Video Lesson

Lesson Objectives

By the end of this lesson, you will be able to:

• Explain the formation of continents
• Define the Big Bang Theory
• Discuss the Continental Drift Theory

Brainstorming Question

Do you know how the Earth was formed or created? What was the Big Bang?

Dear Online Learner! The Earth, together with other planets and their moons, form the planetary system. The Sun and the planets together again form the Solar system. The formation of the Earth is similar to the creation of other companion planets of the Solar System.

Figure 1.1 The Solar System (Sun & Planets) [Wicander & Monroe, 2010]

There are different theories proposed about the formation of the Universe and Earth. The “Big Bang” is most widely accepted. According to this theory, the Universe originated sometime 10-20 billion years ago by an abrupt cosmic explosion. This space explosion followed by numerous space objects like the Sun, planets, stars, meteors, asteroids, and comets through material collision, cooling, and gravitational attraction. Our Earth was thus created from the mixture of gas and dust particles moving in space around the Sun about 4.5 billion years ago.

The first cosmic rocks solidified and created the first Earth at about 4600 to 3900 Ma and the initial land masses gathered to form the early continent called ‘Rodinia’

Figure 1.2 Neoproterozoic Supercontinent; Rodinia at about 750 Ma
(Wicander & Monroe, 2010)

During the late Cambrian period (514 Ma) the Gondwana Supercontinent evolved around the South Pole. Next to this four major continents (Gondwana, Baltica, Siberia & Laurasia) came into being during 458 Ma (in the mid-Ordovician Period). Then the Laurasia continent collided with the Baltica and closed the Iapetus Sea during the mid-Silurian (425 Ma).

The continual collision then produced the pre-Pangaea continent during the early Devonian period (390 Ma). At about 306 Ma (in the late Carboniferous period) the North American continent started to develop. By then, the Supercontinent (Pangaea) had come into being at about 255 -210 Ma. From 210 -180 Ma (in the Triassic period) this Supercontinent started to break apart.  During the late Cretaceous, the breaking-apart of Pangaea widened and bigger water masses (Oceans) created along the continental cracks. The Earth’s continents have then retained their present position during the Quaternary.

Figure 1.3 Continents at different Geological times (Gabler et al., 2007)
Tip: An additional information is available online for you at:
https://www.youtube.com/watch?v=6-vHe4599NE

At about 160 Ma, Pangaea divided into two bigger landmasses called Gondwanaland and Laurasia. The Indian sub-continent separated from the Gondwana collides with Eurasia and initiated the formation of the Himalayas ranges. The two giant continents (Gondwanaland & Laurasia), then moved- a part east and west thereby resulting in the opening of the Atlantic Ocean.