What are the different theories of plate tectonics?
Three-dimensional diagram showing crustal generation and destruction according to the theory of plate tectonics; included are the three kinds of plate boundaries—divergent, convergent (or collision), and strike-slip (or transform).
What are the disadvantages of divergent plate boundaries?
Effects that are found at a divergent boundary between oceanic plates include: a submarine mountain range such as the Mid-Atlantic Ridge; volcanic activity in the form of fissure eruptions; shallow earthquake activity; creation of new seafloor and a widening ocean basin.
What happens when two continental plates of different densities collide?
When plates of differing densities collide, the plate that is more dense goes under the less dense plate. Trenches and volcanic mountains form.
What is the theory of plate tectonics Class 9?
Plate tectonics is the theory that Earth’s outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core. The plates act like a hard and rigid shell compared to Earth’s mantle.
What is the best piece of evidence for plate tectonics?
Evidence from fossils, glaciers, and complementary coastlines helps reveal how the plates once fit together. Fossils tell us when and where plants and animals once existed. Some life “rode” on diverging plates, became isolated, and evolved into new species.
What major plate is the largest?
Pacific Plate
Where does the most violent type of earthquake happen?
The world’s greatest earthquake belt, the circum-Pacific seismic belt, is found along the rim of the Pacific Ocean, where about 81 percent of our planet’s largest earthquakes occur. It has earned the nickname “Ring of Fire”.
What is the evidence of Pangea?
The rock formations of eastern North America, Western Europe, and northwestern Africa were later found to have a common origin, and they overlapped in time with the presence of Gondwanaland. Together, these discoveries supported the existence of Pangea.
Why was Wegener’s theory not accepted?
The main reason that Wegener’s hypothesis was not accepted was because he suggested no mechanism for moving the continents. He thought the force of Earth’s spin was sufficient to cause continents to move, but geologists knew that rocks are too strong for this to be true.
What was Wegener’s hypothesis called?
Continental drift was a theory that explained how continents shift position on Earth’s surface. Set forth in 1912 by Alfred Wegener, a geophysicist and meteorologist, continental drift also explained why look-alike animal and plant fossils, and similar rock formations, are found on different continents.
What is the difference between Pangea and continental drift?
Continental drift describes one of the earliest ways geologists thought continents moved over time. He called this movement continental drift. Pangaea. Wegener was convinced that all of Earth’s continents were once part of an enormous, single landmass called Pangaea.