Scientific Progress Goes 'Bonk'?

By Brian Calder

Have you ever seen the "Calvin and Hobbes" cartoon where Calvin builds a duplicator (a cardboard box) and asks Hobbes to push the button to duplicate him?  In just four panels, Bill Watterson manages to capture much of the essence of modern scientific enquiry: scientific ethics, prudence, disputed precedence, experiment, and - crucially - that scientific progress isn't announced by someone in a toga shouting "eureka!" in the street, but, as Hobbes skeptically puts it "Scientific progress goes 'Bonk'?".  I have a framed copy on the wall in my office, and recommend it to all of the students.

We're seeing something similar here in Victoria Fjord, Greenland: there is a marked lack of sediment, and we're not entirely sure why.  Scientific progress here, is starting with "Huh?".

To be clear, I'm not a geologist, although I've worked alongside them for years and have learned just about enough to be dangerous.  But here's the situation: when you have had a glacier growing out into a fjord, you should see lots of sediment left behind as the glacier retreats.  It grinds up and accumulates a lot of sediment as it flows down and into the sea from land, and as the front edge melts back sediment gets washed out.  Huge volumes of sediments are also often deposited by subglacial meltwater during melting and retreat. Sediment should be everywhere, and in the other two fjords (Petermann in 2015, and Sherard Osborn in 2019) it was.

You go looking for sediment, and the record of changing conditions that it captures, initially with a sub-bottom profiling sonar which can image the upper few meters of layered sediments below the ship.  Then, once you've identified a good target remotely, you take a physical sample by coring: you drop a weighted hollow tube (about 12cm diameter, 9 m long and 2000 kg) off the back of the Oden into the seafloor and extract a long, section of sediment, often to many meters depth.  You pull that back up onto the ship, take it out of the liner and then split it so you can preserve part, and make measurements on the other.

But for the last week we've been hunting for sediment, and finding none of note.  Matt O'Regan and his collaborators have even been taking cores every day or so on the most likely targets, and getting very little back for their efforts!  Mostly, there has been a small core returned, and evidence that the corer hit hard till or gravel just below the surface -- in one case even damaging the coring device (it's now repaired and back in business).

Photo credit: Sophie teh Hietbrink

So where's the sediment?  We know that there was a glacier here -- the evidence is all around us -- but either it didn't drop any sediment (which is almost impossible to believe), or that sediment got washed away somehow by a mechanism or mechanisms unknown, and contrary to what happened in Sherard Osborn Fjord, which is literally right next door.  Since the two glaciers have essentially the same source, it's also pretty unlikely that the conditions in the glacier would be so different (in terms of how much sediment they contain), so there must have been sediment at one time.  But then if it was going to be washed away you'd expect that the smaller, finer sediment components would have been washed out more than the coarser sediments, and you'd still see the residuals.  And we haven't, yet.

Photo credit: Jon Persson

It's a bit of a mystery, but that's the essence of scientific investigation: although we know a lot about the world and how it works, there's always something new to learn, and new explanations to find.  It's not always comfortable when you find something new and exciting, and it's often painful when your beautiful theory goes up in a puff of smoke in the face of new evidence.  But the drive to explore, to understand, is at the core of what makes us human, and that's why we keep doing it, even when it means a long time away from our homes and families in a remote part of the world.

As Carl Sagan used to say "Extraordinary claims require extraordinary evidence".  So we better get back to collecting some more evidence -- there's another core scheduled for today, in a nice juicy target we saw on the overnight sonar watch last night.  Keep your fingers crossed; listen for the "bonk" – or if you’re on the back of the ship coring, hopefully not.

**Geology validated by a real marine geologist, thanks Matt!