Glaciers are broadly broken into continental glaciers and mountain glaciers. Within mountainous glaciers, however, there are valley glaciers that cut out U-shaped valleys as they move and cirque glaciers that cut out small-scale bowl-type shapes in the peaks of mountains and surrounds.

　　In Japan, several cirque glaciers are recognized to have existed in the Japan Alps and the Hidaka Ranges in Hokkaido. However, although it is suggested that one or two valley glaciers also existed in the Hidaka Ranges, their existence isn't distinctly recognized and no other valley glaciers are known to have existed anywhere else in Japan.

　　Presently no actual glaciers exist in Japan, but perennial snow, which is regarded as the roots of glacier formation, is common.

　　The volume of ice in mountain glaciers makes no comparison to the massive volume in continental glaciers.

　　Amongst the history of the Earth, the periods in which the earth was covered in continental glaciers are called "Great Ice Ages". Great Ice Ages are estimated to have occurred every several hundred million years on earths in a variety of periodic lengths. They can be traced back about one billion years but anything before that time hasn't been ascertained.

　　The last but most recent Great Ice Age started about 2.5 million years ago. However, we still remain in the middle of this long term process, even now.

　　In Europe, from ancient times, gravel of various shapes and sizes, which differed from the surrounding ground material, was often seen lying on the earth's surface. For along time the origin of these small pebbles was unknown and they were labeled "stray stones". In 1840, a Swiss biologist Jean Agassiz predicted from a variety of research results that a wide-ranging continental glacier had developed in historical times in Europe, taking in base and side wall rock that subsequently went under a denudation process. He suggested that the "stray stones" were formed when the rock was pulled down into the glaciers and denudated, and then were revealed when the glaciers melted. Soon after he publicly announced his theory. This was the catalyst to the progress in glacier research, and step by step it become clearer that there were a number of times that continental glaciers had covered a wide-ranging area in Europe. From this time, the periods in history in which continental glaciers developed became known as "glacial epochs" or "glacial periods". Furthermore, in between these times, warm climatic periods in which glaciers retreated became known as "interglacial periods" or "interglacials".

　　The present day can be described as being in an interglacial period, but because it is unknown whether the current climatic state of the earth will remain in its present form or whether we will be visited by another glacial period, the present period has been renamed the "post-glacial period", on the assumption that we are presently in the period after the last glacial epoch.

　　However, as I will explain in more detail later, about ten years ago it was then clearly determined that we are actually in an interglacial period. I think the "present interglacial period" is the most suitable terminology for the present day and age.

　　After much research and analyzing, it has now been determined that in the last 600,000 years there have been at least five glacial periods, four interglacial periods in between them, and now the post-glacial period (or in actual fact the present interglacial period).

　　In order of their historical age, these were named the Donau, Gunz, Mindel, Riss and Wurm glacial periods. The interglacial periods are known as Gunz-Mindel Interglacial Period, the Riss-Wurm Interglacial Period, etc.

　　A little behind that of Europe, glacier research also progressed in North America and it was discovered that similar glacial and interglacial periods, which corresponded to those in Europe, also existed historically in the North American Continent.

　　As an indicator of how far the continental glacier hung over the south of the continent, a unique name was attached to the continental glacier in the North American continent. A unique name was also attached to the interglacial period that followed. Table 2 shows the unique names given to the glacial and interglacial periods of both continents.

　　The last glacial period of the North American Continent is called the Wisconsin Glacial Period. It is frequently used in association with the Wurm Glacial Period of the European Continent.

　　The lengths of the glacial periods mentioned above were estimated to be in the range of about 500-600 thousand years. However, it was also estimated that there have been many glacial and interglacial periods before this time, and that the length of the latest Great Ice Age was most likely in the order of several million years. Accurate details, however, were unknown at this stage.

　　From various residual materials it didn't take long to estimate the peak stage of each glacial period and how far each continental glacier had covered. The bottom diagram of Diagram 16 shows the distribution of the continental glacier during its peak stage in the Wisconsin Period. The upper diagram shows the distribution of the earth's present glacial formations.

　　From this diagram you are able to see that in actual fact a thick continental glacier would have covered all of New York, London and Chicago during this time. However, a lack of numeric data on the Mindel, Wurm, Post-Glacial periods, etc. meant that scientific research a very frustrating process.

