The Younger Dryas Impact Ledger: Visualisation

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View

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Focus

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Requirements met

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Platinum delivered

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THE YOUNGER DRYAS IMPACT LEDGER
a comet, 12,900 years ago, or not
seven markers · nineteen years of testing
one line survived: 82.2 ppt of platinum
and its own discoverers argue against it
five requirements, and no body meets three

Part

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Evidence

fact ⇄ what kind of claim · live

The platinum spike is real: 82.2 ppt, a hundredfold rise

Petaev 2013, GISP2 · the one line neither side disputes

MEASURED

The stadial lasted 1,193 years; aerosols clear in ≤15

GICC05 layer counting · published residence times

MEASURED

Hiawatha, the only candidate crater, is 57.99 ± 0.54 Ma

Kenny 2022, shocked zircon · older than the ice sheet

MEASURED

Zero spherules where 800 per kg were reported

Surovell 2009 at two of Firestone's own sites

REPORTED

Two 2025 papers retracted on 11 February 2026

PLOS ONE · age models and sampling; authors dissented

REPORTED

Deliver the platinum and you owe a ~20 km crater

Collins 2005 from your dials · no such crater exists

MODELLED

The Bayesian model is what makes the layer synchronous

15 of 15 modelled · 3 of 29 by Meltzer's audit

MODELLED

What made the platinum spike is still open

a local iron, an Icelandic eruption · neither shown

READING

View

MEASURED

▶ Nothing here is asserted. The overlap count and all five requirements are recomputed from published numbers every frame.

The clock · how are these sites dated?

Precision required…

Drop any site whose age is less precise than this. The proponents' own published standard is better than 100 years. Melrose's modelled interval is 9,475 years wide, and an interval that broad overlaps almost anything.

95% ranges

Black mat

Site

The body · what would have had to hit us

The dials

Diameter…

The only dial that really matters, and it pulls two ways at once. Energy and platinum delivered both go as the cube of this number; the crater you owe goes as its 0.78 power.

Speed…

From 11 km/s, the escape velocity floor, to 72, a head-on long-period comet. Energy goes as the square, but the platinum does not care how fast it arrives.

Entry angle…

Measured from the horizontal. A shallow entry crosses more air and is likelier to break up high; 45° is the most probable angle for a random impact.

Platinum delivered globally…

The fraction of the impactor that becomes fine dust and settles worldwide rather than staying in the crater and its ejecta. Held at 100%, which is as generous to the hypothesis as physics allows.

Composition

Requirement panel

Labels

Animate the entry

Readout · exact from your dials

Energy

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Outcome

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Burst altitude

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Crater you owe

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Platinum in the ice

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Grass ignited to

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How often

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Sites on the boundary

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What is measured vs modelled here

Measured: every published site age and its uncertainty, the 82.2 ppt platinum peak, the 1,193-year duration from ice-core layer counting, Hiawatha's 57.99 ± 0.54 Ma, and the replication counts on both sides. Reported: the claims and the tests, quoted as the record gives them, including the two 2026 retractions and the authors who dissented from them. Modelled: everything the impactor bench computes, from Collins/Melosh/Marcus 2005 and the published impact flux, plus the arithmetic turning an impactor mass into a concentration in Greenland ice. Reading: what actually made the platinum spike, which is still open.

Where the platinum arithmetic comes from

Take the impactor's mass, multiply by the platinum fraction for its composition, spread it over the whole Earth, and divide by the mass of ice that accumulated at Summit during the twenty-one years the spike lasted. Greenland's accumulation rate at 12.9 ka is 0.086 m of ice equivalent per year. Run the chain backwards from the measured 82.2 ppt and it returns an iron body about 830 m across, against the ~0.8 km Petaev et al. state in the paper that reports the measurement. Nothing was fitted to make that agree. It is the same arithmetic they did, and it is why their own paper says a crater of a few kilometres should exist.

Where this bench takes liberties

The entry drawing is schematic in the horizontal: the altitude axis is true, but the track is compressed so a shallow entry fits the frame. The impactor is drawn log-scaled, or a four-kilometre body would fill the screen. The crater is drawn against a stated 100 km ruler, which is honest but means a Tunguska-scale crater is smaller than a pixel and gets a floor. The atmospheric model is the standard pancake treatment, which its own authors note is calibrated by only two events, Chelyabinsk and Tunguska, and should be applied cautiously far outside that range. And the requirement thresholds are choices: a crater under 300 m might hide, a thousand kilometres of ignition counts as continental. Move them in your head and the conclusion does not move, because the gaps are orders of magnitude wide.

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click any site · switch to the direct dates and watch the boundary come apart