THE DICOVERY of a NEW CONTINENT on PLANET EARTH: Zealandia

THE DICOVERY OF A NEW CONTINENT ON PLANET EARTH: Zealandia

By Vashaanth Gowri-Kriszyk, Science Editor

Recently, in February 2017, scientists have discovered a new continent called Zealandia, which includes New Zealand and New Caledonia. However, what are the continents and how many are there? How are the layers of the Earth playing a role in the formation of the continents? What are the layers of the Earth called? Read on to find out more. What are continents and what are the continental plates? The earth is split into four layers and the crust is its top layer. In the next section we would look at the layers in more depth. On Earth, in part of the crust, the world is broken into chunks called continents. Before the discovery of Zealandia, four, five, six and seven continents were accepted as the number of continents on Earth. However, prior to the discovery seven continents was the most commonly accepted number. The difference in the number of continents depend on how the continents are catagorised. For example, whether South America and North America are combined as one continent, or whether these are separated as being two continents. Furthermore, whether you have Europe and Asia grouped together as one, called Eurasia. Alternatively, Europe and Asia could be arranged as two separate continents, such as Europe and Asia. See Figure 1. for further information.

7 6 6 5 5 4

CONTINENTS CONTINENTS CONTINENTS CONTINENTS CONTINENTS CONTINENTS

1. NORTH X NORTH X X AMERICA AMERICA

2. SOUTH AMERICA X SOUTH X X AMERICA

3. AFRICA AFRICA AFRICA AFRICA AFRICA X

4. ANTARCTICA ANTARCTICA ANTARCTICA ANTARCTICA ANTARCTICA

5. AUSTRALIA AUSTRALIA AUSTRALIA AUSTRALIA/ AUSTRALIA/ AUSTRALIA (OCEANIA) OCEANIA OCEANIA

6. EUROPE EUROPE X X EUROPE X

7. ASIA ASIA X X ASIA X

AMERICA AMERICA AMERICA AMERICA

EUROASIA EUROASIA

AFRO- EUROASIA

(or Eurafrasia), Figure 1.

However, the continents in Figure 1. are not all continental plates.

Continental Plate. Where is this Continent?

Pacific In between the Nazcan, North American, South American, African and Eurasian plates.

Nazca In between the Pacific, North American, South American, and Antarctic plates.

Africa In between the Eurasian, North American, South American, Arabian, Indian and Australian plates.

Eurasia In between the African, North American, South American , Arabian, Indian and Australian plates.

North America In between the African, South American, Pacific and Eurasian Plates.

South America In between the Nazcan, Antarctic, African and North American plates.

Arabia In between the African, Eurasian and Indian plates.

India In between the Arabian, African, Eurasian and Australian plates.

Zealandia In between the Australian and the Pacific plates.

Australia In between the Indian, Pacific, Antarctic, African and Eurasian plates.

Figure 2.

KEY

Explanation: What are these

Sea: These plates are in the sea

Land: These plates are on land

The continents are moving away from each other and this is because of continental plates. Continental plates are what the land and the sea floor lie on top of. Volcanos and earthquakes are around the area where these plates connect. Here is a map which illustrates the continental plates. The light blue coloured areas on the map is sea, the black lines on the map are plate boundaries, and the remaining coloured areas on the map are land.

This is the Pacific plate. This is the Nazca plate.

Figure 3.

The plates link together and move apart creating new continents. Around 270-million years ago, there was a super-continent called Pangea. In a period of Geological Time on earth, called The Jurassic which is part of the Mesozoic era, Pangea broke up into smaller pieces. It broke into two super-continents called Gondawana (sometimes called Gondawanaland) and Laurasia. Laurasia was in the north and Gondawana in the south.

The Geological Time Scale (GTS) is a system used by Earth Scientists, for example, geologists and paleontologists, to describe the timing and relationships of events that have occurred during Earth's history. Therefore, it gives us a window into Planet Earth’s history. Please see Figure 4. for illustration. After the Mesozoic Era, in the early Cenozoic Era, the Earth changed to be how it is today.

Figure 4

What are the layers of the Earth?

The Earth is made up of different layers, and to make it easier it could be compared with the layers of an apple. See Figure 5. for an illustration of this example.

Figure 5.

The layers of the Earth have four layers and they are the crust, the mantle, the inner core and the outer core. Please see Figure 6. for illustration.

Crust Inner Core

Figure 6.

Mantle Outer Core

The top layer of the earth is what is called the crust. There are two types of crust, which are oceanic and continental crust. Continental crust is the land and about 10-70km deep, whereas, oceanic crust is under the ocean and is about 5-10km deep. This layer is solid.

The mantle is made out of two layers, which are the lower mantle and the upper mantle. The upper mantle is solid and is around 5-300 km deep. The combination of the upper mantle and the crust is called the lithosphere. The lower mantle is liquid and is sometimes called the asthenosphere. It is around 300-700km deep.

The outer core is liquid and around 700-1700 km deep. This is so hot that the pressure cannot turn it into a solid. The inner core is hotter than the outer core but the pressure of the other layers above it make it impossible for the inner core to be liquid, consequently, the inner core is solid.

Finally, think how the continents are complicated today whereas in the future they could be more complicated, as they will keep changing.