5. Continental Drift Theory, Convection Current Theory, Sea Floor Spreading Theory Flashcards
Who proposed the Continental Drift Theory and in what year was it first presented?
The Continental Drift Theory was proposed by German meteorologist Alfred Wegener in 1912 AD and was first presented in 1920-21.
Example sentence: Alfred Wegener was a pioneer in the field of geology.
What evidence did Alfred Wegener discover while studying glaciers in Europe that contributed to his Continental Drift Theory?
Wegener discovered coal deposits while studying glaciers. Coal forms from dead plant matter in swamp environments, which are not characteristic of glacial environments, suggesting significant changes in the Earth’s surface over time.
Additional information: Coal deposits were a key piece of evidence supporting Wegener’s theory.
What were Wegener’s initial hypotheses to explain his findings of coal in glacial regions?
Wegener hypothesized that either (1) the climate had changed significantly over time, or (2) the continents had drifted to different locations.
Additional information: These hypotheses laid the foundation for Wegener’s Continental Drift Theory.
Which of his initial hypotheses did Wegener eventually reject, and which did he support?
Wegener rejected the hypothesis of significant climate change over time and supported the hypothesis that continents have drifted to different locations.
Example sentence: Wegener’s rejection of the climate change hypothesis was a pivotal moment in the development of his theory.
What was the name of the supercontinent during the Permian Age, and what was the mega-ocean surrounding it called?
During the Permian Age, the supercontinent was called Pangea, and the surrounding mega-ocean was called Panthalassa, known today as the Pacific Ocean.
Additional information: Pangea was a massive landmass that included most of the Earth’s continents.
How did Pangea split during the Triassic Period, and what new seas formed as a result?
During the Triassic Period, Pangea split into two large continental masses: Gondwanaland and Laurasia. The rift between these continents filled with water, forming the Tethys Sea, known today as the Mediterranean Sea.
Additional information: The splitting of Pangea had significant geological consequences.
Which continents were part of Gondwanaland, and how did they move during the Jurassic Age?
Gondwanaland included the continents of South America, Africa, India, Australia, Antarctica, and Madagascar. During the Jurassic Age, South America and Africa began moving westward, while other parts also started to shift.
Additional information: The movement of Gondwanaland had a lasting impact on the Earth’s geography.
What continents were part of Laurasia, and how did they move?
Laurasia consisted of North America, Greenland, and Eurasia. These continents also began to drift apart during the Jurassic Age.
Additional information: Laurasia’s separation marked a significant event in the history of continental drift.
Describe the movement of the continents from the Cretaceous Period to the present day.
From the Cretaceous Period to the present day: North America drifted westward from Laurasia. South America drifted westward away from Gondwana. Africa moved toward the equator. India moved north-eastward. Australia moved eastward. Antarctica remained relatively stationary.
Additional information: The movement of continents continues to shape the Earth’s surface today.
What were the forces that Wegener believed caused the continents to drift?
Wegener believed the forces causing continental drift included: SIAL (continental crust) floating on SIMA (oceanic crust) without friction. The westward movement due to tidal forces exerted by the moon and sun. Equatorward movement driven by a combination of centrifugal (pole-fleeing) force, buoyancy, and gravitational forces.
Additional information: Wegener’s concept of continental drift was based on a combination of geological and astronomical forces.
What is one major criticism regarding the forces proposed by Wegener to explain continental drift?
One major criticism is that tidal forces are not strong enough to move the continents and his explanations do not satisfy present-day characteristics of forces.
Additional information: Critics have questioned the feasibility of Wegener’s proposed mechanisms for continental drift.
How did Wegener explain the formation of the Rocky Mountains, and what was the criticism of this explanation?
Wegener explained that SIAL faced obstruction from SIMA while floating over it, causing SIAL to accumulate and form the Rocky Mountains. The criticism was that this contradicted his own concept that SIAL moves on SIMA without any friction.
Additional information: The formation of mountain ranges played a key role in Wegener’s theory of continental drift.
Why did Wegener’s theory fail concerning the pre-Carboniferous era?
Wegener’s theory failed to explain the scenario of continents before the Carboniferous era.
Additional information: The limitations of Wegener’s theory were exposed when trying to account for geological events before a certain period.
What was Wegener’s explanation for the formation of islands, and why was it criticized?
Wegener explained that islands formed because some parts of continents moved slower than others, leaving parts behind that became islands. This explanation was criticized for being unsatisfactory.
Additional information: The formation of islands presented a challenge to Wegener’s theory of continental drift.
What is the ‘Jig-Saw-Fit’ evidence that supports Wegener’s Continental Drift Theory?
The ‘Jig-Saw-Fit’ evidence refers to the remarkable match of the coastlines of South America and Africa, where the bulge of Brazil fits into the coast of Ghana, and the Scandinavian parts of Europe fit into North America.
Additional information: The ‘Jig-Saw-Fit’ evidence provided compelling visual proof of continental drift.
