The current theory regarding the evolution of the earth’s ocean is that water is present during the formation of the earth. Most of the discovered materials which was more than 4 billion years old also contained evidences of the present of water (Genda, 2016). Some scientists suggest that the water on earth emerged in the surface when steam was released in the volcanoes. Additional water emerged in the surface of the earth coming from meteorites and comets during the formation of the earth. The continuous addition of water from volcanoes and meteorites or comets led to the formation of the earth’s ocean.
The salt is the ocean mainly comes from the rocks. Rocks contain soluble materials and it dissolve in the ocean water through chemical weathering. The soluble materials also come from volcanic gases which dissolve in water through volcanic eruptions in the land or in the sea. The ocean maintains it salinity through a balanced natural processes. The continuous evaporation and freezing of water tend to increase the concentration of salts while the continuous addition of freshwater from the rivers and water cycle tend to decrease the concentration of salts. In addition, aquatic animals also take part to the balancing of the ocean’s salinity by using some of the salts to form their shells. Lastly, some of the salts also precipitate to form minerals (Merali & Skinner, 2009).
The cold air from the Polar Regions pushed the ocean current to flow from a direction pointing to the equator. However, due to the Coriolis Effect, the ocean current is deflected on the right in the Northern Hemisphere and to the left in the Southern Hemisphere. In the Northern Hemisphere, the cold ocean current from the North Pole travels along the east side of the continent and meet the northward ocean current from the equator. It forms an ocean current which flows in the clockwise direction due to the deflection of the Coriolis Effect (Merali & Skinner, 2009). In southern Hemisphere, the ocean current flows in the counterclockwise direction. In the region without continental boundaries, the west wind produced a westward continuous ocean current.
Tides are mainly caused by the gravitational pull of the moon and the sun. The gravitational pull of the moon causes the surface water on the ocean which is faced towards the moon to bulge outward. This is the main reason for the high tide on several coastal areas. On the other side of the earth, the inertial force causes the surface water on the ocean which is faced away from the moon to bulge inward (Merali & Skinner, 2009). The same interaction occurred in the gravitational pull of the sun although it is not as strong as the gravitational pull of the moon.
There is a variation in the tidal ranges due to the difference in the characteristics of the water bodies along the coastlines. Tidal ranges are small in coastlines surrounded by an open sea since the effects of the tides are distributed on the large scale. On the other hand, tidal ranges are large in coastlines which have narrow openings such as bays and estuaries (Merali & Skinner, 2009). The small water area amplifies the effects of the tides and increases the tidal ranges. In addition, the tidal changes in areas which experience high tidal ranges exceed the natural oscillations of the water.
One of the main strategies to protect land and property along the shoreline is the use of tightly packed boulders. These large structures are used to cover the shoreline or the cliff in order to protect the lands from erosion due to waves. In some cases, a strong seawall is also established also for the same purpose. These structures could withstand ocean waves. In the case of beaches, groins and breakwaters are installed to protect the shoreline from deposition and erosions. These structures are barriers which could be installed in beaches. The breakwaters are commonly installed parallel to the shoreline while the groins are installed perpendicular to the shoreline (Mimura & Nunn, 1998).
The strategies to protect land and property along the shoreline are commonly ineffective in terms of avoiding further erosion or deposition. In the case of the tightly packed boulders and seawalls, these structures could protect the shoreline from ocean waves. However, it could not withstand strong storm waves. It is also considered as an expensive strategy. In the case of the breakwaters and groins, these structures could alter the natural balance of the coastline and amplify the erosion and deposition on the adjacent shorelines or beaches. Many of the beaches around the world are suffering from extreme erosion and deposition due to the installment of the groins and breakwaters on some beaches (Mimura & Nunn, 1998).
The first type of convection cell is the Hadley Cells which are formed by circulation patterns at low-latitude. They play a major role in pushing the northeasterly winds in the Northern Hemisphere and the southeasterly winds in the Southern Hemisphere due to the deflection of the Coriolis Effect. These winds are also called trade winds. The second type is the Polar Cells which formed at the Polar Regions. It plays a major role in forming the polar easterlies which comes from the cold wind towards to the equator. The third type is the Ferrel Cells which are formed between the Polar Cells and the Hadley Cells. The Ferrel Cells play a major role in forming the northward wind which is deflected to the right by the Coriolis Effect (Merali & Skinner, 2009).
Genda, H. (2016). Origin of Earth’s oceans: An assessment of the total amount, history and supply of water. Geochemical Journal, 50: 27-42
Merali, Z., & Skinner, B.J., (2009). Visualizing Earth Science. Hoboken, NJ: Wiley.
Mimura, N., & Nunn, P. (1998). Trends of Beach Erosion and Shoreline Protection in Rural Fiji. Journal of Coastal Research, 14(1): 37-46.