Category Earth Science

         About three-fourth of the Earth’s total surface is covered with water. Only one-fourth of Earth’s surface is land. The total area of the Earth’s surface covered by oceans comes to 361.100 million sq. km. Do you know how and when these oceans were formed?

          It is not yet fully known when oceans were formed. However, at the beginning of the formation of Earth, there were no oceans. The age of oceans has been calculated on the basis of the minerals present inside them. It is estimated that oceans were formed some time between 500 to 1,000 millions years before.

            The story of the origin of oceans is very interesting. The Earth was a giant burning fire ball at the time of its birth. Its surface was formed by molten rocks. When the Earth started cooling slowly, it was enveloped by clouds of gases. These clouds became very heavy after cooling. They started raining heavily, but the Earth’s surface was still so hot that the raindrops falling on it would evaporate and mix with the atmosphere again. This would again come down to the Earth in the form of rains. This cycle continued for millions of years. The Earth’s crust became cold and tough and the rain-water would boil no more, but the heavy down-pour continued for thousands of years. The low-lying areas of the Earth were filled up with the water of these heavy rains. These vast lakes of water on the surface of the Earth are today’s oceans. 

          Dead Sea is the only sea on earth which has no plant or animal life. It is, therefore, appropriately called Dead Sea. In fact, Dead Sea is a saline lake situated between Jordan and Israel. This is 77 km long and its breadth ranges between 5 to 18 kilometres. The water level of Dead Sea is the lowest on the Earth. It is lower than the sea-level by 396 metres. Millions of years ago the level of Dead Sea was, however, higher than the present one by 427 metres. At that time aquatic animals were living in Dead Sea. All of a sudden, there was a draught and the water of this sea evaporated. Gradually this sea acquired the present state.

          No river originates from this sea. The Jordan River and some small canals end up in this sea. Since no river comes out of this, the water of this sea depletes only by evaporation. Consequently, the amount of salt and other soluble minerals brought into the sea by the Jordan River and other smaller canals goes on increasing. You will be surprised to know that the amount of salt present in Dead Sea is the largest in comparison to the other seas. In general, the amount of salt present in any sea is 4% to 6%. But even this make you sick as it contains large quantities of magnesium chloride and other poisonous substances. Due to the presence of large quantities of salt and other poisonous materials no living being can survive in this sea. Hence fish and other acquatic animals of the Jordan River die as soon as they enter the water of this sea.

          Generally, Sea Mountains are those mountains which are at least one kilometre above the seabed. A number of such mountains have been discovered.

          Upheavals at the bottom of the sea are responsible for the formation of these mountains. Volcanic eruptions in the seabed also make mountains. Generally, these mountains are one to three kilometres high. Majority of these mountains remain submerged in water, but some of them have surfaced above also. The flat mountains coming above water are called islands. The Hawaii islands were formed in this manner.

          There are many mountains in the midst of oceans. The mid-ocean ridge is continuous and it winds for 60,000 km through all worlds’ oceans. There are many mountains in the north-east part of the Pacific Ocean. Most of these mountains are submerged in water, but some of the mountains of the Hawaiian chain have surfaced above. They are called the Hawaii Islands. The highest mountain of the Hawaiian chain is the Mauna Kea. The height of this mountain is 4,200 metres above sea level, but the total height of this mountain from the bottom of the sea is 9,686 metres. That means the height of this mountain inside the sea is 5,486 metres. If its height is taken in full, this is the highest mountain of the world.