Introduction To Plate Tectonics Quiz

Alfred Wegener is the correct answer because he was the first scientist to propose the theory of continental drift in 1912. He suggested that the continents were once joined together in a single supercontinent called Pangea, and over time, they drifted apart to their current positions. Wegener supported his theory with evidence from the fit of the continents, similarities in rock formations and fossils, and the distribution of climatic zones. Despite initial skepticism, his ideas laid the foundation for the modern theory of plate tectonics.

When plates move apart, it is called divergent. This occurs at divergent boundaries where two plates are moving away from each other. As the plates separate, molten material from the mantle rises to fill the gap, creating new crust. This process is responsible for the formation of mid-ocean ridges and rift valleys on land. Divergent boundaries are also associated with volcanic activity and earthquakes.

When plates slide past each other, it is known as a transform boundary. This type of plate boundary is characterized by horizontal movement, where two plates move in opposite directions. Transform boundaries are often associated with earthquakes, as the sliding of plates can cause significant friction and stress along the boundary. These boundaries can be found in locations such as the San Andreas Fault in California.

When plates move towards each other, it is called convergent. This is because convergent boundaries occur when two tectonic plates collide or come together. This movement can result in the formation of mountains, volcanoes, and earthquakes. Convergent boundaries can involve oceanic-oceanic, oceanic-continental, or continental-continental plate collisions, leading to mountain formation (continental-continental), subduction (oceanic-continental), or volcanic arcs (oceanic-oceanic).

In convection currents, denser material sinks because it is heavier and has a higher mass per unit volume. This causes it to displace the less dense material, which in turn rises. This process creates a continuous circulation of fluids, such as air or water, resulting in convection currents. Therefore, the statement that denser material sinks and less dense material rises in convection currents is true.

Seafloor spreading is the correct answer because it refers to the process in which new crust is formed at the mid-ocean ridges and then spreads outwards, creating new oceanic lithosphere. This occurs due to the upwelling of magma from the mantle, which solidifies and forms new crust. As the new crust is added, the older crust is pushed away from the ridge, leading to the continuous expansion of the ocean floor.

Subduction is the correct answer because it refers to the process where oceanic crust, usually denser than continental crust, is forced beneath another plate at a convergent boundary, forming a trench. This process is responsible for the formation of volcanic arcs and the recycling of old oceanic crust back into the mantle. The other options are incorrect as they do not accurately describe subduction.

The Earth's lithosphere, which includes the crust and uppermost mantle, is divided into several separate sections known as plates. These plates are constantly moving and interacting with each other, resulting in various geological phenomena such as earthquakes, volcanic activity, and the formation of mountain ranges. This division into plates helps explain the distribution of continents and oceans on Earth's surface and provides a framework for understanding the dynamic nature of our planet's geology.

Convection currents are responsible for driving plate movement. These currents occur in the Earth's mantle, where heat from the core causes the material to rise and cool material to sink. This creates a circular motion, known as convection, that drives the movement of the tectonic plates. As the material rises, it pushes the plates apart at divergent boundaries, while at convergent boundaries, the sinking material pulls the plates together. Therefore, convection currents play a crucial role in shaping the Earth's surface by driving plate tectonics.

When oceanic crust and continental crust converge, the denser oceanic crust would subduct (sink) beneath the less dense continental crust. This process is known as subduction. As the oceanic crust sinks into the mantle, it can create a deep ocean trench. The subduction of the oceanic crust beneath the continental crust can also lead to the formation of mountains through the collision and compression of the crustal material. Therefore, the correct answer is that the oceanic crust would subduct beneath the continental crust.