Approximately ten billion years ago, a huge explosion of a gigantic mass created the scattered formation that we know as our universe. This giant explosion is known as "The Big Bang". Presently, the scattering of the universe is continuing and reverberations of the giant explosion also remain. However, in the distant future, converging around the absorption of the black holes that are generating in each particular point of the universe, this will change to a contraction in the system and eventually it is predicted that the universe will return to one large mass. This will then disintegrate again and form the universe of the next generation. It seems that the kind of process has repeated itself in the past.

　　Presently, some hundreds of billions of galaxies are scattered throughout our universe. The number of galaxies with a solar system, however, is just a small group of no more than 30, including nebulas.

　　The distance between the sun and earth is approximately 150 million kilometers. We call this one Astronomical Unit or AU for short.

　　We call the distance light can travel in a year a "Light Year". One light year is 63, 300 AUs. The galaxies that make up the universe form a slightly swelled disk shape that has a diameter of about 100,000 light years. The sun is positioned approximately 28,000 light years from the center of this circular shaped area.

　　The big bang sent scattered cosmic dust and many gases linearly through space, seemingly at the same time causing whirling vortexes of all shapes and sizes. These took the form of a substance with liquid features. It is envisaged that cosmic dust was drawn into these vortexes and by accident some kind of small clusters were formed. These small clusters then attracted further cosmic dust, thus creating even larger clusters.

　　Solar systems are formed around a large cluster known as the sun and consist of a set of planets that orbit it in a circular motion, a set of comets that orbit the sun in an elliptical motion and other small celestial bodies.

　　The earth takes a year to orbit the sun by an almost circular path that has a radius of one AU. The earth itself rotates almost once everyday, which for people in the Arctic, would be regarded as an anti clockwise rotation.

　　The sun is a fixed star that holds nine planets in its solar system that we all know from the closest to the most distant as Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Pluto is thought to be the smallest and lightest planet. The inner four planets of the solar system are relatively small, and so are called the "Terrestrial Planets" or "Earth-type planets". The four outside of these are relatively much larger planets, which are covered in heavy atmospheres, and are known as the "Jovian Planets" or "Jupiter-type planets".

　　In between Mars and Saturn there are numerous asteroids that also orbit the sun in a circular motion. Periodically, celestial bodies from these asteroids also fall on earth.

　　The earth's mass is approximately 330,000 times smaller than the sun.

　　The earth's satellite, the Moon, with its frontage always facing us, takes a month to make an orbit of our planet. Effectively it makes one full rotation during this time.

　　The planets in our solar system have long since taken a solid form, but at the beginning they were just a very cold aggregation of cosmic dust and gases that encircled it.

　　By the energy gained from their cohesion and also the various sizes and forms of celestial bodies that collided with them the planets are said to have then burnt up like fireballs.

　　Once past this stage, taking the example of the planet earth, its surface cooled off and its crust was covered by solid rock, thus signaling the beginning of the earth's fixed state.

　　This period is estimated to be approximately 4.6 billion years ago.

　　The earth's center, including radioactive heat from minerals that contain radioactivity, to this day preserves the fireball stage of the earth's development. During the period when the earth was a burning mass, the gas volatilized from within was mainly water vapor (H2O), carbon dioxide (CO2) and nitrogen (N2). This was the primitive atmosphere on earth.

　　As the surface of the earth cooled off enough to solidify, the temperature or the surrounding atmosphere also cooled. When steam exceeds the critical temperature of 274.2℃ it turns into liquid-phase water again. When it reached this state, the huge amount of water in the atmosphere turned to rain, fell onto the earths surface and formed the earth's primary ocean.

　　Earth's primary ocean is presumed to have been of a very acidic nature and estimated to have formed some 4 billion years ago. Whether the level of the ocean at this time in history was similar to that of today, or over 4 billion years, through volcanic activity, etc., that it has increased, or that much of the water was sucked in during the solidification of the earth's surface and the level has increased or so forth, is a topic for further research.

　　Amongst this primary ocean, evolved the first life on earth. The first living matter is regarded to have developed in the mud of the oceans edge. However, there remains doubt over this theory, because of the contradiction that the suns short-wave ultraviolet rays would have possibly killed off any form of life on the waters edge.

　　However, there have also been some striking recent developments in research on genes, DNA and genomes of this period. From the outcomes of research in this field, the theory that primitive life began below the depths of the seafloor has also emerged as a strong possibility. This is also an important topic for further research.

　　Recently, the theory that the first forms of life were contained amongst the celestial bodies that fell onto earth is also becoming quite an influential explanation.

　　At the present time, the most dominant theory is that the first forms of life on earth developed below the sea floor, but this has still to be determined.

　　No matter where the first life form developed, it is known that they gradually evolved from low molecular weight compounds into high molecular weight compounds. Then, purely by accident, at a certain point molecules that possessed the ability to reproduce the same molecule were formed. This was the growth of the first life form on earth.

　　Living matter possesses both self-production and metabolic functions. Firstly, evolution occurred within individual molecules, but before long molecular aggregates were also being formed. These are called single-celled or unicellular organisms. This was followed by the evolution of multi-cellular organisms.

