It takes many geological processes - and above all time - for petrified wood to form. For millions of years, forests were covered by sediments, which meant that the trees were protected from decomposition. Due to the weight of the sediments, pressure and temperature increased - excess water was squeezed out. In order to "turn to stone", no oxygen was allowed to reach the wood. The airtight layer of sediment covers the wood like a thick, protective blanket. The trees lie wrapped up like this for what seems like an eternity. During these millions of years, however, it is not completely silent under this layer of clay, sand and volcanic ash. Water constantly seeps into the deep layers of soil and reaches the ancient tree giants. The water transports dissolved substances such as minerals into the trees. There, the cells of the wood absorb them. Gradually, the organic wood is replaced by inorganic minerals. Wood becomes stone.