Planetary heartbeat? Earth has a geologic ‘pulse’ every 27.5 million years

NEW YORK — Every living, breathing person has a heartbeat, but does our rocky planet have one too? Researchers from New York University suggest the Earth has a pulse too. Their study finds that geological activity on Earth appears to follow a set 27.5-million-year cycle. Incredibly, scientists analyzed about 260 million years’ worth of major geological events to make this conclusion. During their investigation, study authors noticed recurring clusters of geologic activity roughly every 27.5 million years.

“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,” says lead study author Michael Rampino, a geologist and professor in NYU’s Department of Biology, in a university release.

Over the past 50 years or so, more and more scientists have warmed up to the theory that our planet experiences cycles of major geological events, such volcanic activity and mass land or sea extinctions. However, experts continue to debate the exact timeframe of these cycles. Estimates range from anywhere between 26 million to 36-million-year cycles.

Humans are probably safe from Earth’s next ‘heartbeat’

It isn’t exactly easy to study events that occurred tens of millions of years ago. In fact, technological limitations have largely hampered efforts to properly date geologic events in the past. Luckily, recent years have seen big improvements in radio-isotopic dating techniques as well as changes in the geologic timescale. Consequently, Prof. Rampino and his team were able to put together an updated, more accurate record of major geological events taking place over the last 260 million years or so. After accomplishing that, scientists started a new analysis.

The team assessed the ages of 89 well-dated major geological events taking place over the last quarter-billion years. Examples of such events include major volcanic outpourings of lava known as flood-basalt eruptions, events which depleted the oceans of oxygen, sea-level fluctuations, changes in the Earth’s tectonic plates, and marine or land extinctions.

That analysis led researchers to observe that major global geologic events have pretty much only occurred at 10 distinct points in time over the past 260 million years, with each cluster taking place roughly 27.5 million years apart. The most recent cluster occurred approximately seven million years ago, indicating that humans won’t need to worry about the next pulse of major geological activity for another 20 million years or so.

What’s the cause of these pulses?

Study authors can’t say for sure, but theorize they may be a function of other activity cycles within our planet’s interior. For example, processes linked to plate tectonics and climate. Another theory points to the Earth’s orbit playing a role in the pacing of these clusters.

“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,” Prof. Rampino concludes.

The findings appear in the journal Geoscience Frontiers.

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