Plate tectonics started at least 3.5 billion years ago
by Carolyn Gramling
3:12pm, September 21, 2017
ROCK OF AGES Plate tectonics may have started as early as 3.5 billion years ago on Earth. That recycling of Earth’s surface leads to the separation of light-colored continental crust (exposed here at Yosemite National Park’s Half Dome) from darker, denser oceanic crust.
Plate tectonics may have gotten a pretty early start in Earth’s history. Most estimates put the onset of when the large plates that make up the planet’s outer crust began shifting at around 3 billion years ago. But a new study in the Sept. 22 Science that analyzes titanium in continental rocks asserts that plate tectonics began 500 million years earlier.
https://www.sciencenews.org/blog/science-ticker/plate-tectonics-started-least-35-billion-years-ago