　　Soon, new life forms began to develop one after another. Despite solid living matter being limited in existence at this stage, life forms of many varieties and classifications were generated with both long and short life spans. Life forms continued to change constantly. This change, including the falling out of existence of many life forms, is what we call evolution.

　　Although no specific period has yet been specified, probably between one to three billion years ago there was a steady increase in underwater plants like blue-green algae that contained chlorophyll, which absorbed carbon dioxide, took up carbon as nutrients and discharged the remaining oxygen into the depths of the ocean.

　　The oxygen firstly filled the submerged areas of earth and then after soon time began to be discharge into the atmosphere above the ocean and mix with the atmosphere above land.

　　At the same time, life forms that fed plants began to increase amongst the underwater living matter. These organisms absorbed the carbon dioxide within the ocean and certain kinds began to build shells of carbonated lime. The ocean also began to successively absorb the carbon dioxide in the atmosphere.

　　Until about 700 million years ago, the proportion of carbon dioxide in the atmosphere is thought to have been very large and therefore the temperature of the atmosphere and oceans to have been quite high. The decrease in the carbon dioxide in the atmosphere and the increase in oxygen would have then invited a drop in the temperature of both the atmosphere and the ocean. This then caused glacier development on earth through several large-scale "freezings" of the earth's atmosphere.

　　From this period on, the underwater plant life on earth took not only the form of blue-green algae, but also a diverse variety of other plants and organisms, and there was also a dramatic increase in the population of each variety. This is the reason why so many fossils of lime carbonate shells and bones, which settled on the seafloor during this period, remain in the earth's stratum today.

　　Preservation of life was not possible however, because the suns ultra violet rays, and in particular its short-wave length rays, destroyed the genes of organisms. Underwater, these rays penetrated to depths of about 10 meters, life forms below these depths being regarded as safe from destruction. Naturally, however, the ultra violet rays of the sun struck the surface of land directly, meaning no living matter could survive on land. This situation continued for a long time after the creation of earth.

　　The surface of land at this time in history was no doubt like that of a lifeless desert. Until about 600 million years ago, or just before, the only living matter to have existed was that below depths of 10 meters in the ocean.

　　The ultra violet rays of the sun, however, were absorbed well by oxygen. After some time, the oxygen in the ocean began to fill the area close to the ocean surface and organisms became able to live closer to the surface.

　　It is then thought that phytoplankton and zooplankton began to increase dramatically, as did the organisms that feed on them.

　　At the same time, the oxygen ejected into the atmosphere began to rise above the earth's surface and as a result of a reaction with the suns ultra violet rays, formed the ozone layer (O3) 20-60kms above the surface. The ozone layer absorbed the suns rays and in particular the short wave length rays that are harmful to living matter.

　　This put in place the environment that enabled living matter to survive on land. Before long many microorganisms and other small matter began to come ashore.

　　From approximately 450 million years ago, firstly plant life began the move onto land. This was followed by the amphibians amongst the animate members, and then of the other animate organisms and also insects.

　　From this time on, the continents and islands of the world broke out into green foliage and starting with primitive forms of bacteria, many plants and animate matter with natural characteristics made their way to shore. Through the repeated rise and fall of this matter, evolution was achieved and has continued to be achieved, up until this day.

　　Amongst this process, the evolution of human matter is a relatively recent happening. Amongst other animate matter there are also some mammals like whales and dolphins that returned to live in the sea, but in order to obtain the oxygen they require, have to place their heads out of water regularly to breathe.

　　Furthermore, underwater life also achieved evolution and has developed to become the incredibly diverse world that we know today.
　　Underwater life forms have a history of nearly 4 billion years, in comparison to life on earth, which only has a history of a little over 400 million years.

　　Throughout its history the earth's environment has provided sometimes comfortable, sometimes harsh and sometimes very rigorous conditions for living matter to survive. While a huge amount of living matter has continued to be produced throughout time, a huge amount of living matter has also gone out of existence.

　　In 1930, the worlds first refrigerant, perfectly safe for both man and animal, was developed in the United States. This was CF2Cl2 or one type of the so-called chlorofluorocarbon family. In response to efforts to raise the standard of living after the Second World War, chlorofluorocarbons were mass produced for use in originally refrigerators and air conditioning systems and then later in sprays, and the cleaning of high precision machinery.

　　In 1974, Rowland then warned the world that the risk existed that used chlorofluorocarbons ascended through the earth's atmosphere and could potentially destroy the ozone layer.

　　In 1982, Japanese and British observation teams noticed a substantial disintegration in the ozone layer above the continent of Antarctica. The United States then gained further understanding of the seriousness of the decrease in ozone when it sent up its satellite "Nimbus 7". Later in 1985 this was labeled the "Ozone Hole".

　　From 1985 a number of international deliberations were organized very promptly and by 1995 production of chlorofluorocarbons was broken off throughout the world. Thank goodness that the emergency measures taken were able to prevent the short wave length rays of the sun from pouring down on earth again and the probable extinction of all life on earth. This is one of the rare examples of a very quick response to an environmental issue by all countries of the world. This is because they could understand that it was clearly a probable scenario for the destruction of mankind.

