Scanning the Stromatolite Barcode

“9-to-5”: these 3 little words have always given me heeby-jeebies. I envisaged a fulfilling career as a light-hearted nomad with a geological hammer and compass walking the heart of inaccessible wild mountain peaks while catching a whiff of fresh breeze and Alpine sunshine.  This romantic appeal has driven me through all the report-writing workload during the undergraduate Geology course and motivated me to get the most from four years at St Andrews.

I felt extremely fortunate when my application for the Laidlaw fellowship offered an opportunity to marry my long-term life goals of wild exploration to cutting-edge research at St Andrews.  My supervisor, Dr Timothy Raub, and I agreed that I would do geological mapping on the iconic island of Islay, most famous for the spectacular scenery and eponymous whisky brand, but also for unique rock exposures that could resolve some puzzles of Snowball Earth glaciations, extremely severe ice ages in early Earth history. Amazingly, during these events ice sheets could have extended all the way to the equator! Hunting for some baryte minerals at Foss mine near Aberfeldy and visiting the Edinburgh and Glasgow geological museums were equally important to solve the enigma posed by those astonishing glaciations.

I knew that until mid-June I would focus on literature review and preparing rocks already-at-hand to provide context to those I would later collect in the field. Indeed, for almost 2 weeks I have mainly cut rocks originally collected 40 years ago and then (to my surprise and initial scepticism) scanned their polished surface with an ordinary office scanner.

Rocks are very simmilar to books: you can “read” them, and “scan” with ordinary office scanner! One can alos create a small “puddle” of water on the scanner surface to get the best results.

Good news: such notorious 9-to-5 (10-to-6 to be precise) lifestyle CAN tantalise and excite. Some thrill came from the possibility that the diamond saw might cut off my fingers. But so far, so good – thanks to extensive health and safety induction in the rock preparation laboratory (although I do need to keep reminding myself not to accidentally stare at the scanning light when the protruding rock surfaces prop-open the scanner cover).

Diamond saw for cutting rocks in action (photo taken during the rock-cutting “tutorial” delivered by my supervisor, Dr Tim Raub). This wonder apparatus is found in the rock cutting/grinding/polishing laboratory in the basement of Irvine building

I started to enjoy my cutting/grinding adventures even more when I realized how unique those samples are. These rocks are called stromatolites, created when microbial communities precipitate calcium carbonate layers and bind trapped particles of clay and silt inside of sticky polymeric secretions. Such microbial activity creates spectacular bands of alternating pale-dark material.

Two scans of the polished surface of the stromatolite samples. The dark material is mainly clay and silt. The pale layers are calcium carbonate precipitated by bacteria. This spectacular banding can be analysed statistically using specialised software.

From 720 to 635 million years ago during the aptly-named “Cryogenian” Period (the timespan including most Snowball Earth events), and before macroscopic animals had evolved, stromatolites were ubiquitous within mid-to-low-latitude coastal and seafloor sediments. In contrast, modern stromatolites are very rare, mostly known from East African rift lakes, some parts of the Bahamas reef, and in very salty Shark’s Bay in Western Australia.

Some of the stromatolites I am working with are actually from Australian Shark’s Bay.  Others are older Australian rocks associated with Cryogenian climate changes.  Crucially, it might be difficult to initiate such a study using new samples, as Australia restricts stromatolite collection and export for conservation reasons, much like dinosaur bones or human artifacts.

When these rocks were collected in 1977, no one realized that these ancient rocks are finely-tuned clocks and can give invaluable insight into the conundrum of Cryogenian glaciations. The internal banding patterns and shapes of stromatolites can provide unmatched information on the changes in the Sun-Earth-Moon system, which, in turn, can reveal causes, character, and timing of shifts in Earth’s climate from one extreme to another.

Therefore, these stromatolites are indeed a very valuable contribution to the project goals, and I’m eager to explore them statistically, before progressing on to the field part of my project. And actually, this Thursday, I broke away from St Andrews to visit Foss Baryte Mine. Although it was such a great time-off in the picturesque Scottish Highlands, going into much detail would require another few hundred words.

Instead, I would just say that I am so grateful for this chance to do something useful this summer, and to use all the difficulties of the research project and leadership training events to become a brighter researcher, a more confident leader, and to enjoy my life in all its varieties. And since the variety is the spice of life, I wish all interns to work hard on their projects, but also sometimes escape from the reclusion in the archives and find inspiration for the new bright ideas in that thought-provoking summer air!

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