Eons Ago

Earth May Have Wobbled Long Ago
Associated Press, Jan. 20, 2000

Scientists studying underwater volcanoes have found evidence the Earth may have wobbled like an out-of-balance ball 84 million years ago, relocating the poles and shifting the location of Washington to the tropics. Something - they're not yet sure what - appears to have changed the distribution of weight in the Earth, causing it to begin shifting to get back in balance. "What it appears that happened, was a rapid shift," at 84 million years ago followed by a "slow recovery to where things are today," explained William W. Sager of Texas A&M University. That shift of between 16 degrees and 21 degrees, occurring over two million years or so, was rapid in geological terms, he said. It would have moved Washington, D.C., south to about the latitude now occupied by Cuba and the Hispaniola.

The findings are included in a paper by Sager and Anthony K. P. Koppers of the Scripps Institution of Oceanography, appearing in Thursday's edition of the journal Science. "They are suggesting something quite challenging," commented John Tarduno of the University of Rochester, who said the report will surely generate controversy. "Personally, I think there is a possibility that they have underestimated the errors in producing the data set," added Tarduno, who was not part of the research team. The period the researchers focused on was a time of great changes on Earth, Sager noted, with three supervolcanoes erupting and widespread changes in the plates that make up the surface of the Earth.

When these massive plates meet, one gets pulled beneath the other in a process called subduction. This may help account for the shift in the weight distribution, Sager said. Another potential cause is hotspots producing gigantic volcanic flows. During this period, volcanoes produced three massive plateaus, one around the Kerguelen Islands near Antarctica, another in the region of Java, Indonesia and the third in the Caribbean-Colombian area. Sager and Koppers calculated the shift in the pole by studying seamounts in the Pacific Ocean. Seamounts are ancient volcanoes that rise from the ocean floor but are not tall enough to break the surface and become an island. Researchers can determine when they were formed and analyze their magnetic orientation. When molten rock solidifies its magnetic orientation - indicating the direction of the poles - freezes. By studying that orientation now, and how it varies from seamount to seamount, scientists can calculate shifts in the location of the pole over time.

And what Sager found was a relatively rapid shift of the pole beginning about 84 million years ago and lasting about two million years before starting back. There were no people around at the time, and Sager said that while this change is speedy to a geologist, it would not have been noticed by the dinosaurs who populated the planet then. Indeed, he added, "I'm not sure, if we were living in it now, that we would know if it were occurring because of the time frame."