Follow the Duck through Deep Time
If you dropped a rubber duck in the ocean near Antarctica, where would it go?
This is a deep-time cousin of an activity you may already know — tracking a floating object as ocean currents carry it along. Here, we ask a bigger question: would the duck’s journey have been different tens of millions of years ago, before Australia and Antarctica drifted apart?
A note on honesty: the duck’s path is not a real physics-based ocean model — real ocean circulation depends on wind, temperature, saltiness and the shape of every coastline, which is a much bigger calculation than this. What it does honestly is never cross dry land: the route is the real shortest sea-only path between two points, using the real reconstructed land shape at each age — so if the path bends, it’s because real land was actually in the way.
60 million years ago: close together
Australia was still joined to Antarctica along most of what’s now the Tasmanian Gateway. A closed gateway leaves no sea-level route for water — or a duck — to slip straight through, so anything trying to sail east has to go the long way round instead.
Drag the slider and watch the detour shrink
At 60 and 50 Ma the duck barely gets a shorter route at all — the gateway is still effectively closed. By 15 Ma the detour has shrunk a lot, and today the duck can take a nearly straight line past Australia. Real scientists think the opening of gateways like this one — letting water flow all the way around Antarctica — helped the Southern Ocean grow much colder over millions of years, which may have helped kick-start Antarctica’s ice sheets.
Try it yourself
- Between which two ages on the slider does the duck’s route change the most?
- How far out of its way — and in which direction — did the duck have to travel at 60 Ma compared to today?
- Ask a grown-up about the real Antarctic Circumpolar Current and how strong it actually is.