　　It was known in much earlier times that the configuration of the earth's surface was flat from the coastline heading out offshore. This was known as the continental shelf. For a long time the continental shelf was defined as an area to 200m of depth, because a lack of data lead people to believe that it only spread out to such a depth.

　　Glaciers are made up of solidified water. Moreover, despite descending down slopes, when compared to rivers and streams they are markedly slower and only move at several meters or at most several hundred meters per year.

　　The origin of the ice in glaciers is seawater. Water evaporated from the ocean forms rain and hail in the skies, which then falls on the earth's surface. In a very cold environment this rain and hail turns to snow, and begins to pile up where it falls, eventually turning into perennial snow. Glaciers are formed when this perennial snow turns to ice. The water in glaciers is trapped on land and is not often that it is allowed to return to its mother body the ocean. Furthermore, as glaciers develop, the overall volume of the seawater in the ocean decreases. For this reason, the sea level drops. Therefore, during glacial ages the sea level drops, but when the glaciers melt during interglacial periods, the sea level rises. This long-term change in the level of the ocean is called a "eustatic sea level change".

　　Once the existence of glacial and interglacial periods was established, the relationship between them and the change in the sea level was recognized, and in connection with this again, the to and forth movement of the coastline also became to be understood.

　　Next, researchers thoughts extended to the idea that the continental shelf was created through the denudation and sedimentation of material by the force of the oceans waves.

　　It was then that it was decided to undertake another investigation of the outer edge of the continental shelf. R. Dietz and W. Menard carried out the research and the results of the investigation were announced in 1951.

　　The outcome showed that the depth of the outer edge of the continental shelf was in fact not 200m, but only in the vicinity of about 120m. However, depending on the location, because the depth varied by about 20m in both directions, it was decided to determine the outer edge of the continental shelf not by depth, but by the continental slope of each region. This is when the definition of the continental shelf was corrected to the place where the seabed slope suddenly becomes steep and transforms into the continental slope.

　　In 1959, Americans J. Curray (one year later than yours truly at Scripps) and F. P. Shepard (my professor during my time at Scripps) announced the results of a numerical measurement of the change in the sea level, as a consequence of a change in the volume of continental glaciers that lay on the earth's surface, at an International Oceanographic Congress in New York. This is shown in Diagram 17.

　　Taking a sample of the sediment and bedrock from the continental shelf off the shore of Texas, from the shell fragments contained in the matter taken, they screened out the matter that made their habitat in the surf zone. They then aged the material using radioactive isotope/carbon-14 dating and gained more sample material from the surrounds of other continental regions. These results are also portrayed in Diagram 17. It shows that the material obtained in the continental shelf at a depth of about 80m was from about 18,000 years ago.

　　Curray and Shepard declared these measurements as being traces of the rise in the sea level during the post-glacial period and evidence of the stability of the sea level from 5,000-6,000 years ago through to this day. This was the first time that numerical measurements were presented in relation to the historical change in sea level.

　　Curray and Shepard continued their research and several years' later revealed data that suggested the sea level 20,000 years ago was approximately 120m lower than the present day. This is portrayed in Diagram 18.

　　The announcement of these research results set the ball rolling and soon after periodic research into the glacial, interglacial and post-glacial periods began to make very rapid progress.

　　A large part of the element carbon is ¹⁶O, but it also contains a small amount of the relatively heavy, but stable isotope ¹⁸O. It was discovered that cold seawater and lake water contain a relatively large amount of ¹⁸O, while only a relatively small amount is present in warm seawater or lake water. Furthermore, it then became better understood that the ¹⁸O/¹⁶O ratio could be used as a thermometer to measure the temperature of historical waters.

　　At the International Oceanographic Congress held in 1959, many presentations were made that showed the outcomes of historical water measurements of fossils using this method. Amongst these presentations there were also many reports on the temperate environment of flora and fauna that made their habitats near the surface of the ocean and the current surface of the earth. Many of the research results showed the fact that the earth moved into a warm period about 10,000 years ago. Consequently, the presenters of these results defined the post-glacial period to be from 10,000 years ago. A short time later, through the sample measurements taken from deep-sea ocean drilling activities and subsequent research into the comparison of carbon isotopes in the samples, it became clear that the peak stage of the "Wurm (Wisconsin) Period", the last glacial period, was about 20,000 years ago.

