CLIMATE × EARTH

The Glaciation That Was Not a Snowball

~581 to 580 million years ago

Proterozoic · Neoproterozoic · Ediacaran

Ice reached middle and even low latitudes a third time, and stopped short. In Newfoundland, volcanic ash beds bracket the glacial debris between 580.9 and 579.9 million years ago, and one of the glacial units took at most 340,000 years to accumulate, when a snowball, by the theory that names them, has to last millions. Nor is there any pale carbonate lying over it, the layer that caps the other two.

Why it matters

The first large Ediacaran fossils appear less than ten million years later, which has made this brief cold snap the favourite candidate for whatever set animals going, and, for the same reason, the favourite place to test whether cold snaps set anything going at all. A rival reading dissolves the event altogether: the thirty Ediacaran glacial deposits known worldwide would not be one age but a long glaciation drifting from 580 to 560 million years, as each continent in turn crossed the poles.

Dating & uncertaintyDisputed

Volcanic ash beds bracket the Newfoundland diamictite between 580.90 and 579.88 Ma, and one glacial unit lasted at most 340,000 years, far too short for a snowball. A competing reading assembles the world's thirty Ediacaran glacial deposits into a single ice age drifting from 580 to 560 Ma as continents crossed polar latitudes.

Sources

1. Pu et al. (2016), Geology · Dodging snowballs: geochronology of the Gaskiers glaciation and the first appearance of the Ediacaran biota
2. Fitzgerald et al. (2024), Precambrian Research · The Mall Bay Formation (Ediacaran) and the protracted onset of the Gaskiers glaciation in Newfoundland, Canada
3. Wang et al. (2023), National Science Review · A great late Ediacaran ice age

Earth history as one day

20:55:443 h 4 min before midnight

if Earth’s 4.54 billion years were compressed into a single day