Marine terraces with coral reef limestone are common in the tectonically active Ryukyu island arc and provide an important opportunity for reconstruction of late Quaternary eustasy, crustal movement and fossil coral reef formation. Takara and Kodakara islands are the northernmost coral islands with both Holocene and Pleistocene reef caps in the Pacific ocean. They are located at a decisive site to restore the paleoenvironment of Kuroshio warm current oceanic region. Both islands are situated on a tilted island shelf and seem to have been rising up periodically since the last glacial age (Eemian) at the nearly constant long-term tilting rate of 3.8×10^-8/year, due to accumulation of sudden uplift associated with major earthquakes. This tilting rate (R) is estimated from the following equation, R={(Ak-S)-(At-S)}÷15,000÷T=(Ak-At)÷15,000÷T, where A is the elevation of correlated terrace for Takara (t) and Kodakara (k) islands, T is the age of the terrace, S is the level of the paleo sea level relative to present sea level in meters, 15,000 is the distance in meters between two islands. The tilting rate should be calculated in ascending order geomorphologically to obtain the long-term rate. Pleistocene reef terraces are developed typically in Takara island, that is Nagabatake at 53 m above sea level (Barbados III), Nakabaru at 35 m a.s.l. (Barbados II), and Ohara surface at 21 in a.s.l. (Barbados I). Nagabatake formation includes subordinate deltafan gravel member (Kannon gravel, 30 m thick) accompanying eustatic sea-level rise. Nagabatake and Nakabaru reef tracts seem to have been formed as fringing reefs without moat, but Ohara surface is the erosional one cut on the former formations. Holocene terraces are distinctly developed in Kodakara island, that is Haebaru at 9.6 m a.s.l. (3,425-2,378 radiocarbon years B.P.), Tsukuridomari surface at 2.4 m a.s.l. (2,378-1,330 Y.B.P.). The separation of these two terraces took place around 2,378 Y.B.P. by the enormous seismic uplift of which interval is culculated about 10,000 years. Holocene formations in Kodakara island consist of Fuchinotomari, Haebaru (5,235-2,378 Y.B.P.) and Tsukuridomari formation (2,378-1,330 Y.B.P.) in ascending order, and Fuchinotomari formation is buried by Haebaru formation. Kodakara data showed a gentle submergence rate or an almost stillstand at present sea level in the last 3,500 years, but suggested a more rapid submergence between 3,500 and 5,500 years B.P.. Although submergence rates are different, this abrupt decrease in the rise of sea level at 3,500 radiocarbon years B.P. is recognized also in the adjacent coast of Florida. While the Holocene highest terrace of Takara and Kodakara islands was formed around 3,500 Y.B.P., the one of the southern part of Boso peninsula near Tokyo, the type locality of "Holocene submergence (Jomonian transgression)", shows the age of around 6,500 Y.B.P. The age, height and number of terrace in the last 7,000 years presumably depend on the amount of seismic uplift and the recurrence interval of earthquake rather than sea-level fluctuations in the tectonically active regions such as Japanese islands.

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The late Cenozoic crustal movements of Japanese islands are represented by the Green tuff and Island-arc movements (FuzITA, 1970). Kyushu is one of the most important regions of the late Cenozoic volcanism in southwest Japan, because it occupies the position of geologic joint between the Honshu (Japan proper) and Ryukyu arcs, which are characterized by many different volcanic activities. The volcanic activities of the Green tuff movement in Kyushu, which began in the early Miocene and terminated in the late Pliocene. These volcanism are represented by Green tuff, the Hizen dolerites, the Sobosan and first Setouchi volcanics, the Matsura basalts and other volcanics of the Tairiku (Continental) series. The volcanic activities of the Island-arc movement in Kyushu, which began in the early Pleistocene period. These volcanism are represented by the Hohi and Bungo volcanic activities, and the activities of volcanoes of the Sanin and Ryukyu series. The Hohi and Sanin volcanic activities are closely related the Honshu and Ryukyu arcs. The pyroclastics and lavas of the Hohi volcanic rocks in the early Pleistocene are widely distributed in northern and central Kyushu, which is located geologic joint between the Honshu and Ryukyu arcs. Moreover, it is conceivable that the early Pleistocene period was the immature stages of the recent island arc, and at the same time the recent trench had just constituted in this period. Distribution of the volcanoes of the Sanin volcanic series in the middle and late Pleistocene was controlled by geologic structure of two arcs, which is combination of ENE-WSW direction of the Honshu arc and NNE-SSW direction of the Ryukyu arc.

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The histological and histochemical studies were made on the organic membrane-shell of Mytilus edulis, and the results obtained were compared with the properties of the periostracums and of the conchiolin matrices of mineralized layers of normal shells of Mytilus edulis and Unio douglasiae. The laminated membranes, first produced in earliest stages of regeneration, show similar basophilic properties to the conchiolin matrices in mineralized layers. These membranes are always followed by the deposition of the brown membranous layer with quite different acidophilic properties, which are almost indistinguishable from those of the periostracums of Mytilus and Unio. Near completion of the brown membranous layer, other membranes are deposited inside it. They may be homologous to conchiolin which is the precursor to mineralization of shell not only from their ultrastructural appearance but also from their characteristic histochemical and staining properties. They become calcified with the development of the organic membrane-shell. In earliest stages of calcification, polycrystalline aggregates which are arranged in nacreous, homogeneous and prismatic architectural structures are occasionally observable at random fashion in the conchiolin membranous layer. From X-ray diffraction patterns, it appears that these aggregates are respectively composed of calcite or aragonite crystals. The above-mentioned facts indicate that a restricted region of the mantle epithelium can secrete, as well as periostracum, the calcified components of all the layers of shell, according to physiological requirement.

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Development of the accretionary prism is one of the most characteristic features of the Pacific-side slopes of the Japanese Islands. Most of the sediments of the accretionary prisms are composed of terrigenous and hemi-terrigenous materials. The boundary between the oceanic basement and overlying pelagic sediments expected at the lowermost part of the accretionary prism should be merely a conformable or an non-conformable relation. Tectonic influence of the relative movement of the continental lithosphere and the oceanic lithosphere, that is, influence of the activity of the Wadati-Benioff zone, appears as the thrust movement which cut the boundary between the oceanic basement and the overlying sediments. These thrusts extend into the accretionary prisms, and, some of them towards the surface of the sea floor. Earthquakes at intermediate depth under the continental slopes are the direct result of the movement of these thrusts. Acidic and basic magmatic intrusions penetrate some large thrust planes and sometimes these magmas carry continental and oceanic crustal xenoliths. Good examples of the exposure of these continental slope igneous rocks can be found not only on the present slope of the Japanese Islands but also in the Permo-Triassic structural belts in the islands.

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