Earth’s tectonic plates started shifting earlier than thoughtDate: 25 April 2020 Tags: Geography & Environment
Scientists examining rocks older than 3 billion years discovered that the Earth's tectonic plates move around today much as they did between 2 and 4 billion years ago. The findings suggest that the continents settled into place and sustained life much earlier than previously thought, and give insights into plate tectonics on other planets.
An enduring question in geology is when Earth's tectonic plates began pushing and pulling in a process that helped the planet evolve and shaped its continents into the ones that exist today. Some researchers theorize it happened around four billion years ago, while others think it was closer to one billion.
The researchers believe this shift is the earliest proof that modern-like plate motion happened between two to four billion years ago. It adds to growing research that tectonic movement occurred on the early Earth.
Plate tectonics is key to the evolution of life and the development of the planet. Today, the Earth's outer shell consists of about 15 rigid blocks of crust. On them sit the planet's continents and oceans.
The movement of these plates shaped the location of the continents. It helped form new ones and it created unique landforms like mountain ranges.
It also exposed new rocks to the atmosphere, which led to chemical reactions that stabilized Earth's surface temperature over billions of years. A stable climate is crucial to the evolution of life.
When the first shifts occurred has long been an issue of considerable debate in geology. Any information that sheds light on it is valuable. The study helps fill in some of the gaps. It also loosely suggests the earliest forms of life developed in a more moderate environment.
For the study, members of the project travelled to Pilbara Craton in Western Australia. A craton is a primordial, thick, and very stable piece of crust. They are usually found in the middle of tectonic plates and are the ancient hearts of the Earth's continents.
The researchers point out they weren't able to rule out a phenomenon called "true polar wander." It can also cause the Earth's surface to shift. Their results lean more towards plate tectonic motion because of the time interval of this geological movement.