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)

OutlineQoDBrief note-taking on the remainder of the

ocean floorBegin ocean floor laboratory (choose own

groups of 2)CleanupTsunami 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.

#8: 3,375 m 4.5/2 x 1500 m/s = 3375 m

Satellites Submersibles

Can produce detailed maps of large areas of the ocean floor

Can collect water/sediment samples and video

Ocean Basin FloorOcean 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.

TrenchesTrenches: Long, narrow,

deepareas at convergent plate

boundariesExamples: 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 PlainAbyssal Plains: Deep (3,000-6,000 m)Flat (ludicrously flat)Composed of sediment from turbidity

currents or from settling from ocean waterUnexplored

Seamounts and GuyotsSeamount: an underwater volcano on the

“way up”Guyot: a wave-eroded, flat topped, dormant

volcano

Ocean Basin FloorOcean 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=3300-13,200 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 LabGroups of 2Each group:

1 Shoebox (plug holes with carboard/tape if necessary)

Graph paper

Ocean Lab Instructions Part IEach group:

1 Shoebox (plug holes with cardboard and tape as necessary)

Graph paper from meChoose 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 IIEach group:

1. Mix 2 scoops flour, 2 scoops salt together in container

2. Add 1 scoop water; mix until stiff putty3. 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 box6. Tape grid paper to top of box7. Put all boxes along south wall

CleanupDrones:“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)

ManagementSee me

HomeworkRead page 407-409Answer #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 answers1. What are the three major regions of the ocean floor?

1. Continental margins, ocean basin floor, mid-ocean ridge2. 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.

OceanfloorCheck on your box and see if it is drying-you may

have to leave the lid off over the weekendSometime during the period set up the Quick lab

(Next slide) pg. 412 Use plastic cupRead 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 LabFollow 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).

SedimentationSediments 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 grainsBiogenous: 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?

HomeworkSection 14.3 Assessment pg. 409Questions 1-6 and the Connecting concepts

Answer in complete sentences, will be stamped next class for full credit

Homework Answers1. Terrigenous, biogenous and hydrogenous are the

three types of ocean floor sediments.2. Terrigenous sediment is made of mineral grains

weathered from continental rocks.3. Biogenous sediment is made of shells and skeletons

of marine animals and algae.4. Minerals crystallize directly from the water through

chemical reactions to form hydrogenous sediment.5. 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 ResourcesPrimary Energy Resources: Oil & Natural GasDerived 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 ResourcesSand and Gravel--landfill, concrete and beachesManganese Nodules-- have manganese, iron, copper,nickel and cobaltEvaporative salts--produces about 30% of the world’s salt

HomeworkPg. 413 Section 14.4 # 1-8 and Connecting

Concepts

Homework answers1. Oil and Natural Gas are the main energy resources from the

ocean2. 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.

3. Ocean spills and gas hydrates breaking down are two drawbacks of harvesting energy from our oceans.

4. Other resources are sand and gravel, evaporative salts and manganese nodules.

5. Evaporative salts are used to preserve foods, dye fabric, de-ice roads and agriculture.

6. Manganese nodules are lumps of manganese, iron, copper, etc that form around grains of sand.

7. As we improve technology, we can retrieve resources more efficiently.

8. Suspended sediments can effect light which effect photosynthesis and filter feeders.

Connecting conceptsSand and gravel are coarse sediments so they settle out more

quickly.

Extra “Stuff”Link to NOAA Port Orchard Nautical Charthttp://www.charts.noaa.gov/OnLineViewer/

18440.shtml

Homework assignmentBring 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 HypothesisRead pg. 406Draw 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?