The landmass that once became Antarctica was along the equator. In Earth’s history, several supercontinents have split up and come together again like the Backstreet Boys.
Our present seven continents and five oceans are the result of more than 3 billion years of planetary evolution, with tectonic plates crisscrossing on top of the semi-solid mire of the Earth’s core.
But it is a challenge to map the precise movements of those plates during all this time; Existing models are often fragmentary, covering only a few million years, or focusing only on continental or oceanic changes, not both.
Now, for the first time, a group of geologists has provided an easily digestible look at 1 billion years of plate tectonic motion.
Geoscientists at the University of Sydney spent four years reconstructing how landmasses and oceans have changed over the past billion years. As part of a recent study, they animated those changes in the short video below.
The animation shows green continents meandering across oceans, which are shown in white. The Ma at the top of the video is geologically speaking for 1 million – so 1,000 Ma is 1 billion years ago. The different color lines represent different types of boundaries between tectonic plates: Blue-purple lines represent divergent boundaries where plates break apart; red triangles indicate converging boundaries, where plates move together; and gray-green curves show transformation boundaries, where plates slide sideways past each other.
“These plates move at the rate the fingernails grow, but when a billion years are condensed into 40 seconds, a mesmerizing dance is revealed,” said Sabin Zahirovic, a University of Sydney geologist who co-authored the new study. , in a press release.
Building a better model of the plates of the Earth
A map shows what Pangea looked like 200 million years ago, with tectonic plate boundaries in white.
Wikimedia Commons
The Earth formed 4.4 billion years ago and then cooled enough to form a solid crust with individual plates about 1.2 billion years later.
Today, the planet can be imagined as a chocolate truffle – a syrupy center nestled in a hardened shell. The center consists of a 1,800 mile thick semi-solid mantle that encircles a super hot core. The top layer – only about 21 miles thick – is the crust, which is fragmented into tectonic plates that fit together.
These plates surf on top of the mantle and move around as hotter, less dense material rises from deep within the Earth to the crust, and colder, denser material sinks to the core.
Geologists can compile a picture of what plates were hundreds of millions of years ago by analyzing what is called paleomagnetic data. When lava cools at the junction of two tectonic plates, some of the resulting rock contains magnetic minerals that align with the directions of the Earth’s magnetic poles at the time the rock solidified. Even after the plates containing those rocks have moved, researchers can study that magnetic alignment to find out where on the world map those natural magnets existed in the past.
Using both paleomagnetic and current tectonic plate data, the study authors were able to create the most thorough map of any plate’s journey from 1 billion years ago to the present day.
A map of the bottom of the Atlantic Ocean.
NASA Earth Observatory Maps by Joshua Stevens, using data from Sandwell, D. et al. (2014)
Put simply, this complete model will help explain how our home, planet Earth, became habitable for complex creatures, Dietmar Müller, a co-author of the study, said in a press release.
The jigsaw puzzle of the Earth’s continents hasn’t stopped shifting, of course. For example, the Pacific is shrinking year after year. Meanwhile, the Atlantic Ocean is expanding and driving America from Africa and Europe.