GEOLOGY

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EARTH SCIENCE

TECTONICS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
One of the key pieces of evidence that supports the theory of plate tectonics is the puzzle fit of the continents. The theory was weakened by areas which lacked an exact fit. Later, scientists realized that the continental shelf should be included in the theory. Which statement explains why the continental shelf should be included?
A
Coastlines of continents have not changed over time.
B
Coastlines have been eroded over time, but the continental shelf is less affected by erosion and thus allows a better fit.
C
Coastlines changed as the continents broke apart and the continental shelf remained unchanged.
D
The continental shelf has grown over time and fills in the gaps, allowing for a better puzzle fit.
Explanation: 

Detailed explanation-1: -Finding identical or similar fossils in areas separated by vast distances were some of the first clues that scientists used to reconstruct past plate movement. This distribution of fossils led to theories that the southern continents were once joined in a supercontinent called Gondwana.

Detailed explanation-2: -Plate tectonics is considered a “unifying theory” in the field of geology because it synthesizes the work and theories of most other areas of geology (Oreskes and LeGrand 2003). The generation of mountains, deep-sea trenches, volcanic chains, island arcs, and rift valleys can be explained by plate motions.

Detailed explanation-3: -Magma generation, igneous intrusions, metamorphism, volcanic action, earthquakes, faulting, and folding are usually the result of plate tectonic activity.

Detailed explanation-4: -The system of ideas behind plate tectonics theory suggests that Earth’s outer shell (lithosphere) is divided into several plates that glide over the Earth’s rocky inner layer above the soft core (mantle). The plates act like a hard and rigid shell compared to Earth’s mantle.

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