Plate Tectonics Practice Questions

Correct answer: Alfred Wegener

Alfred Wegener proposed the Continental Drift theory in 1912, suggesting that all continents were once part of a single landmass called Pangea. Although he lacked a mechanism for movement at the time, his work laid the foundation for plate tectonics.

Correct answer: Lithosphere

The lithosphere is the rigid outer shell of the Earth, consisting of the crust and the uppermost part of the mantle. It is divided into several large and small tectonic plates that float on the more fluid asthenosphere.

Correct answer: Divergent Boundary

At a divergent boundary, plates pull apart, allowing magma to rise from the mantle to create new crust. The Mid-Atlantic Ridge is a classic example of this process occurring on the ocean floor.

Correct answer: Transform

The San Andreas Fault is a transform boundary where the Pacific Plate and the North American Plate slide horizontally past each other. These boundaries are known for frequent earthquake activity but do not typically produce volcanoes.

Correct answer: Subduction

Subduction occurs at convergent boundaries where a denser oceanic plate is pushed under a lighter continental or oceanic plate. This process creates deep-sea trenches and volcanic arcs.

Correct answer: Continental-Continental

The Himalayas were formed by the collision of the Indian Plate and the Eurasian Plate. Since both plates are composed of buoyant continental crust, neither subducts easily, causing the crust to buckle and fold upward into massive mountains.

Correct answer: Mantle convection

Convection currents in the mantle, driven by heat from the Earth's core, act as a conveyor belt that moves the overlying lithospheric plates. Magma rises, cools, and sinks in a continuous cycle.

Correct answer: Pangea

Pangea, meaning 'All Earth', was the supercontinent that incorporated almost all the landmasses on Earth. It eventually broke apart into Gondwana and Laurasia before reaching the current continental configuration.

Correct answer: Along mid-ocean ridges

New oceanic crust is constantly being created at mid-ocean ridges through seafloor spreading. As magma rises and solidifies at the ridge, older crust is pushed further away toward the continental margins.

Correct answer: Subduction of an oceanic plate

The Mariana Trench is a subduction zone where the Pacific Plate is being subducted beneath the smaller Mariana Plate. It reaches a depth of approximately 11,034 meters in the Challenger Deep.

Correct answer: New crust is created

Constructive boundaries are another name for divergent boundaries. They are 'constructive' because the volcanic activity associated with plates pulling apart adds new material to the Earth's surface.

Correct answer: Pacific Plate

The Pacific Plate is the largest tectonic plate, covering much of the Pacific Ocean basin. Most of its boundaries are active subduction zones or transform faults, contributing to the 'Ring of Fire'.

Correct answer: An area of volcanic activity not located at a plate boundary

A hotspot is a plume of hot magma rising from deep within the mantle that creates volcanic activity on the surface. The Hawaiian Islands were formed as the Pacific Plate moved over a stationary hotspot.

Correct answer: A crustal extension zone

The Great Rift Valley is a divergent boundary developing within the African continent. If the rifting continues, the region will eventually split, and a new ocean basin will form between the two landmasses.

Correct answer: All of the above

Wegener used multiple lines of evidence, including the fit of continental coastlines, identical fossils like Mesosaurus found in both Africa and South America, and matching mountain ranges to support his theory.

Correct answer: Strike-slip fault

Transform boundaries feature strike-slip faults where the motion is primarily horizontal. These faults build up significant stress that is released as energy during earthquakes.

Correct answer: Pacific Ocean

The Ring of Fire is a path along the Pacific Ocean characterized by active volcanoes and frequent earthquakes. It is caused by the subduction of various oceanic plates beneath the surrounding continental plates.

Correct answer: The study of magnetic reversals recorded in rocks

Paleomagnetism shows that the Earth's magnetic field has reversed many times. Symmetrical patterns of magnetic 'stripes' on either side of mid-ocean ridges proved that the seafloor was spreading and plates were moving.

Correct answer: Juan de Fuca Plate

The Juan de Fuca Plate is a small tectonic plate located off the coast of the Pacific Northwest. It is currently subducting under the North American Plate, creating the Cascade Range volcanoes.

Correct answer: Oceanic-Continental convergence

The Andes were formed by the subduction of the oceanic Nazca Plate beneath the continental South American Plate. This convergence led to intense volcanic activity and the uplift of the mountain range.