The remains were introduced for the first time in 1901 by Dr.TSUBOI Shogoro and Dr.TORII Ryuzo of Institute of Archeology of Tokyo University, as remains of the Stone Age under the lava flow having extremely uncommon characteristics. With both doctors' works, studies on the Stone Age in island area were initiated, thus the remains can be considered as monumental remains in the field of investigations on island remains.
The remains are covered with a 5m thick of basalt lava flow. Observations on cross sections enable to identify an existence of a layer including materials from the middle Jomon period in a range of about 50cm, at a depth of about 1-2m below the lava flow. Moreover, about 2m below the layer, potteries with incised lines were collected with streaks from the initial Jomon period. Potteries, stone tools and bone tools were identified as articles from the middle Jomon period.