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Ocean Formation, All the way through history human beings have been influenced by oceans, directly or indirectly, owing to their size as compared to the landmass. These oceans serve diverse purposes for human beings such as providing a place for waste disposal; means of transportation; providing linkages between countries for commerce and serving as sources of minerals and food. So it is very important to understand the science behind oceans, how they are formed and how they affect us (Sutherland Et al., 2012).
Oceans are also considered the lifeblood for both the humankind and planet Earth because oceans cover over three-quarters of the earth’s surface and approximately hold more than 95% of earth’s water. Oceans support human life by producing oxygen in massive quantities in the atmosphere and at the same time also help absorb excess carbon dioxide. The distance between human communities and oceans do not matter, but life is always affected by the dynamics of their relationship (Longhurst & Author, 2012).
Geological & Historical Emergence of Oceans
The history of emergence of oceans can be dated back to the formation of earth from the supernova. Due to this, from core to surface, earth originally enjoyed a homogenous density. However, with the passage of time these formless mass of particles and gas began to cool and solidify. This cooling process was interjected by frequent collisions with the space debris and meteors. As a result of this volatility and extreme environmental conditions, gases got absorbed into the molten rock and blended within the Earth’s surface (Bonnet & Woltjer, 2008).
The huge pressure exerted by earth’s numerous layers of rock held the gases within magma. However, where and when these gases or excess volatiles got in touch with the surface air, these depressurized and were aggressively released into atmosphere. Eventually the surface of the earth cooled down and formed, while the process of out gassing continued, which refers to the segregation of earth into layers of crust and mantle through the release of excess volatiles (Schaefer & Fegley, 2010). Due to the release of gasses into atmosphere, clouds began to form and after millions of years, rain was produced as the earth’s upper atmosphere began to cool down. Initially, the rain water boiled up due to exceedingly hot surface, however with the passage of time it started to cool down and water was accumulated in the form of basins, which finally led to the formation of oceans (Raymont, 2014).
Earth Components & Processes Contributing to Oceans Formation
As mentioned earlier, earth was extremely hot in the beginning owing to the collisions of planetesimals and rocks and also the decay of radioactive elements. This high temperature melted the earth’s surface and led to the formation of a hundreds of kilometres deep molten rock ocean. At this juncture, the temperatures were too high to sustain water. However, with the passage of time, temperatures cooled down and earth got divided into layers like core, mantle and crust. This was accompanied by differentiation i.e. formation of layers according to the weight and densities of their respective constituents within the first hundred million years. Resultantly, atmosphere (lightest), outer crust (heavy), mantle (heavier) and core (heaviest), were formed (Elkins-Tanton, 2012).
This development when coupled with the decrease in temperature, led to rainfalls, which in turn led to the formation of initially shallow oceans. However, when comets collided with earth, these caused huge physical disturbances leading to the development of basins of varying depth. Due to the accumulation and flow of water into these basins, oceans were formed. Other impacts were exerted by both the plate tectonics and the moon. The plate tectonics refer to the process of differentiation which is still on-going and leads to earth disposing off excess heat; while the moon’s gravity causes the earth to contract and expand, thereby causing tidal rhythms in the oceans (Rasmussen Et al., 2015).
Rising & Formation of Landmasses
The process of rising and formation of land masses led to the formation of our earth in its present form. This process initially began when the earth was experiencing differentiation and melted rocky materials lighter in weight and density were rising to the earth’s surface, cooling down and forming landmasses. These molten rocky substances were pushed up by the metals, primarily nickel and iron, sinking down owing to their heaviness and density (Miall Et al., 2015). According to another theory of formation of land masses, these were formed as a result of the volcanic eruptions deep into oceans and the molten lava accumulating and cooling down to form land masses (Alters, 2000).
No matter what theory is followed, the process of accumulation of small land masses by rising of the melted rocks continued and finally with the passage of time, their accumulation led to the formation of a massive super-continent called Pangea. The northern side of Pangea was known as Laurasia. The present-day complete Asia, Europe and North America were part of Laurasia. On the other hand, Gondwana was Pangea’s southern half and comprised of the present-day Australia, Antarctica, India, Africa and South America (Santosh, Maruyama & Yamamoto, 2009). Thereafter, for a long period of time in terms of millions of years, Pangea continued its existence in the form of a super-continent, but eventually earth’s natural forces divided this upper-continent into smaller land masses through the process of continental drift (Meert, 2012).
Continental Drift and Plate Formation & Boundaries
Continental drift basically refers to the movement of continents resulting from the motion of tectonic plates (Frisch, Meschede, and Blakey, 2010). This idea includes the processes of paleomagnetism and seafloor spreading. When two continental plates move away from each other, a rift valley is formed. This is accompanied by volcanic activities on the floor thus forming mid oceanic ridges. When an oceanic plate collides with a continental plate, the former is forced underneath the latter, a process known as subduction. This zone is characterized by volcanic and seismic activities due to the energy generated. An example is the Pacific ring of fire (Tarbuck Et al., 2014).
