New study zeros in on plate tectonics' start date: Analysis of trace elements places the onset of plate tectonics about 3 billion years ago

A new study suggests that plate tectonics -- the dynamic processes that formed Earth's mountains, volcanoes and continents -- began about 3 billion years ago. By analyzing trace element ratios that correlate to magnesium content in ancient Earth's crust, the researchers provide first-order geochemical evidence for when plate tectonics first got underway.