New research suggests that virtually no new mountains were created during the Proterozoic era, halting the evolution of life on Earth for roughly a billion years.
(CN) — More than a billion years ago, tectonic activity on Earth may have stopped so completely that no new mountains could be formed on the planet for an entire eon — putting evolution of life on Earth on pause in the process.
If there is one thing that the scientific record has made quite clear regarding the long and complex history of Earth, it is that our planet has experienced an extraordinary amount of change in the 4.5 billion years that it has existed in our solar system.
What was once a hot, barren wasteland has evolved into the sprawling and complex hub of life we know it to be today, an evolution that took place over the course of numerous ice ages, mass extinction events and periods of extreme geographical adjustments.
But there is one chapter in the history of Earth that is oddly void of these planetary shakeups, a time period that saw virtually no known changes to the planet or its denizens. Experts call it the Boring Billion, an eon of inactivity that is frequently cited as the dullest time in Earth’s history.
While scientists are still looking to learn more about the Boring Billion, new research suggests that there may be a culprit behind this billion-year long planetary slumber: an almost complete shutdown of Earth’s tectonic activity.
In a new study published Thursday in the journal Science, researchers report that the tectonic forces underneath Earth’s surfaces may have stalled so completely that it resulted in no new mountains being formed during the Proterozoic era that took place around 2.5 billion years ago.
The study suggests that with no new mountains being created, it invoked a chemical response that put the evolution of life on Earth hold for nearly a billion years — resulting in what we now call the Boring Billion.
Researchers led by Ming Tang of the Key Laboratory of Orogenic Belt and Crustal Evolution at Peking University in Beijing, China say they made this discovery by taking a close look into the thickness of Earth’s crust throughout history. While the thickness of the crust is constantly in flux and can be difficult to accurately track, experts were able to get a good idea of the history of Earth’s crust after studying anomalies in special minerals known as zircons that eroded from ancient landmasses.
Using data from these ancient minerals, researchers were able to deduce that Earth’s crust lost a good portion of its thickness during the Proterozoic era, a loss directly caused by the gradual erosion of Earth’s mountains. Researchers say that without the tectonic activity needed to create new mountains, time simply chipped away at our mountain supply faster than Earth could replenish it.
With mountain production put on hiatus and Earth’s crust losing its thickness, experts say life on Earth had little choice but to stop evolving. This is because mountain formation is a key player in helping the nutrient cycle on the planet moving in the right direction, supplying crucial natural resources to the land and the oceans for the lifeforms that rely on them. Once that cycle was disrupted, evolution was brought to a standstill and the Boring Billion began.
Researchers report that after about a billion years, tectonic activity eventually kickstarted itself back into business, making the spread of nutrients across Earth’s surface possible once more.
“As mountains reappeared on the continents, nutrient supply to the oceans was enhanced, which catalyzed surges in biological productivity and resumed surface oxidation,” the study states. “Efficient orogenesis appears to have been maintained ever since.”
Researchers are not certain what exactly caused this tectonic shutdown in the first place, but suspect that it ties back to the supercontinent Nuna-Rodina, an ancient landmass that is reported to have formed early on in Earth history.
Scientists say the supercontinent may have changed the thermal structure of the planet’s mantle to such an extent that it disrupted the behaviors of the above crust, forcing tectonic activity to grind to a halt.
Regardless of what ultimately was behind this idling period, researchers stress that these revelations and others like them are starting to fill in some of the major gaps in our knowledge about Earth’s strange — and occasionally dull — formative years.