The correct answer is:
D. motion of the tectonic plates
This process is responsible for the movement of large landmasses over time, leading to continental drift.
Continental Change
Earth has not always looked like it does now. Two hundred and fifty million years ago, the continents were one big landmass known as Pangea (Pangaea). The Atlantic and Indian Oceans did not exist. The landmass was encircled by one large ocean. Over time, the landmass began to break apart. The large pieces of broken land drifted away from one another to create the continents we know today. The idea of this movement of land is known as continental drift. The timeline shows the movement of the land.
The timeline shows the continental drift on Earth across the Paleozoic, Mesozoic and Cenozoic periods. About 245 million years ago, near the end of the Paleozoic period, Pangea was a single landmass. About 135 million years ago, during the Mesozoic period, Pangea split into Laurasia and Gondwana. About 65 million years ago, at the beginning of the Cenozoic period, the landmasses further split into 7 continents. Today, the continents have moved further apart.
Studying fossils has helped scientists arrive at the theory of continental drift. Without oceans between them, landmasses were once connected to each other and organisms could easily travel from continent to continent. Similar fossils were found on continents that are now separated by huge distances. Four main fossil types—Mesosaurus, Cynognathus, Lystrosaurus, and Glossopteris—provide evidence for continental movement over time. The Mesosaurus was a freshwater reptile that lived before dinosaurs. Cynognathus and Lystrosaurus were land reptiles. They lived on land and could not swim. Glossopteris plants had large, bulky seeds. The diagram shows the fossil distribution of how the organisms could have existed when landmasses were closer together.
The diagram shows that fossils of the land reptile Cynognathus were found across South America and Africa. Fossils of the freshwater reptile Mesosaurus were found across South America and Africa. Fossils of the land reptile Lystrosaurus were found across Africa, India and Antarctica. Fossils of the fern plant Glossopteris were found across South America, Africa, India, Antarctica, and Australia.
Multiple Choice Question
What process could be responsible for the movement of large landmasses over time?
A.
erosion of the land
B.
flooding of the oceans
C.
effects of global warming
D.
motion of the tectonic plates
1 answer