ERESE Master Document    Index:

• Teachers Log

• CP0001 Expedition - Cruise Planning

• M00001 Simple Seafloor Spreading (Reykjanes Ridge)
• M00002 Complex Seafloor Spreading (Vancouver)
• M00003 Geological Time Scale
• M00004 The Earth's Magnetic Field
• M00005 Plate Motion -- Geometry on a Sphere
• M00006 Magnetic Reversals
• M00007 Oceanic Crust
• M00008 Seamounts
• M00009 Hotspots
• M00010 Biomediation of Lavas
• M00011 Planetary Magnetics
• M00012 Evolution of the Earth's Magnetic Field
• M00013 Tectonic Plates
• M00014 Pangaea
• M00015 Reading Maps
• M00016  Convergent Boundaries
• M00017  Divergent Boundaries
• M00018 Strike Slip Boundaries

Students will be challenged within this interactive, inquiry based lesson to first sample and then explore real data in an effort to 1) identify key sea floor features, including mid-ocean ridges, trenches, ocean basins, seamounts, continental shelf and slope; and then 2) sample data collected during a trans-Atlantic voyage designed to determine whether the Atlantic Ocean, and consequently the continental land masses that border it are changing over time. Students will “discover” the action occurring along ocean ridges and trenches and identify each as spreading and subduction centers respectively using actual data collected during their ocean voyage.

Summary: To introduce students to evidence of sea floor spreading and to provide a reasonable model for the apparent jigsaw puzzle fit of the continents.

Distribute the following situation statement to students as a written document. Provide students with time to read and process this information.

Situation statement (Case Study): Congratulations! You have been selected to be a member of the S.S. Titanic oceanographic research team. As a member of this elite team, you have been charged with conducting a study of the Atlantic Ocean. Ever since the continents that surround the Atlantic Ocean were accurately mapped in the 1500's, people have wondered why the Americas seem to fit the African continent like pieces of a jigsaw puzzle. Your teams goal is to study various types of data and find a plausible explain for the apparent jigsaw puzzle fit exhibited by the continents of North America, South America and Africa. It might be reasonable to ask "Were these continents once connected? If so, how did they separate and move to their present locations?"

To solve this mystery, your scientific expedition will travel across the Atlantic. Your journey will take you from New York City to the coast of West Africa (see map below - paper handout - provide link to map here). During the course of your expedition, your team will collect and analyze several types of data in an effort to solve the mystery.

Prior to embarking upon your scientific expedition, your team needs to prepare by studying the ocean floor. Before beginning your study, you should discuss with your group what you expect the ocean floor to look like - NO resources may be used at this time. After you document your expectations, you may use iView 3d (a software tool) to explore the ocean floor.

As you study the ocean floor, you should identify all the sea floor features your journey will take you over or pass by. As you explore the sea floor, record any (and all) questions that arise about what you are seeing.

Hint: A good model for locating features is to mark their location using each features latitude and longitude, and its proximity to the nearest city, state or island. For example, if you identify a feature near the Bahamas that needs to be identified, you would report the features at a latitude of 27.3ºN, 73.2ºW and you would indicate that the feature is approximately 300 km Northeast of Grand Bahama Island. (Note: Think about what the “N” and “W” labels mean – if you're unsure, you may receive assistance at: http://academic.brooklyn.cuny.edu/geology/leveson/core/linksa/latlong_menu.html).

To help you identify key sea floor features, you may find the diagram at the following link helpful:

http://oceanworld.tamu.edu/resources/ocng_textbook/chapter03/Images/Fig3-6.html.

Note to teacher: provide students with graph paper to create a cross-section of the sea floor and to label key sea floor features.

Teacher circulates from group to group to assist in identifying key features.

Students should be encouraged to use the diagram at: http://oceanworld.tamu.edu/resources/ocng_textbook/chapter03/Images/Fig3-6.html to assist with identification of sea floor features.

Encourage students to record scientific observations and questions regarding the sea floor features.

Encourage students to be as quantitative as possible. For assistance, they may use the ocean depth color key. (Provided with iView 3d Atlantic.scene file). Provide students with graph paper and encourage them to develop a cross-section map of the ocean floor. (A preliminary activity on cross-sections may be required here. Suggestions include:

provide suggestions here for a cross-section introductory activity

Allow students approx. 30 - 45 minutes to create a hand drawn cross-section diagram of the seafloor and label elevations. Encourage the use of a wall map of the world to determine horizontal distance also.