　　In contrast, the response of countries to the dangers presented by an increase in carbon dioxide emissions through anthropogenic activities, which lead to global warming, have been varied and often very defensive. Amongst these, I think Japan's efforts have been very positive. I think that the reason for such a slow response can be put down to countries not regarding the situation as being a scenario that threatens the existence of mankind. This mayn't be a very convincing reason, but I will come back to this matter at a later time.

　　The favorable turn in the destruction of the Ozone hole is such that some researchers have predicted that the hole above Antarctica will reach its largest and most destructive size towards the end of the 20^th century, and that by the middle of the 21^st century the hole will be eradicated.

　　Similar to the topics I have mentioned thus far in this paper, it is obvious that while there are parts of the earth's environment that are quite clearly understood, there are also parts that have very hazy backgrounds and reality that is hidden away and yet to discovered. In the following parts of this paper, I would like to pass comment on a variety of these known and unknown matters.

　　The earth is the only planet in our solar system that is filled with water on its surface. Distanced further enough away from the sun so it doesn't evaporate, the earths water resources are held on its surface by a gravitational pull that is greater than the centrifugal force created by its rotation, therefore meaning it will never be plunged into the depths of outer space. In this water life was created, and after evolving it reached for land where it has prospered through to the present day. Earth is one of the truly blessed planets in the universe.

　　The solid-state earth is almost spherical in shape, with a circumference of nearly 40,000kms and a radius of approximately 6,400kms.

　　Earth consists of three components; a solid-state, an atmospheric sphere and a hydrosphere.

　　The earth's atmosphere exists as a component also held in place above land and sea by the earth's gravitational pull. The upper limit of this gravitational force extends to about 10,000 km above earth itself and sparse atmosphere exists for a further several tens of thousands of kilometers into space. The piece of space above earth that contains the actual substance of the earth's atmosphere is called the atmospheric sphere.

　　In order of their closeness to earth, this sphere is made up of the troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere. Everything else outside the exosphere is regarded as interplanetary space.

　　The state of affairs within the atmospheric sphere very quickly became clear through the use of balloons, rockets and manmade satellites.

　　The troposphere describes the first 10-20 km of atmosphere above the earth's surface. Within this sphere the atmospheres evenness, its vertical movement up and down and its composition are very fierce and the activity of steam vapor, water drops and ice clusters within the atmosphere are also quite furious. Furthermore, atmospheric conditions like clouds, rain and ascending or descending air currents are also very prominent.

　　I have already touched on the ozone layer or the stratosphere, so I won't make any further comment in this area.

　　Within the mesosphere and the thermosphere exist several ionized layers. During the day, layers D, F1, and F2 are present, during the night layers F1 and F2 join together to become layer F and layer E exists both night and day. The ionospheric layers reflect medium and short electromagnetic waves, so they can be used in long distance radio wave communications.

　　The exosphere has both an inner atmosphere and an outer one called the "Van Allan Belt". This is understood to be a highly radioactive belt that is formed when some of the protons and electrons, which are drawn into the earth's magnetic field from within solar winds, begin to fly about. The "Van Allan Belt" plays the very important role of protecting life on earth, because it absorbs the cosmic rays that constantly rain down on earth.

　　About 36,000kms above the equator, the earth's gravitational force and the centrifugal force created by its rotation cancel each other out. By launching a rocket to this point and attaching a satellite to make a one 24-hour cycle per day in a lateral direction, the satellite becomes stationary. The atmospheric satellite "Himawari" is one example of such a satellite. However, because the surrounding space isn't completely void space but in fact contains some sparse atmosphere, the resulting resistance causes the satellites speed to fall, therefore causing the centrifugal force to also fall, which in most cases then sends the satellite back into the earths atmosphere where it burns up. An alternative satellite then has to be sent up to continue the atmospheric monitoring.

　

　　I would now like to explain about Diagram 2.

　　Since the industrial revolution, mankind has consumed a massive amount of fossil fuels such as coal, oil and natural gas. The progression in medical treatment and the improvement in the distribution of the food supply since the end of the Second World War have caused an explosive increase in the population and consequently the consumption of fossil fuels has rocketed. In turn, this anthropogenic activity has invited an increase in the carbon dioxide in the atmosphere and has possibly promoted what is thought to be the phenomenon of global warming.

　　In a place of high altitude on the Island of Hawaii, American C.D. Keeling has established an atmospheric monitoring device, which has prospectively recorded an average value of the carbon dioxide in the atmosphere since 1958. Diagram 2 shows the results of this monitoring.

　

　　In addition to the yearly seasonal fluctuations, you can see there has been a progressive increase in the carbon dioxide in the atmosphere from year to year. Keeling claims that this steady increase can be put down to human activity.

　　On the basis of Keeling's pronouncement, in 1990 the Intergovernmental Panel on Climate Change (IPCC), which was established in 1988, put together an interim report that issued a warning to the world on the potential dangers of an increase in carbon dioxide emissions through human activity, the ultimate effects of global warming and the consequential rise in the sea level.

　　Being an intergovernmental panel, IPCC has much authority and it is this impact that lead to the global warming issues being taken up at following intergovernmental conferences. The issues were also made top priority at the environmental conference in Kyoto, where agreement was reached on the "Kyoto Protocol".

