydrogenous sediment.
Calcareous and siliceous ooze both have the consistency of
thick mud and are biogenous. Calcareous is formed form the
calcium carbonate of sea animals and is only found in depths
less than 4500 meters. Siliceous ooze is formed from the
siliceous (silica-based) parts of organisms like diatoms and
radiolarians..
Energy Resources
Primary Energy Resources: Oil & Natural Gas
Derived from organisms that were buried before they
were fully decomposed. After millions of years of
heat from the Earth’s core and pressure from the
depth.
Gas Hydrates-made of water and natural gas,
most common form is methane. Tend to break
down when brought to the surface.
Why doesn’t the burning gas hydrate burn the hands of a person
holding it?
As the gas hydrate slowly
dissociates it releases
methane from its surfaces.
Being less dense than air
it quickly rises and is
concentrated above the
sample, confining the
flame to the region above
the person’s hands.
Other Resources
Sand and Gravel
--landfill, concrete and
beaches
Manganese Nodules
-- have manganese,
iron, copper,nickel
and cobalt
Evaporative salts
--produces about
30% of the world’s salt
Homework
Pg. 413 Section 14.4 # 1-8 and Connecting Concepts
Homework answers
1.
2.
3.
4.
5.
6.
7.
8.
Oil and Natural Gas are the main energy resources from the ocean
Gas hydrates are formed when bacteria break down organic matter in
seafloor sediments. The bacteria produce methane gas with some
ethane and propane. These gases are trapped inside the water
molecules.
Ocean spills and gas hydrates breaking down are two drawbacks of
harvesting energy from our oceans.
Other resources are sand and gravel, evaporative salts and
manganese nodules.
Evaporative salts are used to preserve foods, dye fabric, de-ice roads
and agriculture.
Manganese nodules are lumps of manganese, iron, copper, etc that
form around grains of sand.
As we improve technology, we can retrieve resources more efficiently.
Suspended sediments can effect light which effect photosynthesis
and filter feeders.
Connecting concepts
Sand and gravel are coarse sediments so they settle out more quickly.
Extra “Stuff”
 Link to NOAA Port Orchard Nautical Chart
 http://www.charts.noaa.gov/OnLineViewer/18440.sht
ml