Provocative Phenomenon: The Atlantic scene within iView 3d. (note to ERESE staff: post this scene on a server at some point.)

Anticipated student observations and questions:

Continental shelves are situated adjacent to continental landmasses. The continental shelves are wider along the U.S. east coast when compared to the coast of West Africa.

-->Why do continental shelves vary in width?

Continental slopes are steep regions that connect the shelf to the ocean floor.

Mid-ocean ridges are actually a massive underwater (mostly) mountain chain.

-->Why do mid-ocean ridges exist?

Trenches are the deepest parts of the ocean.

-->What causes trenches to form?

-->What causes seamounts to form?

-->Have the identified features always existed or by what means did they form?

-->If these features have not "always existed", how old are they? Do their ages vary? If so, which are the youngest? Oldest?

Teacher may need to prompt to elicit this defining question (see prompts below): How might all these features be connected? OR Is there an overall process that can collectively explain the presence of some or all of these features?

Teacher may need to ask whether all the observed features formed randomly.

Teacher may prompt students by asking whether ridges and trenches are connected in some way.

Encourage students to ask "why" or "how" questions.

After students have exhausted questions, teacher identifies questions that can be addressed (according to the time, expertise level, or data available.)

Narrow questions down to the key question that will be the subject of the upcoming field experiment, and subsequent data collection and analysis.

Research question: Is it just coincidence that the coastlines of North America, South America and Africa all seem to have a jigsaw puzzle fit? Is there a unifying theory that can explain this observation as well as the presence of the observed sea floor features.

Researchable Hypothesis: Using a variety of datasets (or types of data) students will explore the ocean basins and discover the mechanism that has led to sea floor spreading and most of major sea floor bathymetric features.

Suggested content lessons:

1) Extend student created observations for the Atlantic to other oceans. Note the existence of the same seafloor features in other ocean basins.

Misconception alert: mid-ocean ridges are NOT always in the middle of the ocean!

2) Display a map of Mars, challenge students to identify 'earthlike seafloor features' on Mars.

-What examples can you find to...?

-How would you organized the following to show...?

-What inference can you make?

-What evidence can you find?

-How would you test?

"After identifying the sea floor features discussed earlier, you are ready to embark upon your expedition. You should begin by reviewing the researchable question identified during our debriefing. You may also wish to consider the following questions as a starting point for your research:

1) Were the continents ever connected? Cite evidence or data to support your answer.

2) If the sea floor has spread over time, how can the data be used to support this position?

3) Can you determine over what period of time this process has occurred and at what rate?"

Introduce students to the various types of data available within "Our Dynamic Planet" (ODP) (Source: William Prothero, UCSB), including depth, magnetic anomalies , heat flow data, earthquake data , volcanoes , and sea floor age.

Using ODP, students can draw transects that will cover their exploration route. (Again - refer to map of the expedition.) Once a transect is drawn, the various types of data listed above can be explored in a variety of manners. ODP presents the data in a simplified GIS interface as well as graphically.

Note: For each data type, provide background information on how the data is acquired. Background information may be presented as a "whats this" document or in the form of a quicktime video. The video, ideally is a 3-5 minute briefing conducted by an oceanographic expert from SIO. The background briefing needs to explain to the student how the various data is used to draw conclusions. For example, students will need to know how to read and interpret magnetic anomalies; students will need to understand how to interpret heat flow data – as I understand it, heat flow increases as you approach a mid-ocean ridge, therefore, it indicates something significant going on in that region; earthquake / volcano data – a quicktime video explaining that this kind of action is often indicative of plate movement or at least something going on deeper within the Earth that results in changes in the surface (whether or not that surface is above sea level.)

The model I'm using here calls for the students to use the quicktime videos on a ‘need to know’ basis. As noted above, the videos need to explain and illustrate how the various measurements (depth, magnetic anomalies, and heat flow data) are gathered.

Using the heat flow data, movement of magma (as indicated through a quicktime video) should be detected near the mid-ocean ridge. Further evidence of heat flow can be detected by studying volcanic activity. (A qt movie discussing causes for volcanoes would be appropriate here.

Students will work in teams of 3-4 during this project. Each will become a specialist in a different area – one using the heat flow data; one using volcano data; one using earthquake data; one using magnetic anomaly and sea floor age data. Students will sample the data at sampling points available to them and search for patterns.