　　However, compared to the brisk and articulate way all countries of the world completely terminated the production of the harmful chlorofluorocarbons in order to prevent the destruction of the ozone hole, one only gets the impression that there is some lack of seriousness towards global warming.

　　Japan is particularly earnest in regards to the prevention of global warming. However, several countries situated in high latitude areas show a lack of interest in the issues. As I will explain in more detail later, this is possibly because they are more concerned with the arrival of the next glacial period. However, I believe that they are very much mistaken to adopt this approach. If global warming isn't prevented in the immediate future, I believe that civilization will no doubt be devastated sometime in the future.

　

　　Next I would like to move on to the hydrosphere.

　　The surface of earth's solid state can be separated broadly into two large parts, land and the ocean. The oceans cover 70.8% of the surface of the earth, and moreover water also exists on land in the form of lakes, rivers, underground water and glaciers. This world of water is described by the hydrosphere. The hydrosphere's volume is 98% seawater.

　　Within the earth's atmosphere, water also exists in the form of steam vapor, etc, but the volume of water the atmosphere is only 1/100,000 of the volume of the ocean. Furthermore, the circulation of water also changes the configuration of the earth's surface.

　　The average depth of the ocean is 3976 meters, or approximately 3,800 meters. The deepest point is the "Challenger Deep" of the Mariana Trench, which was discovered after the Second World War, by the English warship "Challenger". Its official depth is that recorded by the Japanese Hydrographic Department in 1989, which is internationally accepted as being 10,920±10m.

　　Of the main waters on the earth's surface, the Pacific Ocean, the Atlantic Ocean and the Indian Ocean can be regarded as the main oceans, and the Arctic Sea, the Antarctic Sea, the Mediterranean Sea, the Caribbean Sea and the Gulf of Mexico can be put forward as the main seas. Furthermore, many sea floor configurations also exist, such as the continental shelf, the continental slope, deep-sea terraces, trenches, troughs, continental rises, deep-sea plains and the Mid Oceanic Ridge System

　　Biologically, the "deep-sea" is regarded to be anything below 200 meters of the ocean. In earth science terms, however, any depth shallower than 200 meters is called "shallow water", any depth between 200 meters and 4,000 meters is called the mesopelagic zone, between 4,000 meters and 6,000 meters is known as the deep-sea and anything below 6,000 meters is called the hadal (superabyssal) zone.

　　The area covered by trenches and the hadal zone is only a very minute 1.1% of the total area of the oceans. The area between 4,000 and 6,000 meters is the largest, taking up 56.3% of the total area.

　　Incidentally, one of the natural principles of physics is that due to the influence of the earth's rotation, in the northern hemisphere gaseous or water fluids on the earths surface will deviate to the right. At higher latitudes this phenomenon is more distinct and in the opposite hemisphere the divergence is to the left. This very apparent power that works on fluids on earth is called the "Coriolis Force".

　　On the equator, the Coriolis effect is zero and fluids move perfectly straight. The Amazon River, which runs closely along the equator, runs almost straight from west to east. I believe that the Coriolis effect is the reason.

　　The atmosphere warmed near the equator ascends as it becomes lighter. At the poles, the atmosphere is chilled and descends. Therefore, if it wasn't for the rotation of the earth, near the surface of land or the ocean, cool air from the poles would flow towards the equator and warm air would move towards the poles above it. However, because of the rotation of the earth, or in other words the Coriolis effect, six wind zones exist, which run in an east to west direction.

　　In the northern hemisphere, heading north from the equator, there are the "northeast trade winds", the "westerlies", and the polar easterlies, and the "southeast trade winds", the "westerlies", and the "polar easterlies" are distributed through the southern hemisphere.

　　Distributed in between these wind zones are also the equatorial calm zone, the high-pressure zones of the mid-latitudes of both hemispheres and the high-pressure zones of the high latitudes.

　　The islands of Japan mainly fall into the "westerlies zone" of the northern hemisphere.

　　Atmospheric phenomena like low and high pressure also move slowly from west to east.

　　The friction between the winds of the various wind zones and these atmospheric phenomena are the origin to the formation of ocean current systems.

　　In the West Indian Ocean, northeastern winds that come off the Himalayan mountain ranges blow down on the region during winter, and in the summer the southwestern "Monsoon Winds" flow up through the region. Furthermore, the direction of ocean currents in the region also flows in an opposite direction, depending on the season.

　　The naming of directions between wind and ocean current are opposite. A westerly wind blows from the west to the east, but a westerly current flows from the east towards the west.

　　Winds and ocean currents are characterized by the way the flow in swirling movements, like that of whirlwinds.

　　Currents near the ocean surface often tend to form circulations in the horizontal direction and their currents are quite fast. On the other hand, they also often form circulation currents in the vertical direction.

　　Amongst the flows that exist in the ocean, another important factor is upwelling. As an example, under the influence of the Coriolis effect, the Humboldt Current, which runs north along the west coast of South America, begins to deviate away to the west somewhere off the shore of Peru. Filling in for this lack of water, the deep-sea water of the region, which is filled with the nutrients of the depths of the ocean, up wells towards the ocean surface. For this reason, this area is one of the foremost fishing grounds in the world. With such nutrients in the surface waters, the proliferation of the plankton in the area is immense, and this leads directly to a highly productive region for the fish that feed on it.

