Tephrochronological study for Archaeological Ruins and Remains in the Izu Islands.

在伊豆群岛，史前遗迹和遗迹夹在火山沉积物中。厘清了该火山沉积物的地层学，从而考察了火山活动的盛衰和年龄。得到如下结果：1。在伊豆岛火山沉积物中发现了广布火山灰、Aira-Tn灰和K-Ah灰，并对广布火山灰进行了定义。在八州岛，在东山火山口浮石流沉积物的顶部发现了Aira-Tn火山灰。测定了浮石流的C-14年龄。在大岛的竹口遗址和八条岛的Yuhama遗址中发现了K-Ah灰烬。这两处遗址都属于绳文晚期。在伊豆群岛的火山沉积物中发现了一些玻璃灰，并进行了追踪。在不久的将来，这些tephras可以作为重要的标记tephras。

In Izu islands, prehistoric ruins and remains are sandwitched in volcanic deposits. Stratigraphy of this volcanic deposits clarifyed, thus prosperity and decay and age of the volcanic activities were examined. And obtained following results.1. Both widespread tephras, Aira-Tn ash and K-Ah ash were discovered in the volcanic deposits of Izu islands and the widespread tephras are defined.2. In Hachijo islnd, Aira-Tn ash discovered at the top of pumice flow deposits of Higashi-yama caldera. C-14 age of the pumice flow was measured.3. K-Ah ash were discovered in Takinokuchi ruins in Oshima island and Yuhama ruins in Hachijo island. Both relate with remains belongs to the latest Jomon Period.4. Some vitric ash discovered in volcanic deposits in the Izu islands and traced. These tephras could be treated as important marker-tephras in the near future.