Since the first report by Teiichi TOKUDA in 1917, about 300 reports on the sand dune study had been published in Japan until 1973. Fig. 1 shows the number of the papers published during that period. A rapid increase is seen in 1963, when active researches were stimulated by an excursion organized by the Japanese Geological Collaboration. Chances for publication were given at the symposium in 1966 held by the Japanese Geological Society as well as at the Tottori Symposium in 1970 held by the Association of Japanese Geographers. In the early days, studies were concerned with the characteristics of the sand dune itself, such as the form of dune, the size of sand grains, and the velocity of sand movements. In the recent years, the primary interest has focused on the earth histories of both sand dune and surrounding regions. The influence of changes of sea level, climate and vegetation upon the formation of the sand dune have also been studied.
Many coastal sand dunes are distributed along the present strand-line of Japan. The ages of formations of those sand dunes can be classified into three types, as the Pleistocene sand dunes, “Older”and“Younger”Dunes in Holocene. The Older Dunes in Holocene were formed during the stage of the highest sea level in the Flandrian transgression, which was about 3 meters above present mean, the period of which ranged from 6, 000 to 4, 500B.P. Between approximately 3, 500 and 2, 000B.P. the sea level should have dropped about 2 or 3 meters below the present level. As a result of the regression the coastal dune (“Lost Sand Dune”) developed in off the coast of Hokuriku district, and the back marshy land was covered by the peat layer and forest which are found from the bottom of the sea present time. The peat layer continues to the humic sand layer on the top of the Older Dune. We can see these humic sand layers, which is contained archaeological remains in about 3, 500-1, 500B.P., on the Older Dunes in various places of Japan. Following about 1, 500B.P., the sea level seems to have risen briefly to a level slightly above present datum. The Young Dunes were formed along the newly submerged coastlines and overlaid the humic sand layers on the Old Dunes.
The Niigata Recent Dunes run in parallel rows along The Japan Sea Coast. They are classified into three groups (the Recent Dunes I, II and III) according to the distance from the inland, the degree of development of the humus layers, the degree of weathering of the sand and the topography. Judging from the archaeological remains it is concluded that the Recent Dunes I, II and III were formed respectively in the Early and Middle Jomon Period, in the Kofun Period, and in the Muromachi Period. Judging from the pollen analysis of the humus layers, it is estimated that the palaeoclimate in which each humus layer was formed was little different from the present climate. The mechanical analysis and the heavy mineral analysis of the sand indicate there is some difference between the Recent Dunes I, II and III and also regional variation within each row of the Dunes. It is believed that these facts show different sedimentary environment in which each group of the Recent Dunes was formed.
Some coastal sand dunes, such as the Himi, Uchinada, Katayamazu and Sanribama dunes, are distributed widely along the coast of the Japan Sea in the central Japan. I have made for about two decades research of the coastal sand dunes throughout the Japanese Islands, especially the Hokuriku district, from the view points of the age of formation of sand dunes, palaeoenvironment during the time of the formation of sand dunes and the relationship between the age of formation and change of sea-level. In this article I have proved the following six items in regard to the coastal sand dunes of the Hokuriku district: (1) Summary of some gists of the distribution, arrangement, basement and age of formation of the coastal sand dunes. (2) The age of formation of the coastal sand dunes which are distributed in the Hokuriku district is divided into seven periods as follows: First period-the Late Pleistocene Riss/Würm Interglacial age, Hiradoko stage; Second period-the late substage of the Earliest Jomonian age to the early substage of the Early Jomonian age; Third period-the late substage of the Early Jomonian age, the highest sea-level stage of the Flandrian transgression age; Fourth period-the earliest substage of the Middle Jomonian age; Fifth period-the Late Jomonian age to Yayoian age; Sixth period-the early substage of the Tumulusian age, the old tomb age, the Minor transgression age; Seventh period-the middle Muromachi age. Among them, the time when larger dunes were formed is the fourth, fifth and sixth periods. (3) Judging from the view point of relationship between the formation of the coastal sand dunes and the palaeoenvironment in the time of formation, both the palaeotemperature and palaeomoisture during the Holocene epoch were not in direct connection with the formation of the coastal sand dunes. (4) The necessary conditions for the formation of the coastal sand dunes are the following: (a) supply of sand, (b) migration of sand, and (c) sedimentation of sand. The conditions were prescribed by a position of strand line, it needs the fix of the position of the strand line for the formation of the coastal sand dunes. (5) From the view point of relationship between the change of sea-level and the formation of the coastal sand dunes, when the environment was changed topographically by the change of sea-level, a scale of sand dune may be changed by the fact that the above-mentioned three conditions are promoted or hindered under this changed environment. Roughly speaking, better conditions for the formation of sand dune may be just after the time when a sea-level changes from rising to lowering. (6) The relationship between the relative change of sea-level, the change of palaeoenvironment and the formation of the coastal sand dunes in every stage of the Holocene epoch is described in this article in the concrete.
