Granite Helps Scientists Piece Together Rodinia

If you’ve taught plate tectonics at the middle school level, you’re probably quite familiar with the supercontinent Pangaea. But did you know that Pangaea was not the only supercontinent in earth’s history – just the last to date? Millions of years before Pangaea, another supercontinent known as Rodinia united all of earth’s landmass in an unusual configuration. While we tend to think of Pangaea as the “starting point,” earth’s land and ocean basins have been continually shaped throughout geologic time through a supercontinent cycle.

While Pangaea certainly gets more press, Rodinia was the star of an article in the July 11, 2008 edition of Science. As summarized in a National Science Foundation News release, John Goodge’s team was collecting geologic specimens in the Transantarctic Mountains when they discovered a single granite boulder atop Nimrod Glacier.

Andrew Barth (L) and Devon Brecke (R), collecting glacial moraine samples in the Miller Range of the Transantarctic Mountains. Photo courtesy of John Goodge, University of Minnesota.

Subsequent chemical and isotopic tests indicated that the boulder was strikingly similar to a belt of igneous rock running through the southwestern United States. These similar chemical and isotopic signatures provided support for the SWEAT (southwest United States East Antarctica) hypothesis, which states that East Antarctica was connected to the southwestern United States approximately one billion years ago, as part of the global supercontinent Rodinia.

The supercontinent Rodinia as it began to break up approximately 750 million years ago.

At the heart of Rodinia was Laurentia, or the precursor to most of North America. Debate exists, however, on whether East Antarctica, Australia, Siberia, or South China fit with the western margin of Laurentia. This geologic discovery provides three lines of evidence in support of an East Antarctica – Laurentia connection.

Researchers theorize that about 600-800 million years ago, a portion of Rodinia broke away, gradually drifting southward to become eastern Antarctica and Australia. This movement just predates the Cambrian explosion, a rapid diversification of life and sudden appearance of complex organisms. Goodge explains that “there are ideas developing about these connections between the geo-tectonic world on the one hand and biology on the other.” It is possible that the shifting and colliding of continents, erosion, and influx of minerals and chemicals into the ocean may have provided nutrients to support a growing diversity of organisms.

Connecting to the National Science Education Standards

As with a discussion of Pangaea or plate tectonics in general, this article provides an opportunity to meet the Earth and Space Science standard’s various concepts. According to the National Science Education Standards, “The idea of systems provides a framework in which students can investigate the four major interacting components of the earth system – geosphere, hydrosphere, atmosphere, and the biosphere. In this holistic approach to studying the planet, physical, chemical, and biological processes act within and among the four components on a wide range of time scales to change continuously earth’s crust, oceans, atmosphere, and living organisms.” The holistic approach described in the NSES is reflected in this study’s use of geologic evidence to explain an important biological phenomenon.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

Rather than spark a new lesson, this current event provides an opportunity to revisit a familiar unit on plate tectonics, geologic time, and rocks and minerals. Most teachers include a discussion of Alfred Wegner and the evidence for his theory of plate tectonics, including similar fossilized plants and reptiles found in South America and Africa.

After students understand how Wegner used geologic and fossil evidence to reconstruct Pangaea, present the evidence from this most recent discovery. Ask them to explain how the same type of granite could be found in eastern Antarctica and the southwest United States. Once students conclude that the two continents must have been connected, re-examine a diagram of Pangaea, which shows an African-Antarctic connection, not a North America-Antarctic one. How, then, could these two places have similar rocks?

A reconstruction of the supercontinent Pangaea. Image courtesy of Kieff via Wikimedia.

Referring to geologic time may help at this point. Using a modified time scale, remind students that Pangaea existed approximately 200 million years ago, while earth is approximately 4.6 billion years old. What did earth’s surface look like before Pangaea? Lead students to the conclusion that other supercontinents, like Rodinia, existed well before Pangaea. Introduce the concept of the supercontinent cycle.

