1-16-18 Continental Drift

Do Now: In your Science Notebook, copy the statements and state whether your agree or disagree with the following statements. 1. India has always been north of the equator. 2. All the continents once formed one supercontinent.

The Continental Drift Hypothesis Lesson Objectives: Students will be able to describe the pieces of evidence that support the continental drift hypothesis. Standards: SC.7.E.6.2, SC.7.E.6.4, SC.7.1.7, SC.7.N.2.1

Essential Questions What evidence supports continental drift? Why did scientists question the continental drift hypothesis?

Vocabulary Pangaea Continental drift

Pangaea Nearly 100 years ago, Alfred Wegener proposed that all the continents were once part of a supercontinent called Pangaea: name given to a supercontinent that began to break apart approximately 200 million years ago. Nombre dado a un supercontinente que empezo a separarse hace aproximadamente 200 millones de anos.

Pangaea Over time, Pangaea began breaking apart and the continents slowly moved to their present position.

Pangaea Nearly 100 years ago, Alfred Wegener (VAY guh nuhr)Wegener proposed the hypothesis of continental drift, which suggested that continents are in constant motion on the surface of Earth. Deriva continental: hipotesis de Wegener que sugirio que los continentes estan en constante movimiento en la superficie de la Tierra.

Pangaea Wegener observed the similarities of continental coastlines now separated by oceans and how they could fit together like pieces of a puzzle. The eastern coast of South America mirrors the shape of the west coast of Africa

Evidence That Continents Move The most obvious evidence for continental drift is that the continents appear to fit together like pieces of a puzzle. But scientists were skeptical, and Wegener needed additional evidence to help support his hypothesis. Evidence to support Wegener’s hypothesis is found in climate clues; fossil clues; rock clues.

Evidence That Continents Move When Wegener pieced Pangaea together, he proposed that the continents were located closer to the South Pole 250 million years ago. Wegener suggested that a large sheet of ice covered the continents.

Evidence That Continents Move Wegener studied the sediments left behind and the glacial grooves that formed when the ice sheets melted and Pangaea spread apart. The presence of an ice sheet covering Pangea could explain glacial features found on some continents today. This provided climate evidence for continental drift.

Evidence That Continents Move Animals and plants that live on separate continents can be unique to that continent alone. Lions are only found on Africa but not in South America; kangaroos are only found on Australia. Because oceans separate continents, these animals cannot travel from one continent to another by natural means.

Evidence That Continents Move Fossils of similar organisms have been found on several continents separated by oceans. Fossils of a plant called Glossopteris (glahs AHP tur us) have been found on continents that are now separated by oceans. Fossils provide evidence for continental drift Also, evidence suggests that Glossopteris grew in a swampy environment. Therefore, this region had a warm and wet climate.

Evidence That Continents Move Wegener observed that mountain ranges and rock formations on different continents had common origins, providing rock evidence for continental drift. The Caledonia mountain range in northern Europe and the Appalachian Mountains in eastern North America are similar in age, structure, and rock type.

Volcanic rock (cratons) that is identical in chemistry and age has been found on both the western coast of Africa and the eastern coast of South America. Similarities in rocks on different continents provide evidence for continental drift.

Think about the question independently for 15 seconds, then turn & talk with your shoulder partner to share and discuss your answer. How were similar rock types used to support the continental drift hypothesis? Similar rock types in mountains such as the Appalachian Mountains and the Caledonian Mountains suggest that North America and northern Europe were at one time connected. Likewise, similar volcanic rocks in Africa and South America suggest that these two continents were also joined.

What was missing? Wegener’s ideas were not widely accepted until nearly four decades later. Scientists questioned continental drift because it was a slow process and Wegener could not measure how fast continents moved or how they moved. Scientists could not understand how continents could push their way through the solid rock of the mantle and the seafloor. The main objection was that Wegener could not explain what forces caused the continents to move. The evidence necessary to prove continental drift was not discovered until long after Wegener’s death.

All continents were once part of a supercontinent called Pangaea.

Alfred Wegener proposed that continents move around on Earth’s surface.

Alfred Wegener proposed that continents move around on Earth’s surface.

What term did Wegener use to describe the constant motion of continents on the surface of Earth? A. Pangaea B. continental drag C. continental movement D. continental drift

Lesson 1 – LR2 In which of these did Wegener observe similarities that suggested continents might fit together like the pieces of a puzzle? A. fossils B. ice sheets C. plates D. continental coastlines

Lesson 1 – LR3 Wegener proposed that 250 million years ago, South America, Africa, India, and Australia were located closer to what? A. equator B. South Pole C. North Pole D. Pacific ocean

Homework: Turn in Science Fair Data Table, Graph, Results, & Conclusions