Plate Tectonics — Set 1

Correct Answer: D. Transform boundary

A transform boundary occurs when two tectonic plates slide horizontally past one another. This movement typically causes significant earthquake activity without creating or destroying crust. The San Andreas Fault is a famous example of this boundary type.

Correct Answer: C. Harry Hess

Harry Hess proposed the theory of sea floor spreading in the early 1960s. He suggested that new oceanic crust forms at mid-ocean ridges and spreads outward. This discovery provided a crucial mechanism for the theory of plate tectonics.

Correct Answer: C. Convection currents in the mantle

Convection currents in the Earth's mantle are the primary driver of plate movement. Heat from the core causes magma to rise, cool, and sink in a continuous cycle. This process exerts a dragging force on the lithospheric plates above.

Correct Answer: B. The Himalayas

The Himalayas were formed due to the convergent collision between the Indian and Eurasian plates. This is an example of a continent-continent convergence where the crust buckles upward. These mountains continue to rise as the plates move together.

Correct Answer: D. Pacific Ocean

The Ring of Fire is a large horseshoe-shaped area in the Pacific Ocean basin. it is associated with a nearly continuous series of oceanic trenches and volcanic arcs. Most of the world's active volcanoes are located in this region.

Correct Answer: A. Lithosphere

The lithosphere is the rigid outer layer of the Earth that is broken into tectonic plates. it includes the crust and the uppermost part of the mantle. These plates float and move on top of the semi-fluid asthenosphere.

Correct Answer: C. One plate sinks beneath another

At a subduction zone, a denser tectonic plate sinks into the mantle beneath a less dense plate. This process usually occurs where oceanic crust meets continental crust. It leads to the melting of rock and the formation of volcanic arcs.

Correct Answer: C. Divergent boundary

The Mid-Atlantic Ridge is a divergent boundary where plates are moving away from each other. As the plates separate, magma rises to fill the gap, creating new oceanic crust. This ridge is the longest mountain range in the world.

Correct Answer: B. Pangea

Pangea was a massive supercontinent that incorporated almost all the Earth's landmasses. It began to break apart about 200 million years ago into the current continents. Alfred Wegener used this concept to support his theory of continental drift.

Correct Answer: B. Rift valley

A rift valley is formed on land when continental crust begins to pull apart at a divergent boundary. The East African Rift is a modern-day example of this geological process. Eventually, these rifts can widen to form new ocean basins.