Practice QuestionsUse the following information for both practice questions.
Scientists believe that Earth's continents were once joined together into a single landmass called Pangaea. This supercontinent began to break up 175 million years ago and slowly drifted apart in a process known as continental drift to form the separate continents we see today. This diagram shows what Pangaea is believed to have looked like and how the continents drifted apart to appear as they do today.
- What was the main cause of continental drift?
A. Convection currents within the Earth's fluid mantle caused the tectonic plates floating on the mantle to move relative to each other and separate B. Thermal expansion of the rock due to human-caused global warming C. The meteorite that killed off the dinosaurs smashed into Pangaea 65 million years ago, causing it to split and drift apart D. Tremors left over from the Big Bang that created the universe
- Which of the following statements does NOT support the Pangaea theory?
A. Identical deposits of minerals have been found at corresponding locations along both the African and South American coasts. B. The shape of the west coast of Africa seems to fit perfectly with the shape of the east coast of South America. C. Paleontologists have discovered matching fossils from identical species of land animals at corresponding locations along both the African and South American coasts. D. The Big Bang theory states that all matter in the universe expanded outward from the same point in space.
Answers and Explanations
- The correct answer is A.
Continental drift is caused by convection currents within the Earth's mantle, which made the tectonic plates (that float on top of the mantle) separate. Hence, Choice (A) is right.
Although human-caused global warming is a serious problem, it has only happened quite recently (within the last two centuries), whereas continental drift began 175 million years ago, making Choice (B) incorrect. The meteorite that may have killed off the dinosaurs smashed into Earth 65 million years ago, but Pangaea began drifting apart 175 million years ago, so Choice (C) is wrong. Similarly, the Big Bang happened 15 billon years ago, so Choice (D) is incorrect.
- The correct answer is D.
The Big Bang theory refers to the beginning of the universe, not the breakup of Pangaea, so Choice (D) is your answer. All the other choices add support to the single supercontinent theory.