　　From Curray and Shepards research the sea level at this time was it was already known. It had been proved that while glaciers in the last glacial period were reaching their most developed stage only 20,000 years ago, the sea level was an incredible 120m different to that of today.

　　Going back a little in time, in 1941, derived from calculations of his research results, Yugoslavian M. Milankovitch announced that, due to the changing distances between the earth and other planets or the moon, resulting in changes in gravity, the path of the earth's orbit around the sun is subject to periodic fluctuations.

　　Milankovitch recognized five cycles of fluctuation in the earth's orbit around the sun. Table 3 shows the length of these five cycles. They are simply known as the "Milankovitch Cycles". However, for a long time after their announcement the cycles became the target of attention of other geoscientists.

　　As sample measures began to collect from the deep-sea ocean drilling activities that began in the Indian Ocean and moved on throughout the seas of the world, reflected in the historical temperatures of the ocean surface, the actual state of the glacial and interglacial periods in the earth's history were determined.

　　Amongst these discoveries, scientists noticed five cycles of fluctuation, corresponding almost exactly to Milankovitch's five cycles.

　　Of the five cycles, Milankovitch calculated the 100,000-year cycle to have the weakest fluctuation in temperature. On the contrary, however, the results from the deep-sea drilling surveys showed this cycle to have the most prominent fluctuations.

　　For this reason, up until the end of 1998, it was generally regarded that Milankovitch's calculations were incorrect. In actual fact, however, it turned out that he was correct.

　　Diagram 19 shows the temperate cycle of the glacial and interglacial periods of the latest and most recent Great Ice Age of the last 2.5 million years, which has been reconstructed from the sample measures taken from deep-sea drilling activities in the North Atlantic Ocean. This data was taken from the data compiled by Raymo in 1990, and simplified by Crowley and North in 1991. Using this data, together with other data from deep-sea drilling in the Indian Ocean, the following sequence of events was revealed.

　　The Tethys Sea was decimated as the Indian Subcontinent moved drifted up north and clashed with the Eurasian Continent. The pressure continued to be applied and to a certain degree the Indian Subcontinent subducted under the Eurasian Continent, which caused the uplifting of the Tibet and Himalayan Mountain ranges to 4,000m. This occurred approximately some two and a half million years ago.

　　This gave rise to a large change in temperature on the earth's surface and invited the start of a new "Great Ice Age".

　　The pressure continued to mount and by about 600,000 years ago the Himalayan Mountains had been uplifted a further 5,000m. For this reason, the temperature difference between the glacial and interglacial periods became more acute. This can be seen in Diagram 19.

　　The reason that Agassiz was quickly able to ascertain that a glacial/interglacial period existed some 500-600 thousand years ago, after realizing that continental glaciers existed, was probably because it was easy to recognize the amplified difference between the warm and cold periods of this cycle.

　　In 1990, Americans W. S. Broecker and G. H. Denton made a detailed analysis of deep-sea drilling samples and other material and announced Diagram 20 in the popular magazine "Scientific American". The right hand side of the diagram shows the ebb and flow of the continental ice sheets over the last 600,000 years. The Milankovitch Cycle is eminent, but the 100,000-year cycle that should be weak is shown to be distinctively strong.

　　During glacial periods, ice sheets grew gradually until they reached a stage of peak development, when suddenly the Milankovitch Cycle would cause the climatic environment to change over into a warm period and the ice sheets begin to decrease in size. The interglacial periods were quite short. Their length was probably in the order of several thousands of years, or at the most about 30,000 years.

　　Furthermore, the natural trend of the present day is that we are currently in an interglacial period, which naturally means that we can expect to be descended upon by the next glacial period. We are not a post-glacial period after all, but in actual fact are in the "present interglacial period".

　　Diagram 21 has been taken from the right hand side of Diagram 20.

　　Diagram 22 shows the climatic change in surrounding Greenland. This was estimated from the amount of ¹⁸O contained in the ice drilled from the peak of Greenland's continental ice sheets. This is the research of W. Dansgaard and others, who made public their results in 1993.

　　It is now an established fact that during cold periods the heavy ¹⁸O contained in carbon descends in the ocean very quickly. Therefore, inversely, only a small amount of it was able to reach the glaciers. As explained previously, this is the indicator of the temperate conditions.

