当火山喷发,遮天蔽日的火山灰缓缓落下时,或当山洪暴发,滚滚的泥石流冲压而来时,巨大的树木倒入水中,埋入地下。地下水中以二氧化硅为主的矿物质逐渐充填到树干的各个细胞内,取代了其中的有机质,但是细胞壁上原有的特点保存了下来,从而变成了形似树木的化石木。 When volcanic eruptions, the shelter of ash slowly fall, or when the flash floods, billowing debris flow from the huge trees into the water, buried underground. Groundwater in the silica-based minerals gradually filled into the trunk of each cell, replacing the organic matter, but the original characteristics of the cell wall preserved, which turned into a tree-shaped fossil wood.