Most of the San' in sand dunes are those of‘dune ridge’(dune on the beach ridge) type which was proposed in the essay of D.W. JOHNSON (1919). So called‘old dunes’are not the simple dunes but old dunes on the old beach ridge and beach berm which formed at +25m former sea level. These old sand deposits were covered with brown soil and dissected and excavated by the wind and stream. The old sand dunes were formed on these marine deposits and brown soil and then covered with red soil, grey clay and Daisen middle volcanic ashes. New sand dunes which formed in Holocene are well developed everywhere along sandy coast. In Kyuhin penninsula three curved beach ridge groups are clearly recognised on which three new sand dunes were developed. These new dune ridges are widespread and their zonal or linear pattern are useful for analyzing dune formation history. New dune Ia and Ib are discovered under the black sand a and b respectively along inland part of the dune pattern. The New dune IIa, IIb and IIc are found near the present shoreline. These new dunes seem to have been formed after Jomon, Heian and very recent transgressions, respectively.
Ancient Dunes along the coast of Japan Sea are distributed on the frontal edge of the coastal plain and basically restrict the formation of the plain along the coast of Japan Sea. It is believed that the formational ages of the Ancient Dunes are related to those of the terraces. The formation of the Ancient Dunes which develop widely along the coast of Japan Sea followed that of the middle terraces and this fact is observed from Northern Kyushu to Aomori Prefecture, the northernmost Honshu. In Niigata Prefecture, the Ancient Dunes develop in two horizons: the formational ages of high terrace and middle terrace. The former is Syozyojiyama sand bed. The latter is Katamachi sand bed and Banjin sand bed. Syozyojiyama sand bed consists of yellowish grey medium sand with two red soil beds. The sand bed of Ancient Dunes which correlates to Syozyojiyama sand bed has not been reported anywhere on Japan Sea coast.
In the case of the sandy coast of the Hibikinada, the west end of the mainland, I explicate in this report the process of the formation of bars and sand dunes mainly from the Archaeolo-geographic point of view. 1. The purposes of this report are as follows: To correct the formative period of the diluvial old sand dunes. To discover the bars formed by the Jomon transgression. To add the data to infer the existence of little transgression of the middle of Yayoi age. 2. There are two pleistocene coastal sand dunes, one was formed before the Göttweiger interstadial. The other is Ayaragi old sand dune, which was before the Paudolf interstadial. 3. In Holocene bars piled at the transgressions of the earliest Jomon, the early Jomon, the first half of late Jomon, the middle Yayoi and the incipient stage of Heian age, and then exposed by each later regression. Sand dunes were formed four times in Holocene; in the end of the earliest Jomon, in the second half of the late Jomon, from the end of the medieval ages to the middle of the modern ages and in the present age. The first beach ridge was formed in the earliest Jomon, the second in the first half of late Jomon and the third in the incipient stage of Heian age. The new sand dune which give the topographical change is Tomito new sand dune, which was formed from the end of the medieval ages to the middle of the modern ages.
This paper consists of the history of the formation of the sand dune region and some conditions of the sand dune forming periods and the sand fixing periods in five sand dune regions, the Fukiagehama region (in Kagoshima Prefecture), the Genkai region (in Fukuoka Prefecture), the Yahata region (in Niigata Prefecture), the Shonai region (in Yamagata Prefecture) and the Akita region (in Akita Prefecture). The following results were obtained; 1) Many of the sand dune regions are thought to have been formed after the formation of the sand bar caused by a rise of the sea level during the Jomon transgression (7, 000-5, 000y.B.P.). 2) Some buried humic sand beds are intercalated in the aeolian sand layer, and they indicates the time under the sand fixing condition. The buried humic sand beds are colored brown-dark brown-blackish brown-black, and are called the Kurosuna bed. 3) In Fukiagehama region, one Kurosuna bed and one black humic ash bed are observed. In the Genkai region, five Kurosuna beds are intercalated. They suggests that the time of the early Jomon culture period (about 5, 300C-14y.B.P.), the middle-later Jomon period (about 3, 400C-14y.B.P.), the Yayoi-Heian period (about 2, 000-1, 000y.B.P.), the Muromachi period (about 500y.B.P.) and after 500y.B.P. In the Yahata region, one Kurosuna bed is observed, and the upper aeolian sand bed covering the Kurosuna bed was supplied with the little transgression about 1, 000y.B.P. Three Kurosuna beds are intercalated in the Shonai sand dunes. After the Kohun period (about 1, 400-1, 300y.B.P.), much volume of the sand was supplied from the seacoast. The Akita region is composed of many parallel sand ridges. Between the ridges are belts of marshes or shallow lakes, which are parallel to the shoreline. These many sand ridges are grouped into three. The inner and the middle ridges were formed from the early Jomon to the late Jomon. The outer one were formed after the late Jomon, and are the largest in scale. 4) The stable period from the middle Jomon to the Kohun period was common to these regions, but in details these ages are different due to the local conditions. 5) After the Kohun period, the supply of the sand was increased through these regions.