Wood buried in the ground thousands to tens of thousands of years ago due to volcanic activity is called the age of the gods when it is accidentally unearthed due to land development, tunnels, road maintenance work, etc.
Starting with cedar, it covers all kinds of timber that was flourishing at the time, such as pine, horse chestnut, chestnut, tamo, and camphor.
Apart from volcanic activity, there are also materials deposited on riverbeds due to earthquakes, mountain tsunamis, river floods, and sea tsunamis.