The concept of “the period of slope instability” (Tamura and Miura, 1968, 1971) emerged in the situation that historical-geomorphological approach had remarkably developed on terrace landforms in Japan. In order to incorporate most hillslopes which had been left behind the above development into the discussion of morphogenetic history of a river basin as a whole, it was intended to apply tephrochronology, which had also developed in its application to terracelandform chronology in Postwar Japan, to hillslopes too. K-cycle theory (Butler, 1959) and some viewpoints of climatogenic geomorphology were useful in the device of the new concept. Not so small number of empirical studies followed using the concept and they revealed that substantial changes had occurred in hillslope formation since at least the early Last Glacial in various parts of Japan, partially in coupling with the concept of “Postglacial dissection front” (Hatano, 1979). The both concepts were introduced as those which originated in Japanese geomorphology (Kaizuka and Suzuki, 1993). It is also intended to apply the two concepts to hillslope hazard prediction in place and time. It is necessary for further development of morphohistorical studies of a river basin as a whole that the periods of slope instability indicated are carefully interpreted in continuingly improved knowledge of hillslope processes and correctly correlated with other paleoenvironmental phenomena occurred in the same basin.

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From the years 2000-2002 the trees Cryptomeria japonica with a DBH of 30-85cm were observed in 69 locations in the Kanto Plain to have diminished. The distributions of these trees have been compared with the distributions indicated in previous reports of the last 30 years.
In the central part of Kanto Plain, the declining trees Cryptomeria japonica have already been cut down (degree 6). The average value of the degree of diminution has decreased in the central part of Kanto Plain. On the other hand, the degree of diminution has increased in the lowland along the Arakawa River and the Tone River in the vicinity of Kumagaya City and Maebashi City. The degree of diminution has also increased in the areas surrounding Kasumigaura Lake and Sawara City. According to a previous report about daily measured values, the summer air, polluted with SO₂ stagnates in the areas surrounding Kasumigaura Lake and Sawara City. It is therefore hypothesized that the air pollution is what has caused the decline of Cryptomeria japonica trees in the study area.
Under the conditions of the present environment, Cryptomeria japonica trees with a DBH greater than 30cm, and which declined by more than 4 degrees during the 1980's, have not recovered.

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This paper is an attempt to examine the recent changes in businesses in the International District (ID), a complex Asian ethnic enclave in Seattle, Washington, and to consider the characteristics and trends of this area focusing on its internal areal differentiation.
According to our field surveys of the ID at four different times (Aug., 1991; July, 1997; Sept., 2001; Aug., 2003), the following tendencies of ethnic business can be pointed out; 1) Chinese businesses have had full variety of businesses both in the retail and service sectors which have been mainly located in the historical core area of the ID and their number has been increasing through the survey period. 2) The number of Japanese businesses has been decreasing, but a small cluster of those has remained within the core area of the former Japantown. 3) There has been a striking growth of Vietnamese businesses in the northeast corner of the ID and this area had developed into a sizable ethnic business cluster by 2001.
It is noteworthy that we can see three different areas within the ID, each of which has a particular different developmental stage of ethnic town. The Chinatown is now considered to be an ethnic business town operating as an economic and cultural focus for a spatially dispersed ethnic community, the present Japantown can be seen as a residual core of the former large ethnic town, and the Vietnam Town has been developed from the early stage to the more mature stage of an ethnic town through the survey period. However, it should be also noted that a large new business space has been created in the southwest fringe of the ID by a non-community-based redevelopment project.

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