　　The drilling into the continental ice sheets of Greenland reached down to 3,000m below the surface of the ice sheet into bedrock. At this distance below the surface the ice was estimated to be from 260,000 years ago. The left column of Diagram 22 shows the drilling results down to 1,500m below the peak of the ice sheet, which was adjudged to be from about 10,000 years ago. This shows that since 10,000 years ago the warm climate has remained mostly unchanged and the temperature stable. However, the right-hand column of the diagram shows that between 260,000 years ago and 10,000 years ago there was a very intense fluctuation in temperature.

　　Many winds flow through the Greenland region, so it is justified to say that it reflects the global climate. However, at the International Oceanographic Congress in 1959, there was enough evidence put forward to suggest that the last 10,000 years was actually a "post-glacial period".

　　Between 11,000 and 13,000 years ago, it is well known that the "Younger-Dryas Mini Cold Period" existed. It can also be seen in Diagram 22.

　　I have also previously explained the "Broecker's Conveyer Belt" or the large seawater circlation shown in Diagram 3, which is quite closely related to the process I am about to explain.

　　In 1989, Broeker, Kennett and others predicted the following process had occurred. They suggested that after passing through the peak development in the Wisconsin Glacial Period, at a stage when the "Laurentide Ice Sheet" that covered the North American Continent was beginning to shrink, the glacial lake "Agassiz", which formed as a result of the melting ice sheets, fed into the Gulf of Mexico. However, when the water level of the lake rose so much that it broke its banks, which were solidified by the eastern ice and gravel, a substantial amount of the cold glacial lake water on the surface flowed out into the North Atlantic Ocean, as shown in Diagram 23. As a result, the "Broecker's Conveyer Belt" process was temporarily aborted by the cold, but light, fresh water. Consequently, the North Atlantic Ocean fell victim to a period of cold temperate conditions, which invited the "Younger-Dryas Period". However, this cold period didn't last long, because the banks of Lake Agassiz recovered quite quickly and everything returned to its previous state.

　　This sequence of events is also recorded in Broecker and Denton's thesis that was put together in 1990.

　　Taking a look at the column on the right-hand side of Diagram 22, it is apparent that the middle of the last interglacial period was approximately 120,000 years ago. Diagram 24 shows the results of completely different research that supports this statement. It shows the outcomes of research by J. Chappell, Akio Omura, Yoko Ota and others, which portray the changes in the sea level in the last 140,000 years and were made public in 1996.

　　From this diagram it can be ascertained that for several thousand years the sea level in the Riss-Wurm Interglacial Period was relatively stable.

　　In the present day, Antarctica accounts for 90% of the world's ice sheets, 9% cover the surface of Greenland and the remaining proportion is made up of mountain glaciers and the ice contained in the Arctic Ocean.

　　The Antarctic Continent and Greenland are not only located in very high latitudes, but the ice sheets are situated on risen land. Therefore, even though the continuously stable and warm period of the last 10,000 years has been warm enough to melt all the low-lying glaciers of Northern America, Siberia, etc. it hasn't been a warm enough temperature to melt the ice on Greenland and the Antarctic Continent.

　　As a result, I believe that about five or six thousand years ago, all the ice that could be melted under these climatic conditions ceased to maintain its existence, and we entered a stable period of warmth. Since 1963, I have often expressed the belief that the way human civilization has been able to continue to develop over the last five or six thousand years all lies behind the freak occurrence of this stable climatic period.

　　Even though the start of civilization may have possibly occurred in the foreshore or surrounding coastal areas before this time, I believe that by now it would be both dormant and well submerged within the continental shelf.

　　On the 164^th expedition of the deep-sea drilling research program, a place was discovered in the continental slope of the eastern Florida Peninsula where traces have been left by a large scale slide in the sea floor that was supposedly caused by the break down of the gas hydrates that existed in a frozen condition, some time in history. This was announced in 1996 and is shown in Diagram 25. The chief researchers aboard the deep-sea drilling research vessel at the time were Charles K. Paul and Ryo Matsumoto.

　　On this voyage, drillings sites 994, 995 and 997 were surveyed, which lead to the acoustic exploration records and depths of the drilling holes shown in Diagram 26. In this location no destruction of the sea floor has occurred. However, it is from here that sample measures of gas hydrate were obtained and the bottom seismic reflector (BSR) that is the foundation of the gas hydrate layer could be distinctively recognized.