With support from the quicktime videos, the following images from the ERDA database, and the teacher, students will be encouraged to piece together the significance of their findings.

Additionally provide a series of charts and diagrams cataloged in the ERDA database:

1. Illustration of Magnetic Anomalies Forming Along Mid-Ocean Ridge

m00001.magnetic.reversal.jpg Magnetic reversals along mid-ocean ridges

http://earthref.org/cgi-bin/ado.cgi?n=209&dbms=ERDA

2. Model of a MidOcean Ridge

m00001.b.w.magnetic.stripes.xsection.gif

http://earthref.org/cgi-bin/ado.cgi?n=215&dbms=ERDA

3. Relationship of Temperature and Earthquakes in a Downgoing Slab

m00016.d3.temp.earthquakes.subduction.gif

http://earthref.org/cgi-bin/ado.cgi?n=327&dbms=ERDA

***NOTE to developers: can this diagram be modified to illustrate where the trench should be??

4. Map of North American Plate and Eurasian Plate diverging over Iceland

m00013.i3.plates.iceland.gif

http://earthref.org/cgi-bin/ado.cgi?n=297&dbms=ERDA

5. Display of Magnetic Stripes Off the Coast of Iceland

m00001.heirtzler.anomalies.jpg

http://earthref.org/cgi-bin/ado.cgi?n=207&dbms=ERDA

6. Magnetic Polarity and Ocean Depth Plotted Against Longitude Along the Reykjanes Ridge

m00001.d5.aadi0001733fig03.jpg

http://earthref.org/cgi-bin/ado.cgi?n=240&dbms=ERDA

Note to educator: Students will require assistance interpreting this image.

Students are to sample and collect data within the Our Dynamic Planet interface and use the charts and diagrams from the ERDA database to address the researchable question and the additional 'guiding questions' posited above within this section.

Teacher should circulate from team to team, querying progress, asking probing questions, assisting students in the use of the software interface, as well as with the collection of data.

Possible Content Lessons:

1. Students will be provided with 'how to' sheets or 'whats this' sheets along with quicktime videos (initially from the Our Dynamic Planet CD, later ideally from SIO researchers as described above in this section) - these videos will serve as self-directed lessons that students seek as they work through their data collection and analysis.

2. Teacher may decide to create 'need to know' (mini) lessons for students who self-select to attend the brief lecture. Topics may include interpretation of heat flow data; origin and use of magnetic anomalies, as well as the significance of volcanic activity. These lectures, generally less than 10 minutes in length may involve one or two teams of students (or parts of teams who then report back to their team-mates.) Students become increasingly responsible for their own time management - a task worthy of teaching in its own right!

Students will prepare written and oral explanations of all graphs, charts, and diagrams that they create and or choose to use.

Content lessons: Provide mini lesson opportunities on

1) Use of the composer tool

2) analysis (interpretation) of graphs, charts and diagrams

Formative assessment: Quality of graphs produced. Documentation provided illustrating the necessary components for a quality graph or student produced visual.

Summative assessment: Assess quality of presentations and follow up discussion. Students provided with a rubric to facilitate preparation.

Major areas to evaluate include:

--> Students use data to identify mid-Atlantic Ridge as a spreading center. Supporting data should include identifying the mid-Ocean ridge as a site where new seafloor is produced as the youngest seafloor rock is found there. Additionally, heat flow data reveals the presence of near-surface (ocean floor) magma, this suggests possible volcanic activity. Further evidence can be cited by the presence of volcanos as presented in the GIS interface within ODP. Evidence of movement can be cited by the concentration of shallow earthquakes along the ridge itself. Finally, using magnetic anomaly stripes, students can confirm increasing seafloor age as one proceeds away from the ridge axis.

--> Students use data to identify trenches as sites where seafloor is being 'reintegrated' into the lower crust/upper mantle. Supporting data should include identifying trenches as sites of the oldest and deepest seafloor sediments/rock; deeper earthquakes than those observed at the ridges - indicative of subduction.

--> Students should identify where the continental shelf is and what process created it. Further, their observations should note that the continental shelf varies in width from "old" coastlines (where the seafloor is older) to "younger" coastlines where the seafloor is younger. A goal here would be to have students connect the idea that the older the seafloor sediment, the longer the coastline has been allowed to accumulate sediment from rivers and consequently, the wider the continental shelf.

--> Students should discuss each tool used to collect the various types of data used to draw conclusions in their oral presentation.