　　The circulation current that is formed by the equatorial current and the middle latitude eastward current is strongly influenced by the earth's rotation and is particularly put under pressure along the westward coasts of the Pacific and Atlantic Oceans, where it forms a very strong and fast current. This is called the "Westward Intensification" of an ocean current. The "Kuroshio Current" that runs along the Pacific coast of the western half of the islands of Japan, and the "Gulf Stream" that runs along the eastern coast of Northern America are the worlds two strongest currents.

　　The Kuroshio Current breaks away from the coast of Honshu offshore of the Kanto Region and becomes the Eastward Extension of the Kuroshio Current.

　　Filling in for this deviation in the Kuroshio Current, the "Oyashio Current flows" down along the east coast of Honshu. This kind of flow is called a "Compensation Current". Upwelling is another form of compensation current.

　　Currents that have higher temperatures than their surrounding waters are simply called "Warm Currents" and those with lower ones are respectively known as "Cold Currents".

　　Kuroshio is a warm current, while Oyashio is a cold current.

　　The Tsushima Current runs south down into the Sea of Japan through the Tsushima Strait, and then for the most part flows east into the Pacific Ocean through the Tsugaru Straits, apart from a small segment where it flows east into the Okhotsk Sea from the Soya Strait. As I will explain at a later stage, the Tsushima Current plays a key role in defining Japan's climate.

　

　　In the few years in and around 1991, from the residual amount of radioactivity from a particular radioactive substance generated from nuclear warhead experiments, etc., Wallace S. Broecker made a measurement of the age of the sea and discovered that the flow of cold and highly saline deep-sea water that had settled in the North Atlantic Ocean, had actually flowed east past the south of the Cape of Good Hope, progressed through the deep-seas of the Antarctic Sea and had not only mainly risen to the surface of the North Pacific Ocean, but also emerged partly in the surface waters of the Indian Ocean. Next he also discovered that a large circulation also existed to return the water to the North Atlantic as a low salinity surface water. This was appropriately named the "Broecker's Conveyer Belt". Its existence has since been acknowledged by the academic world. The flow of the "Broecker's Conveyer Belt" is shown in Diagram 3.

　　On the investigation of the secular change in seawater by Japan's JAMSTEC institute from carbon-14 dating, it was understood that it takes approximately 2,000 years for the circulation to flow between the North Atlantic and the North Pacific. It was then estimated that it would probably take about 6,000 years for this circulation to complete a full cycle. It has also become quite eminent that there is a strong relationship between this circulation current and the long-term climatic change of the earth.

　　Around Christmas time off the coast of Peru, the trade winds facing the east weaken, the cold upwelling currents decline and although there is a small reduction in the fishing take in the area, a much larger incidence in evaporation of the waters brings rain to the desert coastline, which enables the production of fruit and the like. This phenomenon has for a long time been known as "El Nino", and the people always applaud its arrival.

　　However, occasionally the retention of the warm current is prolonged and the delight turns to despair as the rain causes floods and destruction to the coastal communities. This was named the "El Nino Event" and is naturally despised by the people. The saying "El Nino Event" then began to stand alone in the world and developed into the famous expression that we are all familiar with today. This is because it became clear that the occurrence of El Nino was in association with the climatic change of the Western Pacific and the Indian Oceans. Its leap to fame was further realized when it was recognized also to be one of the components of climatic change on a world scale.

　　The El Nino phenomenon (in essence the "El Nino event"), which occurs at four or eight year intervals, and normally continues for one or two years, emerged several times between 1975 and 1988.

　　Additionally, there are also years when the vigor of the westward heading trade winds doesn't drop, the impetus of the strong upwelling continues and the rains don't fall on the needy coastal desert areas. Not long ago, an American scientist named this "La Nina", and in recent times it too has become a very well known saying around the world.

　　Salt substances dissolved in seawater make up 3% of its weight. However, NaCl exists in seawater in much higher proportions than any of the other dissolved substances. Over billions of years, dissolved substances have been carried with weathered rock and debris from the earth's surface and infiltrated in them as a result of underground volcanic eruptions.

　

　　As Diagram 4 shows, the earth's solid-state consists of four layers from its surface to its center, which are known as the earth's crust, the mantle, the outer core and the inner core. The earth's crust and the upper layer of the mantle are combined together and form a very rigid plate. The earths crust and the mantle consist mainly of rock. The core of the earth, however, is a very heavy layer, made up of mainly iron and also a small amount of nickel, etc.

　　The outer core remains in a liquid state, rather similar to the melted form of iron when in a high temperature smelting furnace. Moreover, it remains in a highly temperate form. The inner core, under the very high pressure of the hot outer core is in a solid form. Within the outer core there are thermal convection flows, and this explains the formation of the earth's inner and outer magnetism. Occasionally however, this heat convection stops for a small period of time. If this were to happen, the earth's magnetism would cease to exist.

