In Cambridge, someone has cut down all the trees outside of the Knight office on Main Street, and chipped them into slaw. Sawdust, light brown and faintly sticky, now joins the slurry of black cardust coating the thawing banks. If you’re having a bad day, it helps to not look. One can’t help but long for the purity of clean landscapes: the square jaw of a cliff edge against blue sky, or the elegant twist of a sand dune along an ocean shore.
Fortunately, some of these things exist in the Siderian, the dawn of the Proterozoic, the longest and leanest eon of Earth’s history beginning 2.5 billion years ago. Hooray for the imagination, time machine extraordinaire.
Today I spoke with Andrew Knoll, a paleontologist and geobiologist at Harvard who has a wondrous mental time machine and is something of a specialist on the Proterozoic. Among other things. He will be walking me through a few key parts of the Proterozoic. Here’s an audio taste from today, just roughly edited together this afternoon:
So when the Earth is 2 billion years old (2.5 billion years ago), it has the makings of continental shelves. Sediments sliding off continents into the sea. Plate tectonics. Oxygen is still not widely prevalent in the atmosphere or the ancient seas, which are full of iron dissolved throughout. But much of that is about to change; it ain't called the Siderian for nothing!