Welcome to the Late Precambrian, an era of dramatic geological change and the beginning of New England’s story. At this point, the earth was 3.5 billion years old. It had already experienced multiple episodes of continental drift, volcanism, and glaciation. The Grenville Mountain chain, formed during an earlier period of tectonic collision, had eroded. All that remained was a small layer of bedrock and a large amount of sediment that would eventually become western Massachusetts. Three major continents contained most of the planet’s land mass: Laurentia, Baltica, and the supercontinent Gondwana, whose coastline roiled with volcanic activity. The earthquakes and lava flows were symptoms of tectonic subduction (when one tectonic plate dives beneath another) and rifting (when two plates diverge). Over time, these subterranean stirrings formed the Avalon mountain range and Boston Rift Basin off the coast of present-day South America. We now call this region New England.