田辺湾沿岸の海岸地形の形成過程と後期完新世海面変化

概要

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Relative changes of sea-level during late-Holocene time were restored in Tanabe Bay, the southwestern part of the Kii Peninsula, though geomorphological-stratigraphical analysis of erosional features such as wave-cut benches, notches and caves, and depositional ones such as raised sand bars and delta surfaces, which are developed on several levels and partially occupied by prehistoric sites of respective ages.Immediately after the highest sea-level phase which is indicated by the 6.0-6.5m benches on rocky coast, Sand bar I was developed in the middle Jomon period (around 4, 300yrs. B. P.) in the mouth of drowned river valleys at the innermost part of the bay. It was followed by the 3.5-4.0m sea-level phase indicated by the higher benches, notches and caves. The middle benches and notches. Sand bar II, and wide beaches which are developed even on rocky coast indicate the next phase of stable sea-level at 2.0-2.5m above the present level which seems to have been preceded by a regression attending to a little lower than 2m above the present. It is estimated to be around 2, 400yrs. B. P. The following rapid regression in the Yayoi period provided the sea-level lower than 2m below the present, as suggested by the facts that Sand bar I, Sand bar II and the upper delta are dissected by shallow troughs and the lower delta was formed.
東北地理学会の論文