In this paper the authors intended to classify the older tephra, so-called Tama tephra and the middle or lower Pleistocene marine sediments in Oiso and Yokohama areas, southern Kanto district.
The results are summarized as follows:
(1) The older tephra in Oiso area is devided into four members, that is, Tsuchiya, Soda, Fujisawa and Zoshiki tephra. Each tephra covers conformably on the marine sediments, Nanakuni-toge, Soda, Fujisawa and Zoshiki formations respectively.
(2) Tsuchiya tephra, the uppermost member (30m in thickness) is correlated with Tsuchihashi tephra (13-8m in thickness) in Yokohama area and the Tama hills. Soda tephra (25m in thickness) is correlated with Sannodai tephra (10m in thickness) in Yokohama area.
(3) Tsuchiya tephra is covered unconformably by Kissawa formation which was deposited in the Shimosueyoshi transgression age.
Soda tephra may be covered unconformably by Nanakuni-toge formation. Zoshiki tephra are probably older than Soda formation.
(4) In Yokohama area, the marine sediment which is covered conformably by Tsuchihashi tephra may exist. However, the relation between this sediment and Totsuka formation, which is proposed by the Kanto Quaternary Research Group as the marine deposit of the post-Byobugaura and pre-Shimosueyoshi age, could not be sufficiently clarified yet.
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