The process of plate formation continued to evolve as the formation of earth began. The rocky out crust of earth was not a single solid entity and was divided into massive plates that were drifting on earth’s soft mantle. The sizes of these plates kept on altering because of various physical disturbances. Currently the earth’s oceanic and continental plates include: Scotia, Antarctic, Arabian, African, South American, Caribbean, North American, Cocos, Nazca, Juan de Fuca, Pacific, Philippine, Australian-Indian and the Eurasian plates (Huggett, 2009; and Moores, Yıkılmaz & Kellogg, 2013).
While discussing continental drift and plate formation, the concept of plate boundaries is also considered relevant. These include: destructive, constructive and conservative plate boundaries. The destructive plate boundaries are also known as tensional or convergent plate margins and are formed due to the connective movement of continental and oceanic plates as oceanic plates are forced under the continental plates. Due to this movement friction heat is produced that melts oceanic plates and can result in earth quakes. During this process magma present under the plates rises up. One example of destructive plate margin is the South American Plate forcing the Nazca plate under it. Constructive plate boundaries are also known as divergent plate margins and are formed due to the plates moving apart. In such scenario, magma present under the surface rises up and forms new crust. One example of constructive plate margin is the mid-Atlantic Ridge. Lastly, conservative plates boundaries are also known as transform plate margin and are formed when two plates slide against each other in the same or opposite direction and at varying speeds. These movements can result into earth quakes. One example is the San Andreas Fault in California (Rolf, Coltice & Tackley, 2012).
Identification of Micronutrients, Abyss Plains & Seamounts
Oceans are a major source of nutrients and it is a well-known phenomenon that the type and amount of marine life depends upon the supply of three important nutrients that is silica, nitrates and phosphates. These nutrients are also called macronutrients and are present in abundant quantities in oceans. On the other hand, scientists are of an opinion that certain micronutrients are present in oceans in small quantities that also support marine life. These include iron, cobalt and zinc (Dixon, 2008).
The abyssal planes are flat expanses of the oceanic floor located next to the continental plates and are located at a depth of 10-20000 feet. However, the variation in depth is almost negligible for one abyssal plane, while its area can be in millions of square kilometres. These are generally asymmetrical in shape but their elongated shape is dictated by the continental margins. Sohm Plain in the North Atlantic Ocean is an example of abyssal plains and enjoys an area of 0.9 million square kilometres (Mulder, 2011).
Seamounts are mountains present under the surface of oceans in the form of raised seafloor. Certain seamounts (isolated mountains) called guyots, have flat tops and are extinct volcanoes that might have erupted lava at some prehistoric time when they were still active. The occurrence of sea mount takes place at the tectonic plates’ boundaries. Hawaii’s Mauna Kea is considered to be the highest sea mountain on earth and is about 30,000 feet tall, when its height is measured from the ocean floor (Charette, & Smith, 2010).
Effects of Earth’s Magnetic Field on Ocean Features
The earth’s magnetic field is generated by the molten iron rotating inside the core. This field starts from the core and extends well into the upper atmosphere to form a shield around earth against the solar winds. Once this magnetic field weakens, which is the current observation, the shield weakens and the solar winds ionize the atmosphere. Once these gaseous ions reach the oceans by way of rainfall, sometimes these induce a current in water. Once this current carrying water comes into contact with the earth’s magnetic field, disturbance of ocean currents is the obvious result (MandeaEt al., 2012).
It is also pertinent to mention that a strong magnetic field has the capability of changing salt mobility and disrupt water’s hydrogen bonding. Both these factors result into disturbance of the ocean current. Similarly, magnetic field even once weak can enhance the rate of evaporation, thereby causing disturbance of the climatic patterns (Cnossen & Richmond, 2013).
The relationship between the earth’s magnetic field and oceans also work in the opposite direction. According to recent research, the secular variation or the changes or fluctuations in the earth’s magnetic field may be the result of ocean currents. The circulatory systems amongst the seas are the result of ocean currents, as a result of which the lower layers of oceanic cold water gets transported across seas. Once the electricity carrying dissolved salts in seawater come into contact with the earth’s magnetic field, a dynamo effect is caused which in large quantum may become the reason of secular variation (Mishra, 2011).
Detail of Ocean Composition
Oceans are mostly composed of pure water and salts. For the past 1.5 billion years or so, the proportion of salts has been constant because the input and removal rates of salts are approximately equal. This has been so because the removal rate is directly proportional to the concentration of salts. Various natural removal processes include: hydrothermal vents and the removal of magnesium ions through the creation of mineral chlorite in the fissures and cracks of vents; removal of calcium ions by biogenic sediments; the burial of sediment pore-water
; and also the creation of evaporates (Thomson Et al., 2015).
