Earth History

The Age of the Earth

A look into how Geologists learned how old the Earth is.

While 2018’s hottest geology related topic might be the revelations of flat-earth conspirators, another geology topic often debated between is mainly between geologists and conservative Christians– It’s rare to come across someone who’s both. For this debate, we are interested in just how long we have been here. Some American biblical scholars have created a theory that the Earth’s age is closer to 10,000 years old. An estimate far smaller than the estimates we would even hear during the Renaissance. The issue with a 10,000 year old Earth is substantial and the facts are stacked against it.

So if the Earth isn’t 10,000 years old, exactly how old is it?

The Big Question

The contemporary idea that our Earth is only ten thousand didn’t arise until the I’d twentieth century. Before then, scholars and monastic alike, debated whether the earth could be somewhere from hundreds of thousands to possibly millions of years old. The most contentious opinion was, still, only placing the earth’s age at under 100 million years by the famous physicist, Lord Kelvin (interestingly, Lord Kelvin hypothesized the Earth was originally molten rock and calculated the time it would require to cool down to end up with the Earth’s age somewhere between 20 million and 400 million). These dates, however, didn’t agree with the studies being made by renown biologists Lyell and Darwin, who stated this was nowhere near enough time to agree with their observations on evolution.


It wouldn’t be until the age of radiometric dating of Ernest Rutherford we could finally test these hypothesis. Above all of that, the source material tested in order to best calculate the Earth’s age wasn’t even from this planet, but from a meteorite.

Radiometric Dating

At the heart of it, radiometric dating is calculating just how old an object is by weighing its atoms. When a rock is formed, it contains a specific number of radioactive atoms. These atoms have a specific weight. As the rock ages, the number of atoms with a radioactive mass decreases. By measuring the ratio of atoms at a mass where its radioactive against non-radioactive masses, we can accurately determine how long the rock has existed.

The most common of radio-dating we hear about is Carbon dating. This form of isotope dating is only accurate for samples less than 50 years old. For accurately dating the age of the Earth, Lead and Uranium are the elements we need to focus on. Clair Cameron Patterson used Uranium-lead isotope data from several meteorites to conclude the Earth is around 4. 5 billion years old; far older than any previous calculations. His theory was that the Earth must have been made from the same material as these meteorites and that their creation must have occurred very close to the formation of the Earth as a whole.

peridotite-xenolith
Peridotite. This is a sample of olivine-rich rock that is similar to the composition of meteorites that can help with dating the Earth

Other Evidence

Since then, small samples of zircon have been found in Canada and Australia– these zircon crystals are understood to be some of the earliest mineral formations after the Earth’s creation, predating the creation of the moon. These zircon minerals have been dated to 4. 375 billion years old (give or take a few million), validating the prediction of the Earth being formed when Claus Cameron Patterson had predicted.

oldeast-Zircon
This is the fragment of Zircon analyzed by researchers in Madison, Wisconsin. The mineral has been dated to around 4.375 Billion years old, making it the oldest known mineral on Earth. Interestingly enough, to form a mineral such as this, liquid water may have been involved.

Since his work in the 1950’s, the technology and calculating methods for dating materials has improved in accuracy and precision. Newer estimates place the Earth closer to 4. 6 billion years (not far off from the conclusion of Claus Cameron Patterson).

So although the debate of the Earth’s age is a hot topic for today, the information gathered by geologists make a strong case for an Earth far older than she initially suggests.

 

Being a Jack of all trades and Master of none is a true curse. I find myself diving head first in a new hobby or interest just about every other week. Through my writing and my online projects, I have been trying to hone this thirst for new activities to create something worthwhile. I have a degree in Geology and Environmental Science. I also spend a large amount of my time sketching and animating. To get myself outdoors, I love to play rugby and go hiking.

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