Continental Drift and Seafloor Spreading

Flashcards about Continental Drift and Seafloor Spreading

Who proposed the past existence of Pangaea and the Theory of Continental Drift?

Alfred Wegner

What are some pieces of evidence supporting the Theory of Continental Drift?

Fossils, Rock Sequences, Animal Plant Fossils, Past tropical climates, Fit of Continents, glacial Striations, Paleomagnetism, Salt Deposits, Lime Stone Deposits, and Mountain Ranges

How do fossils support the Theory of Continental Drift?

Fossils of the same animal and plant were found on separate continents, suggesting the land masses were once connected.

How do rock sequences support the Theory of Continental Drift?

Matching rock sequences (layers) found on separate continents indicate they were once connected.

How does climate support the Theory of Continental Drift?

Evidence of past tropical climates in Antarctica, such as coal and salt deposits, suggests Antarctica was once in a warmer region.

How does the fit of continents support the Theory of Continental Drift?

The puzzle-like fit of continents, particularly between South America and Africa, provides strong evidence they were once joined.

How do glacial striations support the Theory of Continental Drift?

Glacial striations found on warm continents suggest those continents were once in a polar region.

How does paleomagnetism support the Theory of Continental Drift?

Rocks of the same age on different continents point to different magnetic poles, suggesting they were once connected.

Why was Continental Drift not readily accepted at first? (3 reasons)

Alfred Wegner was a meteorologist, not a geologist & he studied rocks and he couldn't explain how continents moved.

Who was Captain Harry Hammond Hess?

A geologist who helped develop the theory of plate tectonics and provided the mechanism for how continents could move.

What did Harry Hess contribute to Wegener's hypothesis?

He provided the mechanism of how continents could move, showing that new crust formed at Mid-Ocean Ridges and moves away over time.

What is the Theory of Seafloor Spreading?

The process of new oceanic crust forming at a mid-ocean ridge and then moving away over time, driven by magma and eventually leading to subduction.

What evidence supports Seafloor Spreading?

Glomar Challenger discoveries (thin layers at ridge, thicker away), radiometric dating (younger rock at ridge, older at trench), and magnetometer data (magnetic intensity of minerals).