Nation & World News

Researchers Find Ancient Seawater Had Twice The Salt

By Scott Neuman on November 20th, 2013

Scientists have discovered a pocket of ancient seawater that’s been trapped underground near the mouth of the Chesapeake Bay since the time of the dinosaurs — strong evidence that the Atlantic Ocean was once much saltier than today.

A team headed by Ward Sanford, a hydrologist from the United States Geological Survey, found the 100- to 150-million-year-old seawater deposited between layers of sediment deep under present-day Cape Charles, Va. They detail their findings in the most recent issue of Nature.

Sanford tells NPR that the impact of a large asteroid or comet some 35 million years ago, which has long been known, helped isolate the water, preventing it from being flushed out of the sediments.

The USGS team found the early Cretaceous-era seawater 5,000 feet down as it was drilling in an effort to map a freshwater aquifer. What it found was a watery fossil — the oldest large body of seawater yet identified.

“When we actually drilled and took the core back, we found that there was a large section of the core that had water in it that had about twice the salinity of modern seawater,” Sanford tells NPR. (The Dead Sea, for comparison, is nearly 10 times as salty as the present-day oceans.)

The seawater wasn’t found in one large pool, but trapped in small pores and rock fractures — so there’s no Cretaceous-era life swimming about in it, Sanford says. Still, there is a lot of it: about 3 trillion gallons — or one-sixth the volume of the modern Chesapeake Bay — he estimates.

When the water was trapped 100 million or more years ago, “the Atlantic was a smaller ocean,” he says.

“It had only been in existence [at that time] for about 50 million years and it was isolated from the rest of the world’s oceans,” he says. “It had its own salinity and its salinity was changing at a different rate and by different amounts from the rest of the global oceans.”

How did they know that what they were looking at was indeed ancient seawater?

Sanford explains that first, seawater has a chemical fingerprint. Second, uranium in sediments gives off helium as it decays, and this water had a “very, very high” concentration of dissolved helium.

“If you can measure the amount of helium in the water, that can tell you how long the water’s been sitting in the ground,” Sanford says.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

This entry was posted in News from NPR. Bookmark the permalink.

Comments are closed.

 

More Stories in News from NPR

Mary Jane Fiesta Veloso (center) of the Philippines, is escorted by Indonesian officers during a hearing to appeal her conviction on drug-smuggling charges in Yogyakarta, Indonesia, in March. Veloso is one of three "Bali Nine" inmates who have been told their execution date is imminent.

Indonesia Sets Executions For 3 ‘Bali Nine’ Drug-Smugglers

At least three members of the trafficking ring — two Australians seen as ringleaders and a Filipina maid who acted as a “mule” — have been informed that their execution by firing squad is imminent.


On Everest, Quake-Triggered Avalanche Leaves Death, Chaos

Early reports are that at least eight climbers and/or their Sherpa porters have been killed at Everest Base Camp. Others are trapped higher up on the world’s tallest peak.


Near Valletta, Malta, on Thursday there was a funeral service for 24 of the hundreds of migrants who died earlier in the week when the ship they were on capsized and sank.

There’s A Sad Reason ‘Migrants,’ Not ‘Immigrants,’ Is The Word Being Used

Hundreds of people died this month when an overloaded ship sank in the Mediterranean Sea. They were on the move, but never reached their destinations.


Volunteers help with rescue work at the site of a building that collapsed after an earthquake in Kathmandu, Nepal, on Saturday. The temblor is the worst in Nepal in 80 years.

More Than 1,000 Confirmed Dead In Nepal After Powerful Earthquake

The powerful temblor hit north of the capital Kathmandu, toppling buildings in the capital. Dozens were also killed people in neighboring India, China and Bangladesh.


From left, Bruce Jenner, Kanye West and Kim Kardashian attend FOX's "The X Factor" Season 2 Top 10 Live Performance Show on Nov. 21, 2012 in Hollywood, California.

Jenner: ‘For All Intents And Purposes, I Am A Woman’

In an interview with Diane Sawyer on ABC’s “20/20″, the former gold-medal-winning Olympic decathlete described a struggle with gender identity that began in childhood.


Thank you for your support

WUFT depends on the support of our community — people like you — to help us continue to provide quality programming to North Central Florida.
Become a Sustainer
I want to support FM 89.1/NPR
I want to support Florida's 5/PBS
Donate a Vehicle
Underwriting Payments