　　Since the start of the 20th century, the structure of the earth's inner components has gradually become clearer and clearer through the pulses provided by both artificial and natural earthquakes. Recently, through progression in high-temperature and high-pressure experiments and developments in acoustic tomography technology, more detailed estimates can also be made.

　　In 1909, Yugoslavian M. Mohorovicic discovered the boundary between the earths crust and the mantle using the earthquake records of the Balkan Peninsula. This is called the "Mohorovicic Discontinuity".

　　The thickness of the earth's crust below the seabed was first recorded by American Maurice Ewing after the Second World War. The thickness of the earths crust is approximately 20kms on the level plains of the continents, but in some cases in mountain areas extend as far as 60kms. It is much thinner on the sea floor, however, and ranges from about 4kms-10kms in thickness.

　　The wave motions of earthquakes contain both the high sound wave velocity of longitudinal "P waves" and the low sound wave velocity of transversal "S Waves". "P Waves" move pass through both solid objects and liquids, but while "S Waves" pass through solid matter, liquids absorb them. Noting this difference in nature between the waves, the boundary between the mantle and the earth's core, and further more the outer and inner cores were discovered.

　　In 1912, Americans Beno Gutenbeg and C. Richter discovered an apparently dense surface of discontinuity, which was almost spherical in shape, about 2900km under the earth's surface. This was recognized to be the boundary between the mantle and the core of the earth. This is called the "Gutenberg Surface" or the "Ricter/Gutenberg Surface".

　　Following this in 1935, Inge Lehmann a famous woman in Danish history, discovered a surface of discontinuity at about 5100km below the earth's surface, where the velocity of the "P Wave" suddenly changed, albeit only slightly. This was the boundary between the outer and inner core of the earth and lead to the recognition of the outer core being liquid and the inner core being solid. This is known as the "Lehmann Surface".

　　This is how the structure of the earth's solid state became to be understood.

　

　　I will cover this in more detail later in this paper, but the earth's plates are a much more recent discovery, made between 1962 and 1963. The thicknesses of the plates, which are made of solid matter, are between about 60km-200km, or on average about 100km. The continental plates are estimated to be thicker than those on the deep-sea floor. The plates are also called lithospheres.

　

　　Rock can be classified into three major types known as igneous rock, sedimentary rock and metamorphic rock. Furthermore, rock that is melted by high temperatures is known as magma.

　　Igneous rock is magma that has been consolidated by a cooling process. Sedimentary rock is formed from rock that is exposed and weathered by nature on the earth's surface and then turned into small rock fragments or fine sand particles, which are then carried by rivers, etc. to mainly lake or ocean floors, where they are consolidated. Metamorphic rock is formed by rock from deep in the earths inner, which before going as far as becoming magma, turns into a different form of rock as its constituent elements or atoms change.

　　Magma rock that has been gradually cooled deep within the earth's inners is known as plutonic rock and magma that has ascended from volcanoes, etc. to the earths surface, or close to it, and then has been suddenly cooled off is called volcanic rock.

　　Furthermore, in order of the amount of silicon dioxide contained in their structure (most to the least), there is also acidic rock, intermediate rock, basic rock and ultra basic rock.

　　In general terms, the volcanoes on the earth's continents and islands contain much quartz trachyte and andesite rock, have strong magma flow resistance and are particularly susceptible to explosive eruptions.

　　In contrast, the volcanoes that exist on the plates of the ocean floor contain mainly basalt rock, have quite a low magma flow resistance and a quieter existence, so don't erupt explosively.

　　Volcanoes close by, such as Mt. Fuji or Mt. Asama, have been formed by repeated explosive eruptions, but for example, Mt. Mihara on Izu-Ooshima Island has been created by a series of quiet eruptions.

　　It is thought that the Izushichito Islands were formed by a process similar to that of Mt. Mihara, and not the violent eruptive process like that of Mt. Fuji.

　　The islands of Japan are very characteristic of the Continental Plate. Moreover, under the Northeast of Japan lies the Pacific Plate, and under the Southwest of Japan also runs the Philippine Sea Plate.

　　Near the axis of the Japan Trench and the Nankai Trough, although there is high pressure, the temperature is low, which provides the ideal environment for the formation of high-pressure/low temperature metamorphic rock. This is mainly in the form of chrystalline schist. In contrast, under the principle axis of the islands of Japan the environment is ideal for the formation of low-pressure/ high temperature metamorphic rock. This comes mainly in the form of gneiss.

　　Table 1 shows a breakdown of the Geological Age.

　　During medieval times in Europe, it was believed that the history of the earth was only a few thousand years, and that fossils were relics of "Noah's Flood". However, Leonardo da Vinci uncovered the origins of fossils and documented them accordingly. Consequently, the real stories behind fossils began to be understood around the 16^th century.

　　The fossils of animals that prospered on earth for a relatively short time before perishing from existence also contain some of the earths strata of that period, and so their age is quite easily identified. These are called index fossils.

　　Fossils that dictate sedimentary environment, such as warm or freezing conditions and shallow or deep waters are called facies fossils.

　　From this kind of comparative fossil research, a tentative segmentation of the geological age was constructed in the first half of the 19^th century. This classification of old and new fossils is called their "Relative Age".

