Active Volcano Mt. Yakedake Corner
Active volcano Mt. Yakedake (2,455 m)
Location where the buried trees were found
We can see part of trees that lived here about 2,350 years ago!
Trees unearthed from the deposit of the Nakao Pyroclastic Flow
A volcano repeats a period of energetic eruptive activity and a period of relatively sedated activity through its supposed life of several hundred thousand years. The Nakao Daira highland was formed as the pyroclastic flow or mud flow caused by an eruption of Mt. Yakedake ran down along the Senzoku Gorge. One of Mt. Yakedake's pyroclastic flow events that recently occurred is the Nakao Pyroclastic Flow. The shards of magma and volcanic ash that erupted from the mountain were piled up to a depth of 40 to 50 m.
These Japanese white pine trees were found in 1971 from a cliff (shown withmark in the photo) shaved by a river for a very long time out of the Senzoku Gorge buried by the Nakao Pyroclastic Flow. Age determination revealed that these trees were alive about 2,310 years ago (as of 1971). It means the Nakao Pyroclastic Flow was an event that occurred about 2,350 years ago. When the trees were found, they showed almost no sign of corrosion and were put on display as a valuable evidence to describe the history of Nakao Daira. However, as the trees were kept exposed to air for many years, they came to be deteriorated. As a solution, the trees were entirely coated with resin and have been on display beyond access of hand touch since then.
① Senzoku Gorge about 2,350 years ago.
② The Nakao Pyroclastic Flow buried the gorge.
③ As a mountain stream flows down, the gorge gradually increase its depth.
④ Japanese white pipe (Pinus parviflora), whitch grew about 2,350 years ago, suddenly emerges!