Science 10: Lesson 3 Processes That Occur Along The Plate Boundaries Part 2

Summary

In this educational video, Marian Soriano introduces students to plate tectonics, focusing on the processes at plate boundaries. She explains convergent boundaries where plates collide, forming trenches, volcanoes, and causing earthquakes, including tsunamis like the 2011 Japan disaster. Soriano also describes divergent boundaries, where plates move apart, creating oceanic ridges and rift valleys, and the youngest rocks near these areas. Transform faults, where plates slide past each other, are highlighted for their frequent seismic activity. The lesson aims to inform and engage, with examples like Iceland and the San Andreas Fault.

Takeaways

• 🌏 Convergent plate boundaries occur when lithospheric plates move towards each other, leading to subduction and the formation of trenches, volcanic arcs, and earthquakes.
• 🌋 Oceanic-continental convergence results in trenches, volcanic arcs, and can trigger earthquakes that may cause tsunamis, as exemplified by the 2011 Japan earthquake.
• 🏞️ Oceanic-oceanic convergence leads to the formation of trenches, volcanic island arcs, and strong earthquakes that can generate tsunamis.
• 🏔️ Continental-continental convergence does not create subduction zones but instead forms mountain ranges and causes shallow earthquakes due to the collision of crustal plates.
• 🌊 Divergent plate boundaries are characterized by plates moving apart, leading to the creation of oceanic ridges and reef valleys due to magma formation from mantle convection currents.
• 🌋 The Mid-Atlantic Ridge is a mid-ocean ridge that is part of the longest mountain range in the world, formed by divergent plate movement.
• 📊 Rocks near the oceanic ridge are younger than those far from it, indicating the process of seafloor spreading and the creation of new crust.
• 🏞️ Continental divergence can lead to the formation of a continental rift valley, which may eventually evolve into a narrow sea and then a widened ocean.
• 🇮🇸 Iceland is situated above the Eurasian and North American plates that are diverging, with the Zinfandler National Park being a notable attraction.
• 🏗️ Transform fault plate boundaries occur when plates slide past each other horizontally, causing earthquakes due to the jagged edges of plates catching and sticking.
• 🌀 Transform faults, such as the San Andreas Fault, are characterized by horizontal movement without the destruction of the plate's leading edge, resulting in earthquakes rather than volcanic activity or mountain formation.

Q & A

What is a convergent plate boundary?

A convergent plate boundary is where two lithospheric plates are moving towards each other, often resulting in one plate being subducted beneath the other, leading to the formation of trenches, volcanic arcs, and earthquakes.

What happens during the convergence of oceanic and continental crustal plates?

During the convergence of oceanic and continental crustal plates, the denser oceanic plate is subducted under the continental plate, forming trenches and volcanic arcs, and causing earthquakes.

What are the consequences of the convergence of oceanic to oceanic crustal plates?

The convergence of oceanic to oceanic crustal plates leads to the formation of trenches, volcanic island arcs, and strong earthquakes that can generate tsunamis.

Why do two continental crustal plates not form volcanoes when they collide?

When two continental crustal plates collide, there is no subduction zone because neither plate is dense enough to be forced under the other, resulting in a collision zone that forms mountain ranges and shallow earthquakes instead of volcanoes.

What is a divergent plate boundary?

A divergent plate boundary occurs when lithospheric plates are moving apart from each other, allowing magma to rise from the mantle and create new crust, forming features like oceanic ridges and rift valleys.

How are oceanic ridges formed?

Oceanic ridges are formed at divergent boundaries where convection currents in the mantle cause magma to rise and create new crust as the plates move apart, leading to the development of underwater mountain ranges.

What is a reef valley and how does it form?

A reef valley is a linear shaped lowland that forms between oceanic ridges as the oceanic crust, being thinner than continental crust, stretches and creates a depression in the ocean floor.

Why are rocks near the mid-Atlantic ridge younger than those far from it?

Rocks near the mid-Atlantic ridge are younger because this is an active divergent boundary where new oceanic crust is continuously being formed by the upwelling of magma from the mantle.

How does a transform fault plate boundary differ from a divergent boundary?

A transform fault plate boundary involves plates sliding past each other horizontally without creating or destroying crust, resulting in earthquakes rather than the formation of new crust or volcanic activity seen in divergent boundaries.

What causes earthquakes at transform fault boundaries?

Earthquakes at transform fault boundaries are caused by the jagged edges of tectonic plates catching and sticking as they slide past each other, building up stress that is released when the plates suddenly slip.

Why are most transform faults located within ocean basins?

Most transform faults are located within ocean basins because this is where many of the Earth's tectonic plates meet and interact, although some, like the San Andreas Fault, do cut through continental crust.