Early Water on Earth

Geotimes ^ | February 2003 | Salma Monani

[CalConservative]

Isotope geochemistry
Early water on Earth

Geologists have long thought that Earth’s first 500 million years were as hot as Hades, dubbing this time frame the Hadean. The high temperatures would have prevented liquid water from condensing on the surface. But new findings on zircon grains, Earth’s oldest known terrestrial materials, suggest that the Hadean might have hosted liquid water.

Recovered from the metamorphosed sediments of the Jack Hills in western Australia, the zircon grains are dated to be more than 4 billion years old and are the only geological evidence available to provide insight into the first 500 million years of Earth’s history.

“This period is also considered the dark ages of the Earth because there are no known rocks that have been preserved,” says John Valley from the University of Wisconsin-Madison, lead investigator in the Jack Hills zircon research. Presenting at the Geological Society of America’s annual meeting in Denver last October, Valley and his colleagues suggest geochemical clues in the zircons provide the surprising news that early Earth was cool enough for liquid water to exist.

Eranondoo Hill in the Jack Hills of western Australia contains zircon grains as old as 4.4 billion years. A team led by John Valley of the University of Wisconsin-Madison (left) found surprising clues in the grains. Also pictured are Aaron Cavosie of the University of Wisconsin-Madison and Simon Wilde of Curtin University. Photo by David Valley.

In the late 1990s, Valley and his co-workers realized that zircons accurately preserve their original oxygen isotope values, and they decided to document zircons through all of geological time. This realization prompted their discovery of the oldest Jack Hills zircon, a 4.4-billion-year-old detrital grain. The Hadean hypothesis holds that Earth had not yet developed any source materials other than molten magma generated from the interior or from a meteorite bombardment. When the team first placed the grain on the ion microprobe, they expected it to have oxygen isotope ratios of a zircon crystallized in a rock that would in turn have mantle geochemical signatures. But the values of the grain’s oxygen isotopes were much higher than they expected.

“Rocks that have zircons with higher oxygen isotope values indicate a source that has interacted with water at low temperatures,” says Aaron Cavosie, also from the University of Wisconsin-Madison. The new isotope values have two implications, Cavosie says. First, they suggest that water existed as early as 4.4 billion years ago. Because water is a prerequisite for life, this research potentially pushes back the time that life could have originated. Prior to this research, the first known rock evidence for water on Earth was from the Isua metasediments in Greenland, which date to 3.8 billion years ago (Geotimes, July 2002).

Second, the data suggest that the zircons formed in a source rock that was contaminated with material that had interacted with water at low temperatures — that is, rock close to the surface. The trace element geochemistry and quartz inclusions of the zircons corroborate the oxygen isotope data, and point to an evolved rock, much like a granite, indicating that continental crust probably existed on early Earth.

“These are the first real data that suggest that there was supracrustal material that early on Earth,” says co-author William Peck of Colgate University. “In addition, the possibility of liquid water — and perhaps oceans — this early in the planet’s formation is really exciting. It has implications for when catastrophic bombardment of the Earth by meteorites likely waned.” Meteorite bombardments are heat sources, so the idea that early Earth was cool enough for water raises questions regarding the timing and intensity of bombardments.

Alex Halliday, a geochemist from the Institute of Isotope Geology and Mineral Resources in Zurich, suggests caution about the findings. “They are not being outrageous or even factually incorrect. It is just that there are inevitable, fundamental assumptions involved in scaling up a portion of a single grain of zircon to the existence of continents and oceans.”

Valley and his colleagues agree. “The cool early Earth hypothesis is controversial, and we are working very hard to test it,” Valley says. Whereas in 2001 they had only one zircon older than 4.3 billion years, they now have several, which they are using to test their interpretations.

The Jack Hills zircons are proving to be a treasure trove for understanding early Earth. “The most important aspect is that we now have an archive to work on, albeit limited,” Halliday says. “The past 10 years have seen major revisions in our understanding of the earliest Earth, and this field has been viewed as one of the most interesting and rewarding today in terms of significant discoveries.”

