Podcast
Questions and Answers
Initially, Alfred Wegener's theory of continental drift was predominantly met with what response from the scientific community?
Initially, Alfred Wegener's theory of continental drift was predominantly met with what response from the scientific community?
- Enthusiastic endorsement and rapid expansion of his research.
- Cautious interest, pending further technological advancements.
- General skepticism and rejection due to lack of a clear mechanism. (correct)
- Immediate acceptance due to compelling fossil evidence.
The discovery of the Mid-Atlantic Ridge in 1948 was significant to the theory of continental drift primarily because it revealed:
The discovery of the Mid-Atlantic Ridge in 1948 was significant to the theory of continental drift primarily because it revealed:
- large deposits of sedimentary rock formations similar to continental shelves.
- a submerged mountain range made of unexpectedly young volcanic rock. (correct)
- evidence of deep ocean trenches indicative of crustal subduction zones.
- a chain of islands composed of ancient, eroded continental crust.
Post-World War II sonar mapping of the ocean floor played a crucial role in advancing the understanding of continental drift by:
Post-World War II sonar mapping of the ocean floor played a crucial role in advancing the understanding of continental drift by:
- mapping large-scale deposits of metallic nodules and mineral ores.
- identifying vast, uniformly flat abyssal plains across the ocean basins.
- discovering a continuous global mid-ocean ridge system resembling seams. (correct)
- locating extensive networks of underwater canyons and river systems.
The concept of 'plates' in the lithosphere revolutionized the understanding of Earth's surface by indicating that:
The concept of 'plates' in the lithosphere revolutionized the understanding of Earth's surface by indicating that:
The combined findings of mid-ocean ridges, deep ocean trenches, and lithospheric plates collectively provided the scientific community with a mechanism to explain:
The combined findings of mid-ocean ridges, deep ocean trenches, and lithospheric plates collectively provided the scientific community with a mechanism to explain:
Flashcards
Continental Drift
Continental Drift
A theory that the Earth's continents have moved over geologic time relative to each other.
Mid-Atlantic Ridge
Mid-Atlantic Ridge
A submerged mountain range, primarily made of young volcanic rock, that runs through the Atlantic Ocean.
Deep Ocean Trenches
Deep Ocean Trenches
Deep depressions in the ocean floor, often found where one plate subducts under another.
Lithosphere
Lithosphere
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Plates (Tectonic)
Plates (Tectonic)
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Study Notes
- Alfred Wegener's continental drift theory was largely dismissed until new evidence emerged after his death in 1930.
- This new evidence helped describe the mechanism for continental movement.
- The new evidence is an example of how science can change an existing theory.
New Evidence from Below
- In 1948, scientists discovered the Mid-Atlantic Ridge, a submerged mountain range of young volcanic rock.
- Post-World War II, sonar mapping revealed cracks in the Earth's crust, known as the lithosphere.
Lithosphere Discovery
- The Mid-Atlantic Ridge runs around the entire Earth through the ocean floor.
- A steep valley exists at the center of the mid-ocean ridge.
- Deep ocean trenches were also located, suggesting that the continental crust sits on top of the oceanic crust.
- The Earth's crust is divided into plates made of lithosphere that fit together.
Investigation into Clues from the Ocean
- Magnetic reversals were found as magma cooled to form new lithosphere.
- Iron oxides in the rock align with the Earth's magnetic field, revealing shifts in magnetic poles.
- Scientists discovered a pattern of magnetic orientation stripes on either side of the mid-ocean ridges.
- The only way that these identical patterns could exist would be if they formed at the same time and moved in opposite directions.
- This led to the idea of seafloor spreading
Seafloor Spreading
- The center of the mid-ocean ridge valley is very hot, with magma leaking out and pushing aside existing crust.
- Seafloor spreading provided the first physical evidence of lithosphere movement.
- Seafloor spreading splits Iceland, creating new land through volcanic activity.
- Volcanic rocks near the mid-ocean ridge are younger than rocks farther away.
- Earthquake data coincided with cracks or faults in the lithosphere.
The Mystery Solved
- Continents are part of larger plates, not moving through the ocean crust.
- The plates move, carrying the continents.
- This new data led to the theory of plate tectonics.
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Description
Alfred Wegener's continental drift theory was dismissed until new evidence emerged after his death. Evidence such as the discovery of the Mid-Atlantic Ridge and magnetic reversals helped support the theory continental movement. The Earth's crust is divided into plates made of lithosphere that fit together.
