evidence: Laying geological groundwork for life on Earth [...] New research analyzing pieces of the most ancient rocks on the planet adds some of the sharpest evidence yet that Earth’s crust was pushing and pulling in a manner similar to modern plate tectonics at least 3.25 billion years ago. The study also provides the earliest proof of when the planet’s magnetic north and south poles swapped places. The two results offer clues into how such geological changes may have resulted in an environment more conducive to the development of life on the planet. The work, described in PNAS and led by Harvard geologists Alec Brenner and Roger Fu, focused on a portion of the Pilbara Craton in Western Australia, one of the oldest and most stable pieces of the Earth’s crust. Using novel techniques and equipment, the researchers show that some of the Earth’s earliest surface was moving at a rate of 6.1 centimeters per year and 0.55 degrees every million years.