By taking a look at the timing of historic and colossal geological events over hundreds of millions of years, it’s possible to see cyclical bursts of activity that repeat at a relatively steady pace. Describing this pattern in a new study, scientists at New York University and Carnegie Institution for Science describe this phenomenon as the “pulse of the Earth.” The underlying cause driving this pulse, however, remains a mystery.
As reported in the journal Geoscience Frontiers, the study authors looked at the ages of 89 well-dated major geological events during the last 260 million years, including dramatic changes to Earth's tectonic plates, ocean deoxygenation, major volcanic outpourings of lava, sea-level fluctuations, mass extinction events, and so on.
Their analysis showed these global geologic events were loosely clustered at 10 different time points over the 260 million years, grouped into peaks or “pulses” that repeat roughly every 27.5 million years. According to their workings, the most recent cluster of geological events was approximately 7 million years ago, suggesting it will be another 20 million years before the planet sees another pulse of major geological activity.
"Many geologists believe that geological events are random over time. But our study provides statistical evidence for a common cycle, suggesting that these geologic events are correlated and not random," Michael Rampino, lead study author and geologist at New York University's Department of Biology, said in a statement.
The idea of finding a pattern to Earth’s geological shake-ups is nothing new; ancient religions and belief systems attempted to gauge some idea of vast cycles of events in nature that dwarf a human lifetime. During the past few decades, a number of geologists have put forward the ideas of geological events repeating in a cycle, most of which have gauged a timescale somewhere between 26 million years to 36 million years. Recent improvements in radio-isotopic dating techniques, as well as other scientific developments, have helped researchers refine their datasets and, hopefully, make their estimations increasingly more accurate.
However, it’s still not certain what could be driving this pulse. The study concludes by speculating it might have something to do with internal Earth dynamics affecting global tectonics and climate. Alternatively, the changes may be pushed by the cycles seen in Earth’s orbit of the Solar System and in the wider Galaxy. We might not be sure what's dictating the pulse, but it's clear the peaks of geological activity bring around a colossal amount of change to the fabric of our planet, causing huge upheaval for whatever lifeforms were present at the time.
"Whatever the origins of these cyclical episodes, our findings support the case for a largely periodic, coordinated, and intermittently catastrophic geologic record, which is a departure from the views held by many geologists," explained Rampino.