Salma Monani
Geotimes contributing writer

[CalConservative]

Aside from the radioisotope dating issues in zircons, a cool earth with surface water present shortly after its formation certainly presents some challenges to standard scenarios concerning the development of the earth and the formation of life.

[MissAmericanPie]

According to Genesis, from the time of Adam to the time of Noah, it had never rained on the earth. Plants were watered from a mist that rose from the ground. Most likely it would be wise for Scientists to start from that assumption.

[coloradan]

How are the theories regarding the formation of life challenged by pushing back the time of liquid water? Life is believed to have evolved in liquid water anyway. Whether the Earth was covered in water or steam before this time makes no difference from an evolutionary standpoint.

[John H K]

According to Genesis, from the time of Adam to the time of Noah, it had never rained on the earth. Plants were watered from a mist that rose from the ground. Most likely it would be wise for Scientists to start from that assumption.

If they'd consumed about 5 tons of crack per scientist, yes.

[John H K]

How are the theories regarding the formation of life challenged by pushing back the time of liquid water? Life is believed to have evolved in liquid water anyway. Whether the Earth was covered in water or steam before this time makes no difference from an evolutionary standpoint.

Eh, you've got to understand the creationidiot mindset. Every time there's some study where someone theorizes species X evolved from Y instead of X evolving from Z, or species X was on earth Z millions of years earlier than previously thought, or something about the early earth geologically may have been different than thought, they have these wild fantasies that somehow all science is totally undermined and evolution is on its last legs.

The problem is they don't get science, at all. The idea of tens of thousands of really intelligent people OUT IN THE FIELD actually digging things up, studying them, debating them, etc. is totally alien to their mindset....and the idea that you can have an overarching theory and have the details modified or changed every once in a while by new data, WITHOUT undermining the overarching theory, is totally incomprehensible to them.

[Abcdefg]

That's a lot of crack, even for a scientist!

[Cvengr]

the idea that you can have an overarching theory and have the details modified or changed every once in a while by new data, WITHOUT undermining the overarching theory, is totally incomprehensible to them.

Whereas in 2001 they had only one zircon older than 4.3 billion years, they now have several

“The past 10 years have seen major revisions in our understanding of the earliest Earth, and this field has been viewed as one of the most interesting and rewarding today in terms of significant discoveries.”

Considering that metallurgists and crystallographers still don't have a universally accepted mechanism for creep, rheological fatigue, and elastic behavior for more than a handful of elements and perfect or near perfect crystal structures, the leap to conclude that any elemental or isotopic absence is evidence proving the age of rock to be 'billions' of years old is just a tad premature.

I agree that this is an interesting find and probably may be used to relationally sort newer from older specimens, but the leap to label these specimens as millions or even billions of years old exhibits the same sort of leap to conclusions which beg the question throughout 'evolutionist' literature.

Perhaps if the same 'evolutionist' shared the same zeal to correlate information with Scripture, they might actually discover far more revealing science.

[onedoug]

Tellers of the some of the earliest creation stories lived near rivers and/or well irrigated regions so that such assertions need not seem so outlandish.

The key would seem an atmosphere that was, and is yet able to retain water, principally outgassed from the earth's interior through volcanism.

These ideas are perfectly consistent with Genesis.

[LiteKeeper]

read later

[Salman]

According to Genesis, from the time of Adam to the time of Noah, it had never rained on the earth.

Where in Genesis does it say it never rained before Noah?

This is part of the creationist geological theory of George Macreedy Price, popular with modern creationists but not the same as Genesis.

[Citizen Tom Paine]

Its been a long time since I had geochemistry, but I thought there was quite a bit of evidence that the Earth formed from cold concretion. That is, cold pieces of material in orbit around the sun were drawn together by gravity. The Earth later may have heated up from radioactive decay of short lived radioactive elements.

