Behind the scenes: Aarno Kotilainen, marine geologist, GTK

A small blond boy ran down to the beach as soon as he got his eyes open. The beach was in his opinion the most wonderful place in the world. It was so lovely to jump in the cool water. And just as great it was to sit on the beach and dig golden, soft sand from the bottom, and to look how sand (grains) flowed from his palm back to the water. That little boy wouldn’t have guessed, that 50 years later the same “boy”, with less hair, digs sand and mud from the seabed equally enthusiastic, and even gets a living from it.

I am that small blond boy. My name is Aarno Kotilainen. My friends call me Ale. I am a marine geologist and work as a research professor at the Geological Survey of Finland, in Marine Geology unit. I studied geology at the University of Helsinki, and did my PhD thesis ”Late Pliocene and Pleistocene sedimentation in the North Pacific Ocean” at the University of Cambridge, England.

The geological expeditions have taken me to magnificent and interesting landscapes around the world, like to the Weddell Sea in Antarctica and the Pacific Ocean, and around the Baltic Sea. With the SEAmBOTH project, I have been given a wonderful opportunity to explore the northernmost underwater landscapes of the Baltic Sea.

Outi Hyttinen and me onboard the drilling vessel Greatship Manisha during the IODP Expedition 347 Baltic Sea Paleoenvironment, 12 September-1 November 2013. Photo: ©ECORD_IODP.

At present my research interests include paleo-oceanography, sedimentology, stratigraphy, marine geological habitat mapping, and sedimentation processes.

Methods are the key element in the marine geological mapping and research, as getting information from the seabed is a bit trickier than on dry land. Over the years, development of the methods has been dizzying. When I started my own career in marine geology, positioning at sea was made in some places with sextant. Today, satellite positioning is available to everyone. Similarly, the different acoustic-seismic sounding methods have evolved rapidly. Currently widely used modern equipment like multibeam echosounder, sediment echosounder, side-scan sonar and seismic sounding have been used also in the SEAmBOTH project to survey seabed in the SEAmBOTH areas of the Bothnian Sea.

Positioning with sextant onboard the research vessel Geola in the late 1980’s. Photo: GTK.

We marine geologists provide SEAmBOTH information e.g. on bathymetry, seabed geomorphology and seabed substrates. In addition to that we study also sediment archives, i.e. geologic records. Particularly those muddy, organic-rich sediments that have accumulated nearly continuously on the seabed, provide unique information on past environmental changes.

The Kastenlot core 211660-6 from the Gotland Deep, showing nicely laminated sediments that were accumulated during the Medieval Climate Anomaly around 1000 years ago. Photo: GTK.

Multidisciplinary cooperation is crucial for providing reliable and sufficient information about the marine environment. In the SEAmBOTH project we have biologists, geologists, geographers and modellers from Finland and Sweden working together. In my opinion, that interdisciplinary cooperation is good fun and more over – also very educational.

Me happily washing a nice GEMAX sediment core onboard the research vessel Geomari. That sediment core was recovered from the SEAmBOTH study area in summer 2019. Photo: GTK.

Winter is dark and long, but the expectation of the next summer will give us strength to endure over the dark winter. I am already looking forward to seeing, smelling and feeling the seabed mud and sand again. And not forgetting ”Huuhkajat” and the UEFA Euro 2020 final tournament.   

Waiting for next summer and more mud. Photo: GTK.

Aarno Kotilainen, GTK

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