In terms of composition, the seawater can be isotonic, hypertonic or hypotonic. In case of the seawater being isotonic, each 1000 ccs of it would carry 0.9grams of concentrated salts and 991ccs of pure water i.e. salts will be 9 parts per 1000. This is called isotonic because it has the same concentration as the human blood. In case of the seawater being hypertonic, each 1000 ccs of it would carry 35grams of concentrated salts and 965ccs of pure water. Hypertonic seawater is also called the oceanic solution. In case of the seawater being hypotonic, each 1000 ccs of it would carry less than 0.9grams of concentrated salts and 991ccs or more of pure water i.e. salts will be less than 9 parts per 1000 (Stichel Et al., 2012).
Seawater also carries a low proportion of nutrients i.e. phosphorous and nitrogen in the photic zone, while this proportion is quite high below 1500 feet. Seawater also carries some amounts of calcium and silicon (Stichel Et al., 2012).
Physical Properties of Seawater
Because of the composition discussed in the previous section, seawater is very much different from ordinary fresh water. Mostly, it is a lot denser than fresh water, while the hydrogen- deuterium ration is approximately 7000:1. Similarly, seawater carries more heavy isotopes as compared to fresh and rain water. This is because; most of salts and ions are left behind once the seawater evaporates into the atmosphere (Ault Et al., 2013).
In general, the physical properties or characteristics of seawater depend upon the pressure, salinity and temperature conditions. Pressure differs greatly with the changing depth of seawater and is directly proportional to it. High pressure makes water dense. Salinity also adds to the density of water because of the concentration of salts. Finally, temperature is inversely proportional to the density. Because of these variables, seawater enjoys different layers, which move with different speeds (Talley Et al., 2011).
Seawater is a water-salt solution so it also enjoys certain colligative properties. These include: osmotic pressure; boiling-point elevation; freezing-point depression and lowering of the vapour-pressure. Moreover, both the surface tension and absorption of light are lesser in seawater because of the salinity and presence of impurities. Similarly, because of the presence of ions, seawater is a better conductor of electricity than fresh or pure water (Talley Et al., 2011).
Physical Properties of Sand & Rock Formation
Sand occurs in nature in a granular form with each grain’s diameter ranging from 0.063-20 mm. According to the gran size, sand can be categorized as very fine, fine, medium, coarse and very coarse. With special reference to oceans, sand is the mechanical product of the physical processes and their physio-chemical properties differ in accordance with the properties of the original rock. Sand is also sometimes formed as result of the pyroclastic process or explosive volcanism. These processes include mainly volcanic activity leading to the creation of igneous rocks, which enjoy a distinct chemical composition. Sand is also created when rocks grind against each other as a result of physical upheavals under the surface of sea. In a slightly different dimension, sand is created as result of biological or chemical palletisation of dissolved minerals (Bell, 2013).
Most of the rocks under the seas or the bedrock are basalt. It is an igneous rock of almost black colour which carries pyroxene and plagioclase minerals. These rocks are normally formed as a result of molten lava from the volcanic activities solidifying. Basalt differs from gabbro on the basis of the grain, as their grain is finer than gabbro’s grain. Overall, three rock formation environments are responsible for the creation of basalt i.e. Most of the basalt found on Earth was produced in just three rock-forming environments: hotspots and mantle plumes under the continental plates; oceanic hotspots; and oceanic divergent boundaries (Schön, 2011).
Effects of Climate on Sea Level
In order to understand the dynamics of relationship between climatic change and sea levels, we need to look into some critical factors that are crucial. Firstly, the effects of climatic change on sea levels manifest in three main consequences that is thermohaline circulation; ocean acidification; rise in the sea level; and melting of ice sheets and glaciers (Courchamp Et al., 2014).
Thermohaline circulation constitutes a certain percentage of the overall oceanic circulation and occurs because of the variation in density caused by both the presence of fresh water and surface temperatures. It is greatly reduced owing to two main reasons, which include the increasing amounts of freshwater being introduced into sea and the melting of polar ice caps. These two not only affect the salinity levels of the oceans but also disturb deep ocean currents, circulation patterns and ocean temperatures. As far as ocean acidification is concerned, it occurs as oceans absorb increasing quantities of carbon dioxide from the atmosphere, thereby creating carbonic acid which results in the alteration of oceans’ pH levels and acidity. The process of ocean acidification directly affects the sustenance and continuity of the marine life. The rising sea levels are yet another important impact of the climate change. The sea levels are continuously rising as the increase in atmospheric temperatures is resulting into the melting of ice sheets and glaciers. Due to this factor, more water is flowing into the oceans causing a significant increase in oceanic levels thereby directly affecting life and infrastructure along the coastal areas (Pardaens, Gregory, & Lowe, 2011).
Processes & Strategies to Address Conservation of Marine Habitats, Overfishing, Global Warming Effects & Pollution
In order to sustain marine life and balance between the oceans’ components, we need to assess strategies that are being employed for the conservation of marine habitats, overfishing, global warming and pollution. First of all, the conservation of marine habitats in the UK is being looked after by the Marine Management Organisation (MMO). The responsibilities of MMO in this context include: overseeing marine related dredging, deposits and construction; devising laws for conservation of marine ecosystems; and effectively managing and countering the adverse impact of marine pollution emergencies. MMO has already implemented the conservation strategies for the east offshore and inshore, however the future direction..
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