[azhenfud]

Genesis Chapter 2
5 And every plant of the field before it was in the earth, and every herb of the field before it grew: for the LORD God had not caused it to rain upon the earth, and there was not a man to till the ground.
6 But there went up a mist from the earth, and watered the whole face of the ground.

[Salman]

Genesis Chapter 2:5 ff.
And every plant of the field before it was in the earth, and every herb of the field before it grew: for the LORD God had not caused it to rain upon the earth, and there was not a man to till the ground. But there went up a mist from the earth, and watered the whole face of the ground.

And when there was a man to till the ground? Adam to Noah, that is?

[azhenfud]

Genesis Chapter Nine
12 And God said, This is the token of the covenant which I make between me and you and every living creature that is with you, for perpetual generations:
13 I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth.
14 And it shall come to pass, when I bring a cloud over the earth, that the bow shall be seen in the cloud:
15 And I will remember my covenant, which is between me and you and every living creature of all flesh; and the waters shall no more become a flood to destroy all flesh.
16 And the bow shall be in the cloud; and I will look upon it, that I may remember the everlasting covenant between God and every living creature of all flesh that is upon the earth.
17 And God said unto Noah, This is the token of the covenant, which I have established between me and all flesh that is upon the earth.

The essence of thought is "no cloud - no rain, no cloud - no bow". A very plausible conjecture, unless sunlight had been so diffused prior to the flood that no bow could form (which that scenario would not make as much sense given the vegetation coverage on the earth). Even in a greenhouse, one can form a "bow" by spraying water into the air.

Have you ever heard of the hydrogen theory?

[azhenfud]

Genesis Chapter Nine
12 And God said, This is the token of the covenant which I make between me and you and every living creature that is with you, for perpetual generations:
13 I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth.
14 And it shall come to pass, when I bring a cloud over the earth, that the bow shall be seen in the cloud:
15 And I will remember my covenant, which is between me and you and every living creature of all flesh; and the waters shall no more become a flood to destroy all flesh.
16 And the bow shall be in the cloud; and I will look upon it, that I may remember the everlasting covenant between God and every living creature of all flesh that is upon the earth.
17 And God said unto Noah, This is the token of the covenant, which I have established between me and all flesh that is upon the earth.

The essence of thought is "no cloud - no rain, no cloud - no bow". A very plausible conjecture, unless sunlight had been so diffused prior to the flood that no bow could form (which that scenario would not make as much sense given the vegetation coverage on the earth). Even in a greenhouse, one can form a "bow" by spraying water into the air.

Have you ever heard of the hydrogen theory?

[blam]

"Aside from the radioisotope dating issues in zircons, a cool earth with surface water present shortly after its formation certainly presents some challenges to standard scenarios concerning the development of the earth and the formation of life."

Yup. Expect in the next few years to read that life on earth is older than ever believed. Good article, thanks.

[Khurkris]

So...this moves the origin dates for beer even FARTHER back. I suspected as much.

[azhenfud]

I guess one should question those expiration dates more seriously, right?

[John Valentine]

I'm aiming my comment to you because, unlike so many other posters here, you do not seem to accept as given that the definitive account of the evolution of the earth is contained in Genesis.

On the other hand, you seem open to different but considered ideas, and so, I heartily recommend to you, "The Hot Deep Biosphere" by Thomas Gold. Gold is the discoverer of Pulsars, among other things, and is Professor Emiritus of Physics at Cornell University. Gold's recent book is fascinating at the very least, and if Gold is correct in his interpretation of the data, revolutionary. According to Gold, the Earth was never all that hot. If you tnink about it, if is the Earth really were "hot as Hades" that extreme heat would have driven away all the water as well as most other lighter elements and compounds. Today's Earth would be a barren ball of stone with just a wisp of an atmosphere and not much else.

If you don't have the $15 to buy the book, you can do a Google search on Thomas Gold and you will find plenty of written material on the web.

I'd be very interested to hear his take on these zircons.

[ALS]

You mean the evoloonist mindset. Myopic ends to a means.