When Europe was a Hot, Dusty Desert for 50 Million Years - My PhD in Geology
- Ollie Button
- May 30, 2021
- 4 min read
Updated: Jul 13, 2021
The European Sahara
What if I told you that once upon a time - before the rise and fall of Dinosaurs - the climatically chilly, damp, and miserable UK once experienced temperatures reaching 40°C or more, with far less rain and far more sun. Wouldn’t that be nice?
Well, probably not. Let me explain why…
There you stand, atop a dune, looking out onto the vast expanse of a hot, sub-equatorial desert. You gaze to look behind, and see the distant yet towering mountains in the south. You have travelled far in this arid rain shadow, and your mouth is dry. As you turn to continue northward, you notice the sliver-glimmering reflection of a great lake pit. Could it be true? Water, at last!
In your disbelief, you excitedly slide down the aeolian dune slip-face and follow the desiccated, scoured bed of a dried-up river. Running now, you smell the fresh scent of salt...
…wait, salt? This was supposed to be a tropical freshwater paradise!
Well, there is some good news and bad. The good news is that this isn't a salty ocean (yet). The bad news, however, it is salty, and it is definitely undrinkable.
For this was the great Silverpit Playa, a highly evaporative desert lake in the centre of the Rotliegend Basin - an arid, continental desert that is not too dissimilar from the dusty Death Valley of California, the dune fields of Arabia, or the expansive plains of the Sahara Desert. And believe it or not, but you were stood in the region stretching from the UK, through the North Sea, and extending into the Netherlands, Germany, and Poland.
The difference, however, is that this was 260 million years ago. How do we know this? Rocks.
What exactly is Geology, anyway?
“ With their four-dimensional minds, and their interdisciplinary ultra-verbal way, geologists can wriggle out of almost anything ” - John McPhee
See, many people have heard of geology. Those that have, usually know it to be the study of rocks, or when in a pub, a 'wannabe science' of 'licking rocks'.
But what does it actually mean to be a geologist? How can we use rocks as a tool to uncover the natural archive of Earth? And, perhaps more importantly, how is geology important for everyday life, and for the sustainable future that we all strive for?
This is my first blog, and these are big questions, so bear with me. For this one however, I will start with an example - my PhD in Sedimentology.
The Study of Ancient Sand
Let me take you back to the Rotliegend desert basin, 260 million years ago. I painted a dry, arid, wind-blown landscape. Dunes are prevalent, and bodies of water were either absent or too salty to drink. However, as we are all currently aware, climate can change.
This landscape was indeed subjected to ‘wetter’ conditions through time. Melting ice caps on the poles of Gondwana humidified the atmosphere, and tropical monsoonal rains along the regional mountain ranges increased the likelihood of flash-flooding.
This repetition between ‘dry’ and ‘wet’ climates can be observed in the rock record. For example, when dry desert dunes are subjected to wetter conditions, their form deflates and flattens into a damp sheet of sand. ‘Sticky’ damp flats capture silts, clays, and muds - forming a mudstone interval above the older, drier dunes below.
During a wetter climate, flood water is brought in via sheeted river systems. Although highly energetic and semi-erosive, these floods are only temporary and may be constricted within the topographic lows of a reworked dune field.
This branch of geology is called sedimentology. A creative discipline, by which ‘sedimentologists’ can build a picture for the ancient geography of a region by interpreting what they observe in the sedimentary rock record.
In the case of my Ph.D. (industry-funded, NAM), I am re-evaluating the Rotliegend in order to predict the nature, quality, and presence of subsurface reservoirs.
The Rotliegend largely sits far below the surface of northwest Europe and hosts primary targets for natural gas. For example, the Groningen Field (Netherlands) is one of the largest known accumulations of gas in the world and has sustained the Dutch grid for decades.
Additionally, these reservoirs are also important for the growing necessity of carbon capture and storage (CCS) as we transition to a more sustainable future.
Blogging on for Geoscience
And there we have it. Geology is more than just licking rocks! It’s a superpower. Our trusty hand lens is like a portal into deep time, where we can piece together the story of Earth’s past, gain a perception of our footing in this world, and understand how we can sustain future that will last.
Geology forms the foundation of billion-dollar commercial decisions. Therefore, like with any superpower, we must be wise in how we use it. For good, or for evil?
Although the planet is immensely dynamic - it is fragile, and we are on the verge of a tipping point. Petroleum geologists from around the world are coming to realise their part to play in a sustainable future, whether that be through carbon capture and storage, blue hydrogen, or other innovative strategies for sustaining our growing demand for Earth’s energy.
With these blogs, I hope to communicate the science of Geology, my passion, to a general audience. I wish to frame my blogs in a way that answers key questions in Geoscience, and how it plays an important role in the energy transition.
But also, a means to procrastinate by throwing some fancy words together! I hope you enjoy, and please, feel free to get in touch. I would greatly appreciate the feedback!
Cheers,
Ollie
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