Huronian Glaciation

The Huronian glaciation was a severe ice age of the Paleoproterozoic era, spanning roughly 2.4 to 2.1 billion years ago and lasting about 300 million years, with at least three separate glacial episodes recorded in the deposition of the Huronian Supergroup. It coincided with the Great Oxygenation Event, when atmospheric oxygen rose sharply while methane fell, and it is associated with the first major extinction event in Earth's history, which devastated anaerobic microbial life. Whether any of its glacial episodes amounted to a full snowball Earth remains contested, since the glacial deposits are discontinuous and alternate with sediments indicating temperate conditions.