　　An acoustic reflecting surface, which runs parallel with the surface of the ocean floor and is located about 500m under the continental slope, is known to have existed since about ten years ago. This surface is known as the BSR. At first it was thought to be the surface of some geologic formation, but from the material obtained from drilling research it was discovered that it is actually a substance of sherbet ice nature, which consists of an ice and water mixture that has had a large amount of methane gas, etc. dissolved into it. Under normal temperatures and normal pressure it separates into a large amount of gas and a small amount of water. This is known as the "Gas Hydrate Layer" and it's main composite is thought to be methane. The BSR was determined to be the bottom surface of this layer and as an underground resource for the future it soon drew considerable attention.

　　Furthermore, evidence to show that raw oil and natural gas reserves often exist underneath this surface has also recently become eminent. Suddenly, the resources beneath the continental slope have been put in the limelight.

　　In 1998, in the Geological Society of America's (GSA) November edition of the "GSA Today" newsletter, American Bilal H. Haq, who will also address the conference here in Hokkaido, made a very important announcement. He claimed that when the continental ice sheets development reaches a peak in the glacial age and the sea level drops to about 120m below its present point, a physical condition leads to a massive break down of the gas hydrate layer. As a result, Haq suggests, ocean floor slips occur in high incidence across the world and the methane gas is freed from the layer. The gas swells to hundreds of times its actual mass in the form of bubbles and froth, and begins to ascend to the surface, before escaping into the atmosphere.

　　Methane gas has more than ten times the global warming capacity of carbon dioxide, so the atmosphere would have warmed quickly and caused the continental ice sheets to melt rapidly. After the very swift reduction in the size of the continental glaciers, Haq explains that there was a very short interglacial period. Haq doesn't, however, state any particular reason why the interglacial period was so short or why the continental glaciers began developing again so quickly, but leaves the issue as a topic for future research and analysis.

　　However, it is very probable that the methane gas caused a large amount of cloud formation that reduced the amount of incoming solar radiation, which put the earth back into a cold period. The glacial period would then have progressed towards its peak development stage in correspondence with the ups and downs created by the Milankovitch Cycle.

　　This series of developments is estimated to have taken 100,000 years. The fluctuations in the earth's path of orbit may well explain some of the reasons for the 100,000-year cycle, but the overwhelming cause behind the length of the cycle actually lay within the continental slope of the earth's surface. This was a great discovery, which makes our present situation clear. Left to its own devices, in several thousands of year's time, the cold solidification of the earth's surface will naturally start again, in the form of the next glacial period after the 100,000-year cycle.

　　It would probably be best to assume that all the world's natural scientists and to a certain extent industry, the bureaucratic sector and the political world are very much aware of this discovery and its consequences. It may only have been announced three years ago, but it is very quickly becoming the extended knowledge of all those on earth.

　　I believe that this is one reason why the attitude of countries towards addressing increased carbon dioxide emissions and the resulting global warming issues that face our planet are far from enthusiastic, when compared to the way the issues related to the prevention of the ozone hole were approached.

　　What I would like to emphasize at this point, is that we must do everything in our power to prevent any further global warming.

　　Under the average temperature of earth's atmosphere that has remained continuously stable for 10,000 years, and favored by the fact that the dispersion of the continental ice sheets is discontinuous, the ice caps of Antarctica and Greenland that lie on raised land in their respective arctic zones have not yet to melted. On the other hand, however, in the period up to 5,000 or 6,000 years ago, the ice caps that lay on the lowlands of high latitude countries such as Siberia, Alaska and Canada have almost completely been melted away.

　　The sea level is currently within a period of several thousands of years of stability. The development of civilization and the rapid increase in the world's population can be conceived as being indebted to this stability.

　　In the last Great Ice Age of approximately 2.5 million years in duration, the constant fluctuation of the sea level was a very normal occurrence. This is a fact. Even the most stable periods were only in the order of several thousands of years.

　　This natural process is very likely to continue into the future.

　　If global warming continues, leading to a rise in the average temperature of the earth's atmosphere, and the situation progresses as far as causing the ice caps of Greenland and Antarctica to melt, the world will be filled with disaster. Assuming that the ice caps were to completely melt, it has been estimated that the sea level would rise by an enormous 70 meters. This is of course an extreme example, but a rise of several meters could easily occur. If this were to happen we would either have to abandon our coastal cities and communities, ports and harbors, and fertile lands, or try to respond by building dykes and protection walls. River drainage would be poor, so embankments would have to be raised, and port and harbor facilities would have to be made into floating structures.

