“Do you see it?” said my field assistant, leaning back in his camp chair and pointing up into the night sky.
The campfire had burned down to crackling embers, its glow flickering on pale eucalypts that leaned over the creek bed where we had set up camp. Above us, the night sky was filled with brilliant starlight. The Milky Way, a sweep of light, stretched across the sky. It’s hard to imagine how spectacular the outback Australian night sky can be without seeing it. There were certainly times on geological fieldwork when I was woken in the night by the blinding light of the moon. But there were also rarer, moonless nights when I was woken by starlight.
I slumped back in my camp chair, neck resting on the canvas back, and followed the path of his outstretched arm with my eyes.
“What am I looking for?” I asked, “a constellation?”
“Sort of,” he replied. “The black space in the middle of the Milky Way. It’s an Aboriginal constellation, the Emu. Do you see it?”
When I focused on the blackness, instead of the light, I saw it, the long neck, the beaked head, plump body and legs stretching away toward the horizon, dense clouds of interstellar gas and dust concealing the light of distant stars. It is a constellation visible only in the clearest, darkest skies.
The Emu came to my mind when thinking, as I often do these days, about the converging ways in which we are increasing our use of that other dark space that so few of us ever see – the Earth beneath our feet – the hidden darkness underground, the subsurface.
I was thinking about this at the launch of the European geo-energy atlas last week, the first harmonized view of European data on geothermal energy and geological carbon storage potential and a key output of the Geological Service for Europe project. When presenting the new atlas, the project lead for this work Maayke Koevoets (TNO), showed an image of borehole and well data for Europe, one of the key data sources for the atlas. The map of Europe she showed seemed completely swamped by little coloured dots representing the locations of boreholes and wells. Indeed, there are more than 2 million of them in EuroGeoSurveys’ borehole database, delivered through the European Geological Data Infrastructure. Millions of drilled holes, windows into the darkness. From some, water has been extracted, from some, rock cores – thin tubes of rock that show us exactly what is under the ground. Others have been used to measure properties of the hidden subsurface – temperature, water levels, resistivity, radioactivity, density. Boreholes and wells, Maayke noted, are not just crucial for understanding where we can find geothermal energy and where we can store carbon dioxide underground but are relevant to all aspects of how we understand and use the subsurface – groundwater management, geohazard mitigation, infrastructure planning, finding mineral resources.
For me, the borehole and well database of Europe has always been one of those datasets that’s just been there, in the background, though of course it hasn’t – many people actually put a lot of work into building it. And with my apologies to those who did all that work, it doesn’t seem super exciting. But it occurred to me, seeing those millions of coloured dots on the screen during the atlas launch, how important this kind of information is – boreholes and well data, geophysical data, geological models. If we want more renewable energy, more geological carbon storage, more mineral resources, better groundwater management, better mitigation of floods, drought, landslides, subsidence. If we want all this, then we need more and better understanding of the darkness that few of us ever think about, beneath our feet.
In the Wonder podcast, which explores planet Earth for curious minds, geologist Holly Cooke recounted a childhood memory of lying on the ground and looking up at the night sky filled with stars. She couldn’t shake the feeling that lying there, she was actually pinned against the ceiling of the world, looking down into the darkness and a million points of light. If I imagine us the other way up, like Holly did, I can re-picture those millions of boreholes and wells as points of light in the sky, windows of data and information reaching into the darkness.
