First order landforms are the largest physical features of the Earth’s surface. These physical features are continents and ocean basins. Continents are parts of the Earth’s crust that rise above the ocean’s surface. About 30% of the Earth’s surface are continents. Ocean basins are major depressions in the Earth’s crust. Large bodies of water cover these depressions.
First Order Landforms
Continents
Continents are large areas of the continental crust. Water bodies usually surround each continent. Seven continents found on the Earth’s surface. The seven continents are: Africa, Antarctica, Asia, Australia, Europe, North America, and South America. The table below organize the continents by their sizes.
| The Continents of the World | ||
|---|---|---|
| Continent | Area (million square kilometers) | Landmass (% of total) |
| Asia | 44.6 | 29.5 % |
| Africa | 30.4 | 20.4 % |
| North America | 24.7 | 16.5 % |
| South America | 17.8 | 12.0 % |
| Antarctica | 14.0 | 9.2 % |
| Europe | 10.2 | 6.8 % |
| Australia | 8.6 | 5.9 % |
The table reveals that the largest continent is Asia. Australia is the smallest of the seven continents. The actual number of continents may vary. Europe and Asia can be combined into Eurasia. In addition, North and South America are combined into the Americas.
Ocean Basins
Ocean basins are large depressions in the Earth’s crust. The depressions lie below sea level. This means that water covers each basin. Ocean basins make up about 70% of the Earth’s surface.
Oceans cover first order ocean basins. The five oceans are the Arctic, Atlantic, Indian, Pacific and Southern Oceans.
The table below compares the oceans by their sizes.
| The Oceans of the World | ||
|---|---|---|
| Ocean | Area (million square kilometers) | Ocean Surface (% of total) |
| Pacific Ocean | 168.7 | 46.6 % |
| Atlantic Ocean | 85.1 | 23.5 % |
| Indian Ocean | 70.5 | 19.5 % |
| Southern Ocean | 22.0 | 6.1 % |
| Arctic Ocean | 15.5 | 4.3 % |
From the table above, we observe that the Pacific Ocean covers the largest ocean basin. The Arctic Ocean covers the smallest ocean basin.
Reflections
Vocabulary
- continent
- landform
- ocean basin
Notes
- Landforms are the largest physical features on the Earth’s surface.
- Continents are large landmasses that rise above the sea level. Asia is the largest continent.
- Ocean basins are landmasses that are below sea level. The Pacific Ocean covers the largest ocean basin.
