Abstract
The frost hummocks and the frost scars, which are active periglacial landforms, develop on the crater bottom of Mt. Onamedake (1, 637m) in Akita-Komagatake volcanic groups. The vegetation in the crater is divided into three groups, Pinus pumila (A), Sieversia pentapetala (B), and Sanguisorba albiflora and Calamagrostis purpurascens (C). Well-developed frost hummocks entirely covered with dense vegetation are observed on the (C) group. The diameter and the height of frost hummocks, respectively, are 40 to 130cm and 10 to 65cm. The frost scars develop on the (B) group. The soil at the crater bottom is composed of the AK-b tephra (radiocarbon dated at 2, 770±260 yr. B, P.) erupted from Akita-Komagatake Volcano.
