THE CONTINENTAL DRIFT THEORY BY ALFRED WEGENER

Discusses the idea of continental drift theory

1. CONTINENTAL DRIFT THEORY Prepared By: Sandylyn P. Singson

2. LEARNING OBJECTIVES At the end of the discussion the students must be able to: explain how the continents drift; cite pieces of evidence that support continental drift; and 1 2 3 explain plate tectonics as a unifying theory.

3. THE CONTINENTAL DRIFT HYPOTHESIS 01

4. The Continental Drift Hypothesis Proposed by German meteorologist Alfred Wegener. In 1915, he wrote The Origin of Continents and Oceans that contains the continental drift hypothesis. States that the movement of plates caused and is still causing the movement of continents.

5. The Continental Drift Hypothesis Continental drift hypothesis states that all known landmasses on Earth were once joined in one supercontinent known as Pangaea (meaning “all- lands”). It is surrounded by a huge ocean known as Panthalassa. It began to break into smaller landmasses about 200 million years ago which is composed of Laurasia and Gondwanaland.

6. The Continental Drift Hypothesis The northern supercontinent was the Laurasia which is the origin of North America and Eurasia except India. The southern supercontinent was Gondwanaland was previously composed of South America, Africa, Australia, India, and Antarctica.

7. EVIDENCE SUPPORTING CONTINENTAL DRIFT THEORY!

8. EVIDENCE SUPPORTING THE CONTINENTAL DRIFT HYPOTHESIS 1. CONTINENTAL FIT The shapes of continents fit each other. Noticed that some continents remarkably fit especially Africa and South America. The shape of South America and Africa fit each other

9. EVIDENCE SUPPORTING THE CONTINENTAL DRIFT HYPOTHESIS 2. FOSSIL EVIDENCE Similar fossils found across continents. Wegener discovered similar fossil remains of organisms were found from both South America and Africa. Fossil patterns across continents

10. EVIDENCE SUPPORTING THE CONTINENTAL DRIFT HYPOTHESIS FOSSIL EVIDENCE Presence of “seed fern” fossils known as Glossopteris in Africa, Australia, India, South America, and was later on recorded in Antarctica. Glossopteris

11. EVIDENCE SUPPORTING THE CONTINENTAL DRIFT HYPOTHESIS FOSSIL EVIDENCE Mesosaurus is an aquatic fish-catching reptile found in black shales from eastern South America and southwestern Africa was dated to be about 260 million years old. Mesosaurus

12. EVIDENCE SUPPORTING THE CONTINENTAL DRIFT HYPOTHESIS FOSSIL EVIDENCE Lystrosaurus a mammal-like herbivorous land-dwelling reptile was found in Africa, India, and Antarctica. Lystrosaurus

13. EVIDENCE SUPPORTING THE CONTINENTAL DRIFT HYPOTHESIS FOSSIL EVIDENCE Cynognathus , an advanced therapsid which is mammal-like land reptile was also found in South America and Africa. Cynognathus

14. EVIDENCE SUPPORTING THE CONTINENTAL DRIFT HYPOTHESIS 3. ROCKS & MOUNTAIN Similarities in rocks and mountains across continents. Presence of 2.2-billion-year-old igneous rocks in Brazil that is similar to the rocks found in Africa. Mountain Similarities

15. EVIDENCE SUPPORTING THE CONTINENTAL DRIFT HYPOTHESIS 3. GLACIAL EVIDENCE Similarities in possible conditions . presence of a glacial period dated about 300 million years ago in South Africa, South America, Australia, and India. Paleoclimactic evidence

16. CRITICISM ON WEGENER’S CONTINENTAL DRIFT HYPOTHESIS His inability to identify a credible mechanism for how continents move. Incorrectly explained that larger and sturdier continents broke through thinner oceanic crust.