Abstract
Pollen analytical studies were conducted on two core samples from a concave basin-like area thought to have been caused by submarine landslides, on the west slope of the Senoumi bank in Suruga Bay.
The core sample C was taken from the location at 34°44.10'N， 138°27.00'E, 582 m in depth. The core D was taken from the location at 34°43.32'N, 138°27.55'E, 489 m in depth.
Both cores consisted of obviously different two parts as the unconsolidated upper part and the subconsolidated lower part.
The fossil pollen assemblage of the upper part was characterized by dominance of Pinus (subgen. Diploxylon). That of the lower part，though，was dominated by pollen of conifer and deciduous broad-leaved trees of the cool-temperate zone in the case of the core C and pollen of Cryptomeria and Sciadopitys in the case of the core D.
The assemblage of the upper part is correlative to the pollen zone I of the deposits in the Suruga Bay4, 5). The age of this zone has been considered to be younger than 1,000 years ago.
On the other hand, the assemblage of lower part has been considered to be about the age of 7,000 years ago.
Thus，there is a deficiency of at least 6,000 years of accumulation of deposits between the unconsolidated part and the subconsolidated parts of the core samples, and it is considered to be the result of the submarine landslides of about 1,000 years ago.
