Major and trace elements and rare earth elements and X-ray diffraction analyses were conducted on stone harvesting knives from the Shimonokata Site and Yakenosyo Site as well as the Tateiwa Sites. Additionally, analyses were performed on gravels of red purple mudstone from the Wakino Subgroup, Kanmon Group in the northern Kyushu. The stone harvesting knives are made from a combination of red purple - gray mudstone and very fine sandstone including calcic concretions. Red purple mudstones from the Yakiyama River indicate higher Ni content, higher total rare earth elements content and lower As content than that of red purple mudstones from the Murasaki River. This suggests that it is possible to detect differences in the source of the stone materials by using these chemical compositions. Chemical compositions of stone harvesting knives from the Tateiwa Sites fall within the composition ranges of the Yakiyama River. This suggests that the source of the stone materials is the Sengoku Gorge area of the Yakiyama River.

The latest Pleistocene to Holocene deposits of four geologic cores, HU-SRA-2 with 12 m length, HU-SRM-1 with 28.4 m length, HU-SRM-1 with 18 m length, and HU-SRK-2 with 9.5 m length cores, were obtained in the lowland along the Sarufutsu River, northern Hokkaido. Diatom analysis and radiocarbon dating were performed to clarify the sedimentary environments of the core samples. The results of the diatom analysis showed the evidence of seawater inundation during the Jomon transgression in HU-SRA-2 and HU-SRM-1, but no evidence of it in HU-SRM-1 and HU-SRM-2. In addition, salinity index and the correlation between the four cores and two vicinal cores, HU-SRN-1 and AEM-1, indicated that salinity in the cores gradually strengthened at transgression and gradually weakened at regression in the Holocene. During the maximum stage (7-6.5 ka cal BP) of the transgression, brackish water area widely spread in the middle-lower area of the Sarufutsu River, attributed to the formation of barrier bars.

The damage to villages caused by the earthquake (M6.7) in northern Nagano on March 12, 2011 was concentrated along the Chikuma River on the southern slope of the Sekita Mountains. To clarify the damage, I investigated the geological survey and conducted a topographical interpretation by use of lidar images. Consequently, five gigantic landslide scars, 1-4 km in width, and three topographic depressions 1.5-3 km in width, were recognized on the southern foot of the Sekita Mountains. The reactivation of these gigantic landslides has dammed up the rivers twice on a large scale.

To consider the formation model of gigantic landslides distributed on the left bank of the Chikuma River and the Shinano River, I carried out an analysis of mineral composition of tephra beds and their stratigraphic position, to correlate them with the Shinanogawa Loam Formation.

Gigantic landslides on the southern slope of the Sekita Mountains is divided into eleven stratigraphic horizons from the Middle Pleistocene to the Holocene. I make clear the history of formation modele of the gigantic landslides.