Abstract
Middle Pleistocene sediments of Tarumi NT Cave (abbreviated to NT Cave) yield abundant and diversified vertebrate remains. Five excavations of the cave from 1992 to 1996 have revealed the morphology of the cave and the stratigraphic sequence and lithofacies of its sediments. Although the original cave had been severely destroyed by limestone quarrying before the first excavation was started, the cave seems to have originally been fissure-like, and extended in the NE-SW direction. The sediments in the cave are divided into three layers: Layers 1 to 3. Layer 3 is the original remain-bearing bed which has not been disturbed by quarrying. This layer consists mainly of brown mud with limestone breccia, and attains at least 5m in thickness. Mammalian remains are predominant in the vertebrate remains from the sediments. A preliminary taxonomic study of the remains has revealed the following characteristics of the mammalian assemblage of the cave. The assemblage contains considerable numbers of extinct species and forms exotic to present-day Japan, as well as a number of extant species. Forest dwellers are predominant in the assemblage, and a species now distributed in the high mountains of Honshu (Sorex shinto) is also abundant. A hedgehog (Erinaceus sp.) occurs in the assemblage, and voles exclusively comprise two extinct species (Clethrionomys japonicus and Microtus epiratticepoides). The faunal characters indicate that the sediments are dated to the middle Middle Pleistocene and were deposited under forest environments considerably colder than in the present Honshu.