　　At the beginning of the 20^th century, the husband and wife pair of Pierre and Marie Curry discovered the new element "Radium" and found that it had radioactivity, could destruct with precision, and its residual radioactivity decreased over time. It was then discovered that if the amount of radioactivity in the initial formation was known and that the profile of the mineral substance (including radioactive matter) remained, the age of the geologic formation (stratum) could be calculated from the remaining radioactivity. This is called "Absolute Dating" or the "Absolute Age".

　　For example, the half life radioactivity of Uranium ²³⁸ U has been established as 4.47×10⁹ years. This can be used as an accurate timer or measurer of age.

　

　　By taking the age of minerals and index fossils from the earth's geological stratum that contains radioactivity, accurate dating for all geological matter can be determined by combining the use of relative and absolute ages. Table 1 is a classification table of the geological age of substances that have been determined through this process. In line with a constant increase in the documentation of absolute dating, the values in this table have been updated every couple of years. In the foreseeable future, I would like to think there area only going to be very detailed changes to the table, but there is the possibility that it will be corrected again to some unknown extent.

　　For example, through the increase in absolute age data, the geological age of a particular Japanese geological formation frequently undergoes correction.

　　The periods previous to the beginning of prolific fossil formation, which occurred some 540 million years ago, is grouped together and called the Precambrian Era. The periods after this, which represent the boundary line of a large change in the dispersion of life on earth, are divided into three Eras called the Paleozoic Era, the Mesozoic Era and Cenozoic Era.

　　Table 1 shows the age from the larger era through to the more detailed time periods such as X Era, Y Period, Z Epoch, etc. The geological formations that belong to these time periods are the classified as X Erathem, Y System and Z Series, etc.

　　The first period in the Paleozoic Era is the Cambrian Period, followed by the Silurian Period when living matter began to move onto land.

　　The Mesozoic Era is divided into the Triassic Period, the Jurassic Period and the Cretaceous Period and the Cenozoic Era into the Paleogene Period, the Neogene Period and the Quaternary Period.

　　The boundary between the Mesozoic Era and the Cenozoic Era exists about 65 million years back in history.

　　Within the Paleogene Period there is the Paleocene Epoch, the Eocene Epoch, the Oligocene Epoch and within the Neogene Period there is the Micene Epoch and the Pliocene Epoch. The Quaternary Period is divided into the Pleistocene Epoch and the Holocene Epoch, which are also known as the Diluvial Epoch and the Alluvial Epoch.

　　The division between the Tertiary Period and the Quaternary Period was about 1.65 million years ago and the boundary between the Pleistocene Epoch and the Holocene Epoch is regarded to be about 10,000 years ago.

　　A representative living form of the Paleozoic Era is trilobites, while dinosaurs are the most well known in the Mesozoic Era and mammals are a good representative of the Cenozoic Era.

　　The last half of the ice age falls into the Quaternary Period and it is also recognized as being the period in which human life was generated and gained prosperity.

　

　　I would now like to briefly explain about the geological structure of earth.

　　Through pressure or stretching there have been times when cracks have appeared in a block of the earth's crust. This has generated faults. Fault surfaces incline towards one of two directions. In the case that a block of the earth's crust slides down onto a fault surface, they are called "Normal Faults". These were created when a stretching force was applied to earth's surface.

　　In contrast to this type of fault, in the case when the earths crust has slid itself up on top of a fault surface, the fault is said to be a "Reverse Fault". Compressing pressures on the earth's surface have generally created these faults.

　　There are also cases when a crack in separate blocks of the earth's crust both slide laterally mutually. These are called Strike-Slip Faults. If you were to stand on one of the blocks and on viewing the other block it had slipped away to the right, it would be called a "Right-Lateral Strike-Slip Fault". Alternatively, if it slipped away to the left it would be called a "Left-Lateral Strike-Slip Fault".

　　Frequently, there are also faults that are a combination of "Normal Faults" or "Reverse Faults" and "Strike-Slip Faults".

　　There were also cases when immense pressures within the depths of the earth caused not faults to occur, but for blocks to be twisted up like candy. These are called a "Folds". Under actual circumstances, there are also cases whereby faults are contained in "Folds".

　　The history of geophysics goes back to Isaac Newton who lived between 1642 and 1727. However, the most marked progression in the physics of the earth was achieved in the 19^th century.

　　In 1883, as shown in Diagram 5, Austrian Eduard Suess claimed that in between the Carboniferous Period of the Paleozoic Era and the Jurassic Era of the Mesozoic Era, the northern continental band separated from the southern continental band, which he named Gondwana. He made this speculation because there is a difference in dispersion of the living matter of that time period. He also claimed that a paleo-sea called the Tethys Sea lay between the two continental bands.

　　Furthermore, he went on to also claim that parts of this southern continent settled down into the sea, forming the sea floor and therefore explains why the southern continental band now has a much smaller area than that of Gondwana.

　　Forty years later in 1912, German Alfred Wegener advocated the "Continental Drift Theory", for which he became famous, especially after the publication of his book on the theory in 1915.

　　Wegener's theory is pictured in Diagram 6.

　　He claimed that between the Carboniferous Period of the Paleozoic Era and the Jurassic Era of the Mesozoic Era that all the earth's land was joined and in the form of one large continent. He named this extraordinarily large continent Pangaea.

