#337 1911 · Roald Amundsen's South Pole expedition · Explorationredesign-the-moment
Amundsen marked his supply depots sideways to the route, not along it, so a lost party could still walk into one
the problem
A featureless landscape swallows single markers
background
On the Antarctic plateau there are no landmarks: no trees, hills or roads to triangulate against, only white in every direction, frequently erased further by fog and blowing snow. Amundsen's plan for reaching the South Pole depended on a chain of supply depots laid down in advance, each stocked with the food and fuel a five-man party would need on both the outward run and the return — miss one, on a return leg with dwindling rations, and the miss could be fatal.
The obvious way to mark a depot is to put a flag on it, or a line of flags along the route leading to it. But a single point is easy to walk past unseen in poor visibility, and a line of markers running parallel to the direction of travel fails exactly when it matters most: if a sledging party drifts even slightly off its compass bearing in a whiteout, it can pass within a few hundred metres of the depot's own line of flags and see nothing, with no way to know which side of the line it has missed on.
the move
Amundsen marked each depot not with a flag on the spot, but with a row of numbered black-flagged bamboo poles running east and west of it — perpendicular to the north-south line of travel — spaced roughly 900 metres apart and extending about four to five miles out on either side. A party approaching from any point within that wide corridor, even badly off its intended line, would cross the marker row and could then read the numbered poles to tell which direction and how far to travel to reach the depot itself.
the payoff
Amundsen's party located every depot it laid on both the outward and return legs of the roughly 1,860-mile round trip to the Pole and back in 1911–1912, reaching Framheim without a single resupply failure. He recorded the method himself, explaining that markers running along the route "may easily be missed in fog" while a cross-line "cannot be missed" if the party is anywhere near its intended course.
what came after
The depot-flagging system is one of the most frequently cited pieces of Amundsen's planning in polar histories, held up against Robert Falcon Scott's rival, fatal expedition of the same season as an example of designing for the failure mode (getting off course) rather than assuming perfect navigation; it remains a standard illustration in polar-exploration writing of engineering a system to survive the searcher's own error, not just to look for the target.
filed under
references
- [1]The South Pole: An Account of the Norwegian Antarctic Expedition in the 'Fram', 1910–1912Roald Amundsen, via Project Gutenberg, 1912gutenberg.org
- [2]Depot Journeys - Chapter 6, The South Pole by Roald AmundsenCool Antarctica, 2021coolantarctica.com