The trajectory of a tree’s life is as unforeseeable as our own, determined as much by circumstance as intention. Like any living organism, it has its phases and difficult ages. It’s subject to environmental shifts and storms, to changing patterns of land use and arbitrary rains. A tree might be shaped by strict winds, the intimate attentions of animals, a spike of lightning striking from the sky. Fire can kill it, score its wood into a canvas of anger, germinate seeds in its shade that have lain dormant for centuries. And sometimes a tree can outlive its time, much like the preserved bodies of men that are unpacked from glaciers long after being lost.
Near the southern tip of Lesser Prespa Lake runs a seam of deep time. To walk across the fields at the edge of a village and then through a narrow, stony gorge is to step across the bed of an ancient sea. In places there are pockets of exposed shale and sheets of marl which can be opened like a book. Relic seashells are encrusted into the sediment, held in place where they were settled when the water receded some 1.8 million years ago. Amongst the leaves of ancient sediment, a library of geological time, I saw a branch poking through the shale while out walking with friends. I felt its dense weight the moment I drew the length of branch from the earth, and realised it wasn’t exactly as it appeared. It was a piece of petrified tree that I held in my hand, wood transformed to stone.
The shallow sea in this corner of Greece rose about 5.3 million years ago at the beginning of the Pliocene period, and the watery inundation ended an age of dry land that had lasted 170 million years from the final days of the Lower Jurassic. The story of the petrified tree isn’t certain, but in imagining its journey we might approximate its essence.
In all likelihood the tree died off as the sea slowly rose around it over 5 million years ago. It then fell into the brackish waters where mud and silt quickly settled around it, sealing it away from oxygen and stifling any aerobic activity that would have led to its decomposition. Instead, mineral-laden water that was seeping through the sediment of the seabed entered the tree’s cells, replacing the cellulose and lignin of the living organism, and preserving the structure of the wood in the shape it had adopted while alive.
As the Pliocene period came to an end around 1.8 million years ago the sea drained away, and the tree was transformed through a process called permineralisation. When the mineral-dense sea water suspended in the tree’s cells evaporated it left only minerals such as quartz in its place. All the tree’s organic properties were turned to inorganic stone, as though they’d stared into the eyes of Medusa in their last moments. It’s not the same alchemy often associated with fossils – when we’re witness to an impression or compression of a once-living organism – but in fact a replica of the original. The shape and form, the very structure of the tree itself, has been preserved in an enduring, stone mould. I held in my hands something that both was and wasn’t wood; I held in my hands a fragment of far time.