　　Wegener suggested that Pangaea began to split up in the Jurassic Era, and that each piece of the continent drifted slowly to its present position.

　　In contrast to Suess's theory, Wegener advocated that Gondwana did not fall into the sea and become the sea floor, but that Pangaea first split into a northern segment and southern segment, and that the southern segment was of the size of the present southern continents all brought together. He claims this segment then divided again and drifted into the southern positions that we know of today.

　　Wegener stated that he acquired his original inspiration from the parallel nature of both coasts of the Atlantic Ocean. Wegeners claims struck up much debate both for and against his continental drift theory. However, because there was little evidence to prove any claims on either side of the argument, the controversy remained unsettled. Today, however, his theory is widely accepted as being correct.

　　In 1928, J. Joly indicated that due to high temperatures in the mantle, 1-2cms of heat convection occurs per year, and that this was the reason why the Pangaea drifted apart.

　　In the following year, Englishman Arthur Holmes backed Joly's theory, but also advocated that a new oceanic crust was created on the upper layer of the mantle heat convection and that this pushed away both sides of the divided continent (Pangaea). This is also considered to be a correct theory. Wegener, however, had claimed that the continents slid across the ocean floor like a yacht plows through the water, without the ocean floor moving.

　　Things were now getting one step closer to the truth.

　　However, in the following year of 1930, Wegener was killed in a blizzard during research activities in Greenland. Unconsciously, the debate surrounding the continental drift theory fell away.

　　About 10 years after the end of the Second World War, three distinguished Dutch scholars by the names of Kuenen, Umbrove and Vening-Meinesz advocated the theory that continental drift was something that occurred during the creation of the solid-state of earth, and that forever after this happening the ocean floor existed peacefully in its present position, without moving. This theory also received much support.

　　However, one theory that did disappear through the outcomes of research was that of Paleomagnetism.

　　Substances that take on magnetism, such as magnetic iron ore, fall into a molten condition under high temperatures, but even when crystallization occurs through cooling, they don't immediately become magnetic. They suddenly become magnetic again when they are cooled to a certain temperature. Pierre Curie discovered this fact and the temperature where matter becomes magnetic became known as the "Curie Point".

　　Iron ore, which is formed by volcanic reactions that cause molten lava to flow down mountainsides and crystallize when cooled, suddenly becomes magnetic when it reaches the "Curie Point". However, the surrounding molten lava remains in a porridge-like state and a highly temperate condition.

　　As the molten lava continues to flow down the mountainside, the long axis of the magnetic iron ore turns and faces the earth's magnetic field. Eventually, the molten lava is further cooled and turns solid. The iron ore contained in this solid state statistically records the earth's magnetic field at that particular time, in that particular place.

　　After the Second World War, Englishman S. K. Runcorn and his group traveled the world taking advantage of this fact and collected a large amount of sample measures in order to research the change in the earth's magnetic fields from ancient times.

　　From this data, Runcorn had already worked out that the north magnetic pole had moved a considerable distance in order to reach its current position. However, in his next piece of research, when concentrating on each continent being separate, he discovered that path in which the north magnetic pole moved was different from the actual movement he had discovered previously. It was here that Rancorn and his associates recalled Wegener's continental drift theory and bringing each continent together to form Pangaea, shifted the path of the north magnetic pole accordingly. The result was almost unbelievable. The movement of the magnetic pole matched the drift of Pangaea perfectly. This event took place in 1957, putting an end to the theory of the three Dutchmen and confirming the revival of the Wegener theory.

　　During the Second World War, Harry Hess of Princeton University in America moved repeatedly through the Central Pacific Ocean as the captain of a US Navy transportation vessel. From the echo sounder measurements he recorded, depending on the waters in which they were traveling, he discovered that a number of flat peaks existed at depths between several hundred and two thousand meters. He identified these as a group of submerged volcanoes. They are known as the "Guyot" and this is also the nickname assumed by Hess on his discovery.

　　Formerly, this group of volcanoes poked their heads out of the top of the Pacific Ocean. Over a long period of time their peaks were worn down flatly by the wave motions of the area, and eventually became submerged. Coral then formed on these flat peaks, but was then wiped out by a sudden subsidence that caused the flat peaks to drop 50m across the Guyot. Considerable subsidence continued leaving the group of volcanoes further submerged.

　　At the same time, in waters where such subsidence was quieter, coral gradually began to form and became the coral reefs we know of today. Hess officially announced the existence of the "Guyot" and his ideas on its formation in 1945. Charles Darwin, who traveled around the world on English warship "HMS Beagle", put forward two very significant accounts called "The Origin of Species" and "The Origin of Coral Reefs", which formed the basis of the theory of evolution. Hess's interpretations of the "Guyot" formation are verified and supported by Darwin in the later book.

　　Between 1950 and 1952, American Edwin Hamilton carried out research on the "Guyots", extracting coral fossils from several peaks that dated back approximately one hundred million years and also several fragments of basalt that are found in the structure of oceanic volcanoes. From this research it was ascertained that the sinking of the "Guyot" began approximately one hundred million years ago in the Cretaceous Period.