In geological deposits, the tsunamis of past times are usually difficult to recognize. But in a deep -sea seedment in today’s Japan, researchers have now found very special references to such a natural disaster 115 million years ago: extensive amber deposits indicate that large quantities of tree resin were flushed far into the sea, were deformed by great forces and hardened only slowly. The most likely candidate for these forces are the water masses of a tsunamis.
Bernstein can give us insights into times long past. Usually he does this through ancient insects and parts of plants that were trapped in drops from tree resin years ago. The resin hardens within a few days in the air and preserves its freight in this way in almost unchanged form, even if it later petrifts.
Amber in the deep sea
However, regardless of such inclusions, amber can also provide indications of long -term natural disasters. “We found large quantities of amber in deep sea sediments from the early Cretaceous period,” reports a team around Aya Kubota from the Chuo University in Tokyo. The site is located in the Shimonakagawa quarry on the Japanese island of Hokkaido. When the deposits formed around 115 million years ago in the early Cretaceous period, this area was in the deep sea – an unusual place for amber, which can actually only be created in amber forests.
“The most plausible cause of the occurrence of this enigmatic amber in the deep sea are large -scale tsunamis,” explain Kubota and her colleagues. Accordingly, the huge tsunami waves probably flooded the forests in which the resin had once formed and tore it out into the sea when they returned. The tree resin lumps came to the deep sea. This is also indicated by the structure of the amber deposits found: “The amber is clearly deformed, comparable to typical deformation structures in soft sediments,” report the researchers.
At a rapid pace to the bottom of the sea
Large, flat surfaces on the former sea floor, in which amber has mixed with other components of the sediment, indicate that the resin has reached the sea floor in a viscous form. There it was soon covered by Sediment, which possibly came from a massive landslide, also triggered by the tsunami. Fluorescence analyzes also revealed the inner structure of the amber: “Horizontal edges, flame -like structures and small bubbles indicate that the resin was deformed by the water flow during deposition,” explains the research team. “These deformations of the resin took place under water.” Because without contact with the air, the material remains soft for much longer.
To do this, however, the primeval tree resin must have reached the forest to the sea floor in a very short time. “Such a faster and direct transport of terrestrial materials from the country to the ocean is possible through a tsunami,” write Kubota and her team. According to the researchers, simple storms or floods would not have been sufficient. When freezing and petrifying, the amber then preserved the traces of the natural forces, which at that time had an effect on it. However, it cannot be clearly determined whether it was one or more tsunamis.
Source: Aya Kubota (Chuo University, Tokyo, Japan) et al., Scientific Reports, DOI: 10.1038/S41598-025-96498-2