Materials List: Gondwana Continents BLM, scissors, Gondwana Student Instructions BLM, Internet connection, science learning logs
Part A: Begin by presenting students with this SQPL - Student Questions for Purposeful Learning (view literacy strategy descriptions) statement: “Coal and oil have been found in frozen Antarctica.” Students should turn to a partner and think of one good question they have about the statement. As students respond, write their questions on the board. Tell students to listen carefully for the answers to their questions as you read the online article (used with permission by the Utah State Office of Education). Pause periodically and ask students to reflect on which questions have been answered. They may write answers to their own SQPL questions in their science learning logs (view literacy strategy descriptions).
Part B: Tell students that the understanding of plate tectonics began from the work of the German scientist Alfred Wegener and Alexander Du Toit, a South African geologist. In early 1915, the Alfred Wegener developed a theory that the continents once formed a giant supercontinent that Wegener called Pangaea. He speculated that Earth took this form about 245 million years ago, during the Triassic period of the Mesozoic era. (The Mesozoic is the era in which dinosaurs lived.) A few years after Wegener proposed his theory, Alexander Du Toit further theorized that Pangaea divided into two supercontinents 205 million years ago. Du Toit called the northern supercontinent Laurasia and the southern one Gondwana. The scientists used many kinds of evidence to advance their theories. They found similar fossil remains of plants and animals on different present-day continents. The scientists hypothesized that the continents were once connected. From the early idea found in this activity, with the evidence and information gathered through exploration and the use of instruments scientists have advanced the understanding of Earth processes.
Tell students that in this activity they will follow steps to model those of Wegener and Du Toit to see if fossil evidence supports the theory that one supercontinent divided into two. Students will focus on Gondwana, the supercontinent that includes continents now called South America, Antarctica, Australia, Africa, Madagascar, and India.
Pass out the Gondwana Student Instructions BLM and Gondwana Continents BLM and instruct students to complete the activity as written. Before the students cut out the continent outlines, they will label and show supporting evidence of Gondwana on each continent (see Gondwana Student Instructions BLM). As a challenge have the students rebuild Laurasia with the remaining continents (see Resources).
Host a whole-class discussion with the following questions:
- What is the difference between an observation and an inference? (Examples should relate to historical scientists and the development of plate tectonics.)
- Scientists have found Mesosaurus fossils on the east coast of the southern tip of South America and the west coast of South Africa. Give evidence to support your ideas. (Even though we know this animal could swim, the presence of Mesosaurus fossil remaining in two places supports Wegener and Du Toit’s theory.)
- Do you think that the breakup of Pangaea into Gondwana and Laurasia affected organisms originally living on Pangaea? Do you think that the breakup of Gondwana into the southern continents affected the organisms living in Gondwana? Give evidence to support your ideas. (The breakup might trigger organisms to adapt to the new climates. If they remain in the original climate, then the breakup might cause changes in the food web, which also bring about adaptations.)
- How does this reconstruction help explain the evidence of glaciers in Africa where no glaciers currently exist? (Africa was once in the upper latitudes, near the poles)
- Why do the continents not fit together exactly? What conclusion can be made about how the continents’ coastlines changed? (The true edge of a continent is around the continental slope; the junction between continental and oceanic crust usually occurs below sea level. The processes that were in effect still are working.)
- Scientists have evidence that Glossopteris was found in what is now India, Antarctica, Australia, and Madagascar. What does this tell you about Glossopteris? What can you conclude about the climate and environment of Gondwana? (It lived in cool to warm climates with a lot of moisture.)
- Based on the geologic past, we can assume that Earth is always changing. What modern-day evidence supports this idea? Guided by the current direction of plate movement, predict the position of the continents in the next 100 million years. (El Nino, global warming, and the increase in strength and number of tropical storms are some examples. The Paleomap Project, online, shows an image of Earth’s projected landscape 50 million years from present day.)
As a culmination activity, show students the animation from the Exploratorium website which shows the breakup of Gondwana with a geologic timeline.