River Maruyama and River Wada are located in southern part of Boso Peninsula, Along both rivers, One Pleistocene terrace and three Holocene terrace series can be observed. Upper Holocene terrace (Maruyama I terrace) is distributed widely from the upper to lower course. By field observations of terrace deposits, Maruyama I terrace is thought to be the fluvial fill-top terrace. Only in the lower course, drowned valley had been formed and marine silt and clay with shell fragements had been deposited from about 10, 000 y. B. P. till 0, 000y. B. P., But, before the emergence of Maruyama I terrace, this drowned valley had been filled by fluvial materials from both rivers. Mid and Lower Holocene terraces (Maruyama IT and Maruyama III terraces) are distributed from the upper to lower courses. But distribution area of each terrace is smaller than that of Maruyama I terrace. From theupp er to middle course Maruyama II and III terraces are thought to be fluvial strath terraces because terrace deposits are composed of granule and sand whose thickness is less than 2m. But in the lower course those terrace are thought to be fluvial fill-top terrace because thickness of those terrace deposits is more than 5m. Those evidences show that the terrace topography of this area had been formed by three cyclic changes of depositional and erosional processes of both rivers in the Holocene. And those changes were persumed to be caused by rapid sea level rise in early Holocene and seismo-tectonical movement during the Holocene.
The purposes of this paper are to grasp the spatial structure of retail activities in the Tokyo commuting area and to consider its structure from a view point of activity space. In order to delimit the study area where commuting flows to the downtown Tokyo are dominant, principal component analysis was applied to commuting flow OD matrix of the Kanto Region. By factor analysis on the geographical matrix of cities by workers of each retailing sectors, three factors were extracted and they were interpreted as “eating and drinking services, ” “shopping goods sales” and “convenience goods sales” (Table 1). Cluster analysis was adopted to find seven types of cities in retailing activities (Fig. 2). These seven types were regrouped to three major groups, namely, CBD location group, commercial center location group, and residential area location group. The commercial location group is developed along the commuter lines, especially in sub-centers and in suburban centers. The residential location group forms three concentric zones (Figs. 3 and 4). The concept of “wedge shaped activity space” is based on consumer behavior and space cognition. It is useful to explain the spatial structure of retail activity in areas where coreoriented preference of inhabitants is quite notable. The metropolitan dominance in retailing and superiority of intervening opportunities on traffic link nodes were recognized.