This type of discussion naturally progresses to the mechanics and processes driving the cycle: plate movement. The following resources from the Middle School Portal can help you teach about earth’s interior and plate tectonics. It may also be helpful to brush up on concepts related to geologic time, as these processes span millions of years.

Geologic Time: Eons, Eras, and Epochs

Plate Tectonics: Moving Middle School Science

Once students understand plate interactions (rifting, subduction, sea-floor spreading), take a global view. Using a world map, plot the locations of plate divergence and convergence. Challenge students to predict what the next supercontinent will look like. For example, current plate movement indicates that as the Atlantic Ocean basin grows, the Pacific Ocean basin is shrinking. In the future, western North America may be connected to Asia in the earth’s latest supercontinent. This story from NPR, Amasia: The Next Supercontinent?, tells the possible story.

Introducing Rodinia as part of a greater supercontinent cycle presents plate tectonics as a driving force in a long-term pattern of constructive and destructive forces. It provides another opportunity for students to consider the cyclic change: a fundamental principle in science.

We Want Your Feedback
We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org. This post was originally written by Jessica Fries-Gaither and published July 24, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 2/8/12 by Jessica Fries-Gaither.

Teaching about Volcanic Hazards

You’ve probably heard that Redoubt, a volcano 100 miles southwest of Anchorage, Alaska, has been erupting intermittently since March 22. I used to live in Anchorage, so I’ve been keeping up with the volcano’s activity via the Alaska Volcano Observatory web site. I’m thankful that I’m not there to deal with the major hazard – ash.

redoubt.jpg
View to the east of the summit crater of Redoubt volcano, heavily covered with deposits from recent eruptions. The near ridge, right of the notch, is the upper reach of the Crescent Glacier on the southwest flank. March 31, 2009. Photo courtesy of Game McGimsey and the Alaska Volcano Observatory/U.S. Geological Survey.

Volcanic ash consists of tiny jagged pieces of rock and glass. These hard, abrasive particles are spread by wind and impact communities in a variety of ways – including damage to planes and cars, ventilation systems of buildings, water pollution, and possible respiratory problems.

 ash-sem.jpgash-sem.jpg
Scanning Electron Microscope image of ash particles erupted by Redoubt volcano on March 22, 2009. Image courtesy of Tom Kircher and the Alaska Volcano Observatory/University of Alaska Fairbanks Geophysical Institute.

In Alaska, Redoubt’s ashfall has led to flight cancellations, school closings, disruptions to the oil industry, and even delays in seafood shipments.

 ash-on-car.jpg
Volcanic ash fall out in Nikiski, AK from Redoubt volcano. Photo courtesy of Kristi Wallace and the Alaska Volcano Observatory/U.S. Geological Survey.

Other volcanic hazards include aerosols, lahars, pyroclastic flows, lava flows, and landslides. Some of the most well-known eruptions have caused a great deal of damage – think of the mudflows after the 1991 eruption of Mount Pinatubo or the explosion and ash cloud of Mount St. Helens in 1980. Scientists are trying to better understand the inner workings of volcanoes to predict eruptions and minimize damage. During an eruption such as Redoubt’s current activity, mathematical modeling of atmospheric currents helps predict which areas will be most affected by ashfall.

While volcanoes are almost always part of a broader study of plate tectonics, we don’t always take the time to focus on the impacts of eruptions on humans. The following resources take this approach to studying volcanoes and thus align with the Science in Personal and Social Perspectives content standard of the National Science Education Standards.

Volcanoes – Local Hazard, Global Issue
http://missiongeography.org/58mod1.htm
This module allows middle school students to explore two ways that volcanoes affect Earth: by directly threatening people and environments adjacent to them and by ejecting aerosols into the atmosphere. Through three investigations, students explore issues of volcano hazards at different scales, from their local environment to the global effect of volcanic aerosols on climate and aircraft safety.

Mount Pinatubo: The Aftermath of a Volcanic Eruption
http://www.teachersdomain.org/resource/ess05.sci.ess.earthsys.lahar/
This video (3:30) shows the ash fall and mud flows triggered by the eruption of Mount Pinatubo in 1991. Questions for discussion lead students to consider the effects of volcanic eruptions on humans and how communities near volcanoes can protect themselves in the future.

