When envisioning Snowball Earth, forget any ideas you’ve got about snow-covered woodland glens, 6 inches of powder pushed off car windshields, or anything at all resembling current-era Earth with a whole bunch of snow dumped on top. The geological time period from 717 to 661 million years ago ended a full 130 million years before the first eel-like vertebrates squirmed through the ocean, 276 million years before the first trees, 428 million years before the first proto-mammals, and about 658 million years before the first humans strode across Africa, as New Scientist outlines. Snowball Earth wasn’t just “Earth, but cold and snowy” — it was an utterly alien planet unrecognizable next to its current form.
In fact, Snowball Earth more or less started at the end of what’s known as Earth’s “boring billion,” a colossal 1-billion-year span of time from about 1.8 billion to 750 million years ago when not much seemed to happen on the surface of the planet. Geological activity was sparse during this period, and volcanic eruptions quiet. As The Conversation describes, Earth’s oceans were mammoth vats of sulphur and iron brewing and simmering with the rudiments of multicellular life. It took this entire period to give rise to a lifeform that would reshape the atmosphere into something recognizable and oxygen-rich: algae. And then, a short 33 million years after the boring billion came to a close, Earth erupted and ignited into the flames of volcanic activity that lasted for 2 million years.