Question of the DayQuestion of the day:

What could cause a tsunami besides an earthquake?

OutlineQoDPass back yesterday’s QoD (everyone =

10/10)Syllabus correction: Start with Chapter 14Quick Experiment: SedimentLunchBathymetry

Quick Experiment: SedimentI’ll Assign Groups1. Everyone make a table in your science notebook:

2. Measure and record the height of the water (“Distance” in cm)

3. Practice using the stopwatch 3 times, then:4. Gently pour sand into water, measure and record

time for most sediment to settle5. Repeat step 3 for clay6. Calculate the settling rate in cm/s for sand and

clay

Material

Distance (cm)

Time (s)

Rate (cm/s)

Sand

Clay

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?

Quick Experiment: Sediment

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 ArcticPacific is the largest and deepest (average

depth ~4,000 meters)  

Ocean Basins

Arctic Ocean

“Topography”

Represents the Earth’s 3-dimensional land surface on a 2-dimensional map

But What About Under Water?

BathymetryBathymetry- 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

BathymetryBathymetry- 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 AirSpeed of sound in air ~ 340 m/shttp://www.youtube.com/watch?

v=jqdbCGzmCfghttp://www.youtube.com/watch?

v=V1w2DNp3Lp4&feature=relatedhttp://www.youtube.com/watch?

v=Igy_MYJpVcQ&feature=related

Speed of Sound in the Ocean

Remember: speed of sound in air ~ 340 m/s

Speed of Sound in the Ocean vs. Depth

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.

QuestionA ship sends out a SONAR sound and begins recording time. The microphone records the information shown on the graph at the right:

Approximate the ocean depth in your science notebook

Time (s)

Sig

nal (

Am

plitu

de [

Db]

)

0 1 2 3 4

Microphone Signal vs. Time

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.

SubmersiblesSubmarines: 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 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

Homework Answers1. Nearly 71 percent of Earth’s surface is covered by

oceans, 29% by land2. 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. Three types of technology to study the ocean floor are sonar, satellites and submersibles

5. 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.

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.

7. The deep ocean is dark, cold and under high pressures.8. 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 deepThese 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 FloorOcean 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 LandformsAbyssal 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 ~1000-4000m=3300-13,200 feet wide.

Hydrothermal Vents: Form along ridges and pump out mineral rich hot water.

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?

HomeworkPg. 405 AssessmentQuestions 1-7 and the Writing in Science

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

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