Jack Hills Zircon: Evidence of a Very Old Earth

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In a report published in Nature Geoscience, a scientific team studying rocks in Australia, used Australian zircons in the Jack Hills that are embedded in the rocks to decide the age and history of these rocks.

They found evidence that the Earth’s crust first formed at least 4.4 billion years ago.  They analyzed the atoms in zircons and used them like a clock to decide when they were formed.  The clock inside the zircon is the radioactive element uranium, and over time it becomes lead.  Follow this to how zircon is used to date rocks.

Figure 1. 4.4 billion-year-old zircon crystal which is used to determine the age of the Earth.  Credit: John W. Valley/University of Wisconsin-Madison.

Figure 1. 4.4 billion-year-old zircon crystal which is used to determine the age of the Earth. Credit: John W. Valley/University of Wisconsin-Madison.

Zircon, a silicate mineral, is like a buried clock that has ticked from the time it formed or crystallized in molten magma.  Zircon crystals are tiny, but very resistant to geological process, including erosion and metamorphism.  Zircons can survive these processes, and the clock keeps ticking.

According to the researchers:

The Earth was assembled from a lot of heterogeneous material from the solar system,” Valley explains, noting that the early Earth experienced intense bombardment by meteors, including a collision with a Mars-sized object about 4.5 billion years ago “that formed our moon, and melted and homogenized the Earth. Our samples formed after the magma oceans cooled and prove that these events were very early.

Figure 2.  Time Line for a Very Old Earth showing the relationship of the Australian Jack Hills Zircon and the geological timeline of Earth. Photo: Andree Valley/University of Wisonsin-Madison.

Figure 2. Time Line for a Very Old Earth showing the relationship of the Australian Jack Hills Zircon and the geological timeline of Earth. Photo: Andree Valley/University of Wisonsin-Madison.

Although zircons were not mentioned in the recent Bill Nye and Ken Ham Debate on evolution, this research study surely adds to Bill Nye’s idea that the record in layers of rocks, ice cores, tree rings, and fossils provides evidence that the earth is very old.  On the other hand, Ken Ham would dispute the findings in the research study on Australian zircons because this is historical science, and we were not there to see this.

According to the researchers, the zircon data “confirms their view of how the Earth cooled very early“, and became habitable, pushing back even further when life began on earth.

Whether we like or not, the debate on the age of the Earth still goes on.  Nye’s ideas are supported, while Ham will continue to resist agreeing with the findings because his ideology is so strong that he will hold on to his “young earth conception.”

What are your views on the value of the Jack Hills’ zircon findings in discussions of the age of the Earth?

 

 

About Jack Hassard

Jack Hassard is a writer, a former high school teacher, and Professor Emeritus of Science Education, Georgia State University.

…and I’M STILL FOR HER.

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