During the early to middle
Jōmon period (approximately 4000 to 2500 BC), sea levels were five to six meters higher than at present, and the ambient temperature was also 2 deg C higher. During this period, the Kantō region was inhabited by the
Jōmon people, many of whom lived in coastal settlements. The
middens associated with such settlements contain
bone,
botanical material,
mollusc shells,
sherds,
lithics, and other
artifacts and
ecofacts associated with the now-vanished inhabitants, and these
features, provide a useful source into the
diets and habits of Jōmon society. Most of the 2400 known shell middens are found along the
Pacific coast of Japan. The Tsukumo Shell Mound is located on sloping land facing south near the Mizushima Sea, with an area of about 60 meters north-to-south and about 40 meters east-to-west. During the Jōmon period, this area was an inlet of the
Seto Inland Sea. In 1867, human bones were discovered during embankment construction, and several
archaeological excavations were conducted from 1915. Artifacts from the early through final Jōmon period, such as
Jōmon pottery of the late Jōmon period, were unearthed, but the most important discovery was about 170 human remains from the late Jōmon period. Most of the burial postures were in crouched positions with both hands and feet bent. The heads were oriented from northeast-to-southeast, aligned with the movement of the sun. It was also found that many skulls exhibited
ritual tooth extraction of the front incisors. Some of the burials were accompanied by various
grave goods such as shell rings, earrings, and waist ornaments as well as stone arrowheads,
dogū and bone implements. A late pottery burial of an infant was also found. The presence of many fishing hooks and stone fishing weights among the excavated items indicates that fishing activities was an important occupation of the inhabitants. The site is on private property, and is marked with a placard. Some of the excavated artifacts are displayed at the Kasaoka Municipal Folk Museum. ==See also==