Martins and the Miocene: time warp in a Bavarian quarry

A short version of this piece was published on Caught by the River as part of their Shadows and Reflections 2020

Bavaria, 1 August 2020. 8 am. It was Saturday, so the quarry was deserted. It was already fiercely hot, one of those days when you feel winded before it even starts. The forecast was for thirty-four degrees and the sky was relentless blue and the main pit was as smooth and sterile as a slab of halva.

On weekends and public holidays, when the big yellow machines fall silent, amateur paleontologists come to these places to dig for fossils. That’s why we were there, on the hunt.  Andreas was planning an exhibition about the prehistoric landscape of Bavaria and we were looking for exhibits. But from the get-go I was watching the clock. By eleven, I thought, the heat would be unbearable.

Leaving our bikes on a gravel bank, we climbed a steep crumbling slope, riven with run-off channels from summer downpours, dotted with dusty weeds. On the edge of a higher terrace, in the shade of a cliff, the fifteen million-year-old molasse layer was obvious, a grey-blue seam about forty inches deep.

The 15 million year old fossil layer

We chose our spot, set out our tools, put on our gloves and got to work, using a spade to dig out blocks of clay, maybe a foot square and six inches deep. Two hours, I figured, before the sun reached us.

It’s hard to get your head around geological time. If the world is roughly 4.5 billion years old, then this ribbon of clay is young, formed in the middle of the Miocene, a geological epoch that stretched from around 23 to 5 million years ago. Sifting through my brain to try to get some context, that’s way after the mass extinction of the dinosaurs 65 million years ago, and a bit before the Ice Age, which began 2.6 million years ago.

I was weighing the lump in my hands, heavy and cool to the touch, and that’s when I heard the martins. It often happens when you’re out in an unfamiliar place – you sense things for quite a while before you make sense of them. I’d been aware of something happening over my shoulder, out of focus, and a vague but constant sound. I put down the clay, and went to investigate.

Beyond a protruding stack of sandstone, a sand martin colony in a concave cliff, not yet in the sun. The grating staccato chatter never stopped as the tiny brown and white birds flew in a revolving swarm, so fleet and acrobatic, it was hard to keep track of an individual. Out and back, out and back, plucking insects from the air to feed what by then must have been their second brood of the year. Here in front of me, descendants of those dinosaurs that survived that mass extinction.

Sand martin colony

I didn’t watch for long, though. Time was ticking, so I went back to the seam.

If you’re lucky, Andreas said, the mudstone splits along its thin laminae. Following his lead, I pushed the broad blade into the block (molasse means soft), held my breath and applied gentle pressure.

The sun got higher and sweat pricked at my hairline and the martins flew out and back, out and back. We glugged our water and ate pistachios. The spoil heap grew with breakage and blocks that yielded nothing. We kept it tidy to avoid contaminating the pit below, its sand destined for construction, for concrete, mortar, render, cement, and scree.

Matter displaced and dispersed. Disruption like quarrying can work for nature. This quarry – a gash in the land – has created breeding sites for martins and bee-eaters, habitat for pioneer plants and voles, hunting ground for an eagle owl. Natural processes do it too. A beaver dam makes a whole new world. A landslide. An earthquake.

Oh, when splitting the clay goes right. Like cracking open a mold to reveal the casting. Our haul of beautiful fossils grew too. A serrated leaf, ochre mottled purple, its veins chestnut brown, perfectly delineated. What looked like the split case of a nut, burnt sienna. Three creamy yellow strips of grass. A rich rust rectangle of wood.  A smooth oval leaf, cardinal purple. Like petroglyphs, or the frescoes of Pompeii, each a perfect work of art.

Leaf fossil

Lately, researchers have calculated that solid stuff made by humans now weighs more than all the living biomass on Earth. I know this supports the idea of a new geological epoch, the Anthropocene but, apart from that, I don’t know what to make of it.  I thought of my grandmother’s small wicker chair with the mother of pearl inlay. And the shards of pottery that show up in my garden, unearthed by unseen creatures in the soil. Do they count towards that total? Would our newly dug exhibits?

Hunched over our best finds to shield them from the pounding rays, we carved away the superfluous clay and then wrapped them in protective layers of newspaper. Dry them out too fast and they crack and crumble, too slow and they get moldy and the beautiful pigments are destroyed.

When these leaves and fruit fell into the water and sank into the mud, when branches or whole trees toppled into the sediment, hominids were just a twinkle in the planet’s eye, not emerging until the end of the Miocene. I still struggle to conceptualise. John McPhee, in his 1981 book Basin and Range, used the English imperial measure of the yard as a metaphor for deep time. Taking ‘the distance from the king’s nose to the tip of his outstretched hand. One stroke of a nail file on his middle finger erases human history.’ A second stroke takes us back to our leaves, which fell in an era of mountain building. Talk about disruption! To the north of the rising Alps, a depression formed where the European plate was submerging under the African plate. Over time, this basin filled with debris brought down by the rivers, and plants colonized the resulting land.  If you were suddenly transported back, you’d recognize, more or less, a lot of the animals. Sabre-toothed tigers, pig-like omnivores, primates, the forebears of elephants, hoofed grazers, early rodents, living in the forests and expanding grasslands.

Here, in our actual hands, were actual elements of that middle Miocene landscape, ‘riparian’ plants, so-called because they grew along river margins and banks. Ancestors of plane trees, poplars and willow relatives, ginkgo and swamp cypress, exposed to the air for the first time in fifteen million years.

And there, in the sky behind us, were birds very like the birds that flew in that same landscape. The sand martin’s scientific name is Riparia riparia (‘of the river bank, of the river bank’, like a song).

This planet has been in flux since year dot. Our short lives mean we don’t see the changes, are under the illusion that our environment is stable, static. The scientists gives us glimpses of what’s really going on, and what we see is frightening. We can accept the destruction of whole mountains of Carrara marble, sandstone from India lining the pavements of London, aggregates from around the world damming the Nile or the Yangtze or the Indus, because we are the agents of change. But natural processes? Resisted, repressed, canalized, controlled, denied.

In the quarry that day, there was something magical about the layering of time, the incessant rhythm of those small winged creatures, the daily arc of the sun, the annual cycle of birds’ migration across continents, the deep time of their evolution and the suspension-in-time of the plants.

Through millions of years of churn and cataclysm, there is continuity too.

As we worked, the clock that had been ticking down in my head fell silent. And, in this weirdest of weird years, when time has alternately staggered along like a zombie and run like sand through a timer, those few hours have stayed with me, extending through the days and months, shimmering like a heat haze.

With thanks to UCL’s Dr Ruth Siddall for making sure I had my geological ducks in a row. Visit Orpiment, Ruth’s fascinating blog about urban geology, artists’ pigments, mineralogy and geoarchaeology.