UNIT 6

1. UNIT6 The Earth’s structure SUBMERGED RELIEF Natural Science 2. Secondary Education

2. UNIT6 Submerged relief Submerged relief • This type of relief makes up approximately three quarters of the Earth’s surface. • We were not able to describe its characteristic features until recently: today, however, we have the technology to observe the ocean floor even at great depths. • The main features of submerged relief are continental platforms, abyssal plains, ridges and trenches. Abyssal plain Ridge Trench Continentalplatform Click on the labels to find out more Natural Science 2. Secondary Education

3. UNIT6 Submerged relief Continental platforms • Continental platforms are extensions of continents submerged in the ocean. • They are usually quite flat but get deeper the further into the sea they are. • The platform ends in a steep slope called the continental shelf. Continental shelf Continental platform Go back to the start menu Natural Science 2. Secondary Education

4. UNIT6 Submerged relief Abyssal plains • These are large plains located at great depths (normally at depths of more than 3,000 metres). They make up the largest part of the ocean floor. • Submerged mountains and volcanoes can be found here. They are sometimes so high that they form islands. Volcanic island Abyssal plain Go back to the start menu Natural Science 2. Secondary Education

5. UNIT6 Submerged relief Ridges • These are large underwater mountain ranges that are thousands of kilometres long. They cut through the abyssal plains. They can be so high that they emerge from the water and create islands, as is the case of Iceland. • Ridges have a fissure down their middle, called a rift. Rift Ridge Go back to the start menu Natural Science 2. Secondary Education

6. UNIT6 Submerged relief Trenches • These are very deep, narrow, long depressions. • The largest trenches are more than 10 kilometres deep and hundreds of kilometres long. Trench Go back to the start menu Natural Science 2. Secondary Education