　　For the meantime, we must control human induced carbon dioxide emissions. Then, additionally we must use natural forms of energy and promote research into how to maintain the current temperate state of our planet. The apparition of some genius in this field is greatly desired.

　　However, even if the countries of the world were to succeed in reducing carbon dioxide emissions, etc. and prevent global warming, it is predicted that the earth's natural processes will invite the next glacial period sometime within the next few thousand years. Eventually, just like that of 20,000 years ago, London, Hamburg, Chicago, New York, and many other leading cities in the world will be buried beneath thick glacial formations. This is something that we really need to prevent. It is in with this view, that since year before last I have begun researching a proposal to construct a new "Great Wall" in low latitude oceans, in order to guide the earth into the maintenance, or may be even the improvement, of the warm climatic conditions in the present interglacial period.

　　As can be seen in Diagram 27, my proposal is to line up many platforms that absorb the suns energy or reflect such energy out of the earth's atmosphere. The platforms would be anchored to the sea floor and would be suitably placed in waters of low latitude. This would appropriately generate the warm weather required to maintain a continuous interglacial period and effectively perform the role of preventing any global warming or global cooling.

　　Undoubtedly, such a plan would require a huge amount of financial investment. However, in comparison to the immense amount of money that would be required to realize the possibility of living on another planet, I believe it would be a very economical project.

　　Furthermore, the launching of not only stationary communication satellites above the equator, but also fixed satellites designed to target the sun's energy, could also aid such a project. Devices could be attached to such satellites to concentrate the transport of the sun's energy down to the surface of the earth.

　　A thousand years to find out about the true formation of the earth. The next one thousand years to design the "New Great Wall" and then the next couple of thousand years to build it. If this sort of action plan were formed, I am confident that we could prevent the next glacial period from developing. Surely we must make every effort to do what we can to help our children of the future and all coexisting living matter on our planet.

　　Despite being quite a conceptual figure, Diagram 28 was designed to show those living in Japan, just what a godsend the geographical location of the Sea of Japan is during this Great Ice Age.

　　At the present time we are in an interglacial period and the sea level is rising. The warm Tsushima Current passes through the Tsushima Strait from the south and while being twisted to the right by the Coriolis effect, is pushed up to the north along the coastline of Japan. It then mainly flows east through the Tsugaru Strait and escapes out into the Pacific Ocean. The remaining current moves north, before passing east through the Soya Strait and out into the Okhotsk Sea. During this process a large amount of evaporation into the atmosphere of the surface waters occurs, because of the current's warm nature.

　　In winter, bitterly cold and dry seasonal northwest winds, which originate from the high-pressure areas in Siberia, blow into Japan. This clashes with the evaporating surface water derived from the Tsushima Current and creates a large amount of snow. The slopes and plains of the central ridge area on the Sea of Japan side of Japan are covered in snow and it forms an area with some of the heaviest snowfalls in the world. However, because the area is not of high latitude, most of the snow melts in summer and so the formation stage of mountain glaciers is never reached.

　　Moreover, as a source of water resources, the water provided in this snow is crucially important.

　　From the other perspective, when the sea level falls during a glacial period, firstly the very narrow and shallow Mamiya Strait would become part of land, followed closely by most of the Soya Strait and the Tsugaru Strait. The Tsushima Strait would also become markedly narrower. Furthermore, the inflow of the warm Tsushima Current would decline and the Sea of Japan would become almost entirely enclosed waters. It would then freeze, making it impossible for any evaporation of surface water to occur. For this reason, despite the cold winds blowing in from Siberia, no snow formation would occur.

　　The islands of Japan are blessed by virtually no ice or snow accumulation during a glacial period, and seasonal snow during the interglacial period that may fall and collect, but never develops to the stage of becoming glacial.

　　Japan is a place that will never be covered in glacial formations and the Japanese people should never have their precious land taken from them. Unless some kind of measure is taken to prevent the course of nature, it is very likely that in few tens of thousands of years the presently prosperous cities of New York, London, Chicago, Hamburg, etc. will all be buried under thick glacial formations and all forms of habitat for both people and animals lost.

