Summary

This video explains the order and formation of all the supercontinents. It illustrates how plate tectonics work and how they come into play with the creation of the different supercontinents. The video outlines the major aspects of each supercontinent and what happened on Earth before, during, and after each assembly of the continents.

 

Why watch this video?

• Have you ever wondered how many supercontinents have existed?
• Would you like to know how plate tectonics work?
• Have you ever been confused by why our continents are placed as they are, how they got to be that way, and how they will look in one million years?

 

Key Terms

• Plate Tectonics: A scientific theory analyzing the movement of small and large plates of Earth’s lithosphere above the Earth’s mantle. These plates could be of two different types of crust: oceanic and continental.
• Supercontinent: The accumulation of almost all of Earth’s land masses, forming one massive landmass.
• Subduction Zone: An area where one plate is pushed into the Earth’s mantle, resulting from a collision between two plates.

 

Loose Ends

1. What is a snowball earth?

A scientific theory that explains the entire Earth was one big glacier. Scientists predict that snowball Earth has happened more than once and that each time was because of rapid climate changes. These climate changes would use up all the carbon dioxide present in the atmosphere, causing the temperatures to decrease rapidly and therefore, freezing the planet.  

2.  What are the Great Oxidation Events? When did these events occur?

The first event occurred after the formation of Kenorland where Earth was first exposed to tons of free oxygen in the atmosphere. Cyanobacteria began to form oxygen through photosynthesis, releasing it into the atmosphere. The massive increase in free oxygen in the atmosphere caused panic for the anaerobic organisms, killing off many of them as the amount of free oxygen in the atmosphere grew. The second event occurred after the breaking of supercontinent Rodinia. This event produced many complex forms of life on Earth.

3.   What is the Ring of Subduction?

Near the end of the video, the author speaks of the orthoversion theory. This theory suggests that the plates move along the subduction zone of the previous continent until they are 90 latitudinal degrees from where the previous continent was located. The ring of subduction refers to the outline of the previous continent where the plates had collided causing subduction. These subduction zones would cause mountain type terrain to form, leading the plates to form the new supercontinent.

 

Self-Test Questions

Question 1: In what order did the 6 supercontinents form?

a) Ur, Kenorland, Rodinia, Pannotia, Nuna (or Colombia), Pangaea

b) Ur, Kenorland, Nuna (or Colombia), Rodinia, Pannotia, Pangaea

c) Ur, Kenorland, Rodinia, Nuna (or Colombia), Pangaea, Pannotia

d) Ur, Kenorland, Nuna (or Colombia), Rodinia, Pangaea, Pannotia

Answer 1: The Correct Answer is B: Ur, Kenorland, Nuna (or Colombia), Rodinia, Pannotia, Pangaea

Question 2: In regards to plate tectonics, which of the following is correct?

a) Oceanic crust is less dense and thicker than continental crust

b) Oceanic crust is more dense and thicker than continental crust

c) Continental crust is less dense and thicker than oceanic crust

d) Continental crust is more dense and thicker than oceanic crust

Answer 2: Answer C is the correct answer. Continental crust is thicker and less dense than oceanic crust.  When the two types of crust collide, the oceanic crust is pushed beneath the continental crust into the Earth’s mantle.

Question 3: What were the two oldest theories on how supercontinents formed? What did they describe?

a) Interversion and Externalversion. After a supercontinent drifts apart, the continents have to travel all the way around the world to collide into each other again. After a supercontinent drifts apart, the continents stop moving and then reverse their movement to come back together.

b) Orthoversion and Extroversion. Plates follow the ring of subduction around the previous supercontinent until they meet up and collide. After a supercontinent drifts apart, the continents have to travel all the way around the world to collide into each other again.

c) Introversion and Orthoversion. After a supercontinent drifts apart, the continents stop moving and then reverse their movement to come back together. Plates follow the ring of subduction around the previous supercontinent until they meet up and collide.

d) Introversion and Extroversion. After a supercontinent drifts apart, the continents stop moving and then reverse their movement to come back together. After a supercontinent drifts apart, the continents have to travel all the way around the world to collide into each other again.

Answer 3: The correct answer is D. Introversion and Extroversion were the two oldest theories explaining how supercontinents formed. Before the newest theory in 2012, orthoversion, scientists believed that both introversion and extroversion were correct but later realized that the plates of the Earth’s mantle followed the edge of the subduction ring from the previous supercontinent until they were placed 90 latitudinal degrees from the said previous continent. The next predicted supercontinent suggests the closing of the Arctic ocean.

Question 4: What is the most crucial material of the Earth that helps us explain how and when supercontinents form? Choose the best answer.

a) Tectonic Plates

b) Oceanic Crust

c) The Asthenosphere

d) Continental Crust

Answer 4: The correct answer is B: Oceanic Crust. This is the most important material on the Earth that helps us determine how and when continents form because as the oceans move with their plates, they deposit particles into the mantle that align with the magnetic field. When the mantle cools down, we are able to see in the rock record which magnetic field that specific oceanic plate was a part of, and how long ago it was a part of that magnetic field. Tectonic plates also have a role in forming supercontinents, but the question is to test your knowledge on the video, which stated that the oceanic crust was the mostimportant material.

Question 5: Select the correct statement regarding continental and oceanic crust:

a) Oceanic crust is older than continental crust

b) Continental crust is older than oceanic crust

c) Both oceanic crust and continental crust are the same age

d) There is no way in testing the ages of oceanic and continental crust

Answer 5: Answer B if the correct answer: Continental crust is older than oceanic crust. The reason for this is because oceanic crust is alwayssubducted under continental crust when these two plates come into contact, as oceanic crust is denser. When the oceanic crust is subducted, it is pushed down and descends into the mantle due to gravity. The continental crust remains above the mantle and therefore, is older than the oceanic crust. There are pieces of the continental crust that are 4 billion years old.