Question of the Day
Name the three sections of the
continental margin
Compare your answers on the
homework with your neighbor
(#2, #6 and #8 pg 400)
Outline
 QoD
 Brief note-taking on the remainder of the ocean floor
 Begin ocean floor laboratory (choose own groups of 2)
 Cleanup
 Tsunami video
Homework Answers
#2: Atlantic, Pacific (largest), Indian (southern hemisphere),
Arctic
#6: 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.
Satellites
Submersibles
Can produce detailed maps
of large areas of the ocean
floor
Can collect water/sediment
samples and video
#8: 3,375 m
4.5/2 x 1500 m/s = 3375 m
Ocean Basin Floor
Ocean Basin Floor: This area encompasses the Continental
Margin to Mid-Ocean Ridges and accounts for 30% of
Earth’s surface. Notable features include trenches,
abyssal plains, and seamounts and guyots.
Trenches
Trenches: Long, narrow, deep
areas at convergent plate
boundaries
Examples:
1) Cascadia Subduction Zone.
2) Marianas Trench:
11,022m=36,373 feet deep;
the deepest place on earth.
Exaggerated Cross section of a trench
Abyssal Plain
Abyssal Plains:
 Deep (3,000-6,000 m)
 Flat (ludicrously flat)
 Composed of sediment from turbidity currents
or from settling from ocean water
 Unexplored
Seamounts and Guyots
 Seamount: an underwater volcano on the “way up”
 Guyot: a wave-eroded, flat topped, dormant volcano
Ocean Basin Floor
Ocean Basin Floor: This area encompasses the Continental
Margin to Mid-Ocean Ridges and accounts for 30% of
Earth’s surface.
Mid-Ocean Ridges
Mid-Ocean Ridges: Occur
near the middle of most
oceanic basins and results
from seafloor spreading.
Longest feature on Earth
extending 70,000km long
and ~1000-4000m=330013,200 feet wide. Located
at divergent plate
boundaries.
Hydrothermal Vents: Form along
ridges and pump out mineral
rich hot water.
Mid Ocean Ridges
Mid Ocean Ridge
Ocean Lab
 Groups of 2
 Each group:
 1 Shoebox (plug holes with carboard/tape if necessary)
 Graph paper
Ocean Lab Instructions Part I
 Each group:
 1 Shoebox (plug holes with cardboard and tape as
necessary)
 Graph paper from me
 Choose 2 or 3 ocean floor shapes to model
 Continental rise, slope and shelf…?
 Submarine canyon on a continental slope?
 Ocean trench?
 Seamount(s)?
 Guyot(s)?
 Mid-ocean ridge?...
 Combination??? Other???
 Try NOT to make your model “square” to the shoebox
Ocean Floor Shapes
Ocean Lab Instructions Part II
Each group:
1. Mix 2 scoops flour, 2 scoops salt together in
container
2. Add 1 scoop water; mix until stiff putty
3. Build your model in the shoebox. Remember,
don’t need to waste putty by creating flat areas.
Use ocean floor drawings as a guide
4. Put your names on side of box (outside)
5. Tape the lid on your box
6. Tape grid paper to top of box
7. Put all boxes along south wall
Cleanup
Drones:
 “Dry” flour and salt group (sweep counter and floor; tidy up
salt/flour area)
 “Water” group (use water and paper towels as necessary on
counter and floor; leave dry)
 Bucket group (clean all buckets and put back on south wall)
 Spoon/spatual group (clean all spatulas / spoons and put back
on south wall)
Management
 See me
Homework
 Read page 407-409
 Answer #2-#4, #6 on page 409
 Can either take science notebook home and write in
answers or,
 Leave science notebook here and write answers on
separate sheet and tape into science notebook later
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
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
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?