Volcano Hazards Program
http://volcanoes.usgs.gov/
The USGS web site provides information about the 169 active volcanoes in the United States, teaching resources, information about volcanic ash, and volcano webcams.

Volcanoes and Climate Change
http://eob.gsfc.nasa.gov/Features/Volcano/
This article from NASA explains how volcanic eruptions impact global climate.

Seismic Signals
http://www.teachersdomain.org/resource/ess05.sci.ess.earthsys.seismic/
This interactive activity from NOVA Online illustrates some of the clues seismologists are using to better understand activity within a volcano and predict eruptions.


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We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org. Post updated 12/07/2011.

Using Real Data in Life, Earth, and Physical Sciences Classes

When students interpret data and communicate inferences, they are building skills that will help them solve problems throughout their lives. With the investigations featured in these resources, students will collect data and present and analyze their findings. These skills are an important part of the Science as Inquiry strand in the National Science Education Standards.

Monarch Watch
This network of students, teachers, and researchers is dedicated to the tagging, rearing, and study of the monarch butterfly. Each spring, the network publishes a season summary that contains tag recovery data, tips and ideas for teachers and students, observations on monarch populations, and new information on monarch biology. Other projects include life history studies, flight vector analysis, and butterfly gardening. A K-8 science curriculum titled Monarchs in the Classroom (available through the mail) offers standards-based lessons.

Boil, Boil, Toil and Trouble: The International Boiling Point Project
Which do you think has the greatest influence on the boiling point of water: room temperature, elevation, volume of water, or heating device? The answer to this question requires input from people all over the world, and this online collaboration allows your students to enter the investigation. The students will boil water, under controlled conditions, record information, and post it online. They can analyze the data sent in by others worldwide and reach their own conclusions on what makes a pot of water boil.

Musical Plates: A Study of Earthquakes and Plate Tectonics
In this series of lessons, students use real-time data to study the correlation between earthquakes and tectonic plates and to determine whether or not there is a relationship between volcanoes and plate boundaries. The science and the data analysis are demanding but still within the range of upper-level middle school students. Four activities, each designed to be used in a 45-minute class period, teach students how to access and interpret real-time earthquake and volcano data. Three enrichment lessons follow in this teacher-friendly unit.


We Want Your Feedback
We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org. Post updated 4/19/2012.

Seafloor Spreading

Seafloor spreading can be a difficult concept for middle school students to grasp. These resources should help make the concept comprehensible through the use of images and animations and by acknowledging the concept’s larger context of plate tectonics.

Harry Hess: One of the Discoverers of Seafloor Spreading
This detailed biography shows how Hess’s skills enabled him to contribute to the scientific knowledge base of seafloor spreading and how his observations, models and predictions support the theory of plate tectonics.

The Distance Between Us and Them: Seafloor Spreading in the Atlantic Ocean
In this activity, students gain an understanding of how geologists determine rates of seafloor spreading. Using a strip map of the North Atlantic seafloor, students measure distances and note the ages of the strips of basalt. They also gain experience in applying mathematical concepts such as calculation and use of velocities and conversion from one set of units to another.

Seafloor Spreading
This page, part of the NeMO project, provides a concise explanation and a graphic representation of seafloor spreading and its relationship to divergent tectonic plates. Related links at the bottom of page include a link to mid-ocean trenches.

This Dynamic Earth: The Story of Plate Tectonics
This free, online booklet, containing photos and graphic illustrations, puts the idea of seafloor spreading in the larger context of plate tectonics.

Interactive Animation of Seafloor Spreading and Magnetic Field Reversals
Earth’s magnetic field reverses itself from time to time; North becomes South and South becomes North. Rocks on the seafloor on either side of a mid-ocean spreading ridge preserve a record of the Earth’s magnetic field over time. This page also shows how distance from the ridge is related to age or time.


We Want Your Feedback
We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org. Post updated 11/08/2011.