　　I would like to think that the world has entered an era of globalization in which the people of Japan, who have no fears of losing their land, can appeal to those people in New York, London, Chicago, Hamburg, who will eventually lose theirs, to seek a path of co-existence together into the future.

　　In 1980, off the coast of Yoshihara-Nyuzenmachi in the alluvial fan of the Kurobe River, which feeds into Toyama Bay on the Sea of Japan coast, local professional diver Takashi Shimoda and his group discovered the perished tree trunks shown in Photograph 2 standing on the sea floor, at a depth between 20m and 40m. Shimoda immediately contacted Professor Shoji Fujii of Toyama University. I received personal contact from Professor Fujii, and soon became part of the team that undertook a field investigation on the submerged forest, which was funded by a interim research grant from the Japanese Ministry of Education.

　　The size of the investigation was extended, but ultimately it was found that the submerged forest was at a depth range between 20m and 40m. Diagrams 29 and 30 show the waters in which the forest exists. The life of the trees was estimated as being a very short 50 years and they were discovered to be of the Alnus Japonica and Willow varieties. Similar trees were also thought to have grown in the vicinity of nearby streams, about five meters above sea level.

　　Using carbon-14 dating, the age of the trees was determined to be from between 7,500 and 10,000 years ago, as shown in Diagram 31.

　　The trees were dead, but their roots remained in the seabed. They weren't something that had been taken from somewhere and buried, and neither were they buried in an area close to the coastline of that time.

　　In a broad sense this was a "buried forest", but in a narrow meaning of the word this wasn't exactly correct. For this reason, the new terminology "Submerged Forest" was created.

　　This is the only place known to man where the existence of a seabed forest still remains from an era of low sea level, when the continental shelf was exposed to become land.

　　The depth and age relationship of this submerged forest is almost exactly consistent with the sea level rise traced by Curray and Shepard.

　　The process of preservation for the "Submerged Forest" is shown in Diagram 32.

　　Formerly, when a considerable amount of the continental shelf had become part of land, forest, bush and grasslands probably existed on the lowlands close to shore. Close off shore a sand bar was created and after some time the surrounding area formed a lagoon, killing off the trees and other plant life. The flooding of the Kurobe River carried an influx of sediment into the area, burying the lagoon and cutting off the upper section of the dead trees that remained. All that remained were the roots and trunks of the trees to a height of about 50cm.

　　Presently, due to the occasional movement of the sea floor by slips, the canyons of the sea floor in Toyama Bay are being eroded in towards the coastline. The buried tree trunks stood exposed in the sea floor close to the head of a canyon. In the next 50 years or so, this submerged forest will no doubt be eaten away by burrowing animals. However, many unexposed trees are also estimated to exist in the region.

　　In 1983 and 1986, we made public these views in the North European magazine "BOREAS" and in 1988 The University of Tokyo Press published the book titled "The Submerged Forest".

　　In 1998, off the shore of Matsutou City in Ishikawa Prefecture, which is over the western side of the Noto Peninsula from Toyama Bay, a similar discovery of perished Alnus Japonica and Willow-type trees was made on the continental shelf about 20m below the surface.

　　Carbon-14 dating showed that these trees were about 8,000 years old and were very similar to those of the coast of Nyuzen.

　　Centering around Norio Fuji, Professor Emeritus of Kanazawa University, Shoji Fujii, Professor Emeritus of Toyama University and I joined forces to form a research team, and undertook an investigation on the new discovery. The new location corresponded with the Tedori River Alluvial Fan. In relation to the previous discovery also, we predicted a probable process that forms the background to the preservation of the "Submerged Forests".

　　Under normal circumstances, during periods of rising sea level, trees, bush, grassland, etc. in moderate coastline areas are more than often broken down and cleaned away by the eroding force of coastal wave actions. However, the location of these submerged forests doesn't hold true to this generalization, because they are off shore from alluvial river fans. We have come to realize that not only are alluvial fans facing the coastline quite a unique condition that only occurs in a few places around the world, but it is also the ideal environment for preserving these buried forests.

　　The outcome of the investigation into the "Matsutou Submerged Forest" has been put together in a report published by the Matsutou City Board of Education.

　

　　I hereby bring my short thesis to a close.

　

　　I would like to dedicate my sincere gratitude to Mr. Steve R. Burson of the Ship & Ocean Foundation for his efforts to translate my original Japanese document into exquisite English.