Earth’s Age- How We Know Earth is 4.55 Billion Years Old | GEO GIRL

How did we date Earth? How do we know Earth is billions of years old? How did we date Earth before we discovered radioactive isotopes? In this video, I answer all of these questions, starting with the concepts of relative dating and absolute dating, then we go over the early estimates of Earth's age made before we discovered radiometirc dating, then we discuss the discovery of radioactivity and the invention of radiometric dating, and finally we discuss which types of rocks we use to date Earth and why these methods are so accurate. I also briefly touch on the difference between dating Earth and dating the universe because I often get asked how we can date the universe with light but not Earth... spoiler: it's because we are on Earth, so we cannot measure the time it takes for Earth's light to reach us like we can for planets and stars far away from us in space. Anyway, I hope you enjoy the video!
References: Earth System History Textbook: amzn.to/3v1Iy0G
Exploring Geology Textbook: amzn.to/3AM4CC7
Lord Kelvin and the Age of the Earth by Burchfield, 1990: amzn.to/3gwrX40
John Perry's neglected critique of Kelvin's age for the Earth: A missed opportunity in geodynamics by England et al., 2007: doi:10.1130/GSAT01701A.1.
The Age of the Earth by Dalrymple, 1994: amzn.to/3gAAfYx
Age of meteorites and the earth by Patterson, 1956: doi:10.1016/0016-7037(56)90036-9.
Age of Earth: en.wikipedia.org/wiki/Age_of_...
GEO GIRL Website: www.geogirlscience.com/ (visit my website to see all my courses, shop merch, learn more about me, and donate to support the channel if you'd like!)
Studying for an exam? Schedule Tutoring with me: GEOGIRLTutoring.as.me/
Hey there, Earth enthusiast! Check my favorite Earth-friendly products:
Bamboo toilet paper: shrsl.com/3cvku
Bamboo paper towels: shrsl.com/3cvkw
Compostable tableware: shrsl.com/3cvkz
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(Just click link, press get started, take the free C footprint quiz, then choose how much you want to reduce your footprint by donating to the C sequestration projects they're funding!)
Non-textbook books I recommend:
Oxygen by D. Canfield: amzn.to/3gffbCL
Brief history of Earth by A. Knoll: amzn.to/3w3hC1I
Life on young planet by A. Knoll: amzn.to/2RBMpny
Some assembly required by N. Shubin: amzn.to/3w1Ezm2
Your inner fish by N. Shubin: amzn.to/3cpw3Wb
Oxygen by N. Lane: amzn.to/3z4FgwZ
Alien Oceans by K. Hand: amzn.to/3clMx1l
Life's Engines: amzn.to/3w1Nhke
Tools I use as a geologist/teacher/student:
Geology field notebook: amzn.to/3lb6dJf
Geology rock hammer: amzn.to/3DZw8MA
Geological compass: amzn.to/3hfbdLu
Geological hand lens: amzn.to/3jXysM5
Camera: amzn.to/3l6fGRT
Carbon-neutral pencil bag: shrsl.com/3cvjv
Carbon-neutral backpack: shrsl.com/3cvkc
0:00 Video Outline
1:24 What is Absolute Dating?
3:54 What is a Radioactive Isotope?
6:27 How we use Half Lives to Date Rocks
10:29? How the Geologic Timescale was made
12:03? Early Estimates of Earth’s Age
16:46? After Radioactive Decay Discovery
20:28 Oldest Rocks on Earth
21:53 How we Know Earth is 4.5 Ga
24:06 How the Universe was Dated
24:58 Earth History Confirms Earth’s Age
25:45 Related Videos & References
Disclaimer: Links included in this description might be affiliate links. If you purchase a product or service with the links that I provide I may receive a small commission, but there is no additional charge to you! Thank you for supporting my channel so I can continue to provide you with free content each week! And as always, let me know your topic suggestions in the comments down below!

[@captaincodpiece3263]

I dated the Earth once, it didn’t work out, I think it was the age difference

[@rockets4kids]

Ok dad, you win this one.

[@GEOGIRL]

Hahaha omg you both are hilarious, I am going to pin this comment 😂

[@nicholasmaude6906]

So Earth's a craddle-snatcher😉😁🤣?

[@erictaylor5462]

You need to be careful about dating a planet. Make sure you don't get smushed. kzbin.info/www/bejne/r2PPgmRuoaqMh9E

[@legendre007]

Dating the Rock is very interesting. Not many people know that a wrestler-turned-actor can be such a romantic softie!

[@OzGeologyOfficial]

I get so many comments regarding the dating of the Earth on my videos. With almost all of them being hostile hahaha. So I understood exactly why you added a very clear disclaimer at the beginning. I wouldn't be surprised if you still get a few 😂

[@GEOGIRL]

Hahaha I know right! I got a lot of comments saying that they thought I gave the disclaimer because I live in America, but it was really just because I know how ruthless commenters on youtube can be lol!

[@oldionus]

Especially clear and comprehensible presentation. We need more popular education in Geological sciences.

[@GEOGIRL]

Wow thank you so much! And I agree completely that we should have more geo education out there! ;D

[@peterbreis5407]

@@GEOGIRL I think we should have more education full stop. :)

[@Mjr._Kong]

@@GEOGIRL Have you considered developing a "dating app"? I'll show myself out....🤪

[@andywomack3414]

"Dating a rock is a lot less complicated than dating a human" -undergrad geology student joke. Relative dating has it's own issues.

[@GEOGIRL]

Hahaha so true!

[@justmenotyou3151]

If you think relative dating has its problems(also in most places it is illegal) try dating via zoom.

[@spindoctor6385]

I would like to congratulate Geo-girl for reaching a big enough audience that the telegram scammers are now unleashing the bots into her comment section. This has to be a milestone of significance for any youtuber.

[@BackYardScience2000]

The first minute of this video is exactly how everyone should feel. Period.

[@christianhunt7382]

Geo Girl Rocks! 😁

[@TheRexisFern]

If you're going to date Earth, make sure you take her somewhere very nice. She's been busting ass trying to keep us alive, she deserves the best.

[@Enkaptaton]

As an european the humble introduction made me first puzzle, than lmfao

[@GEOGIRL]

Yea, things aren't so simple here hahaha

[@cedarwaxwing3509]

You don’t plan to add an introductory paragraph to your PhD dissertation explaining that you don’t intend to offend young earth creationists, do you? You are a scientist, and your wonderful geological videos are based on what we know from several hundred years of geological, physics, thermodynamics, chemistry, and biological research. We have not yet sunk to the level of having to apologize to religious believers and science deniers whenever we present research findings. I am a (retired) geologist. I find your videos a tremendous resource for both reviews into areas I am rusty on and for the education of those who have no or little formal training in geology, which in my mind is the most integrative field of science. I do have to tell you that I was shocked and a little disappointed that you started this one with essentially an apology to the ignorant for telling the truth and presenting current knowledge. I think you are setting a dangerous precedent. Presenting real science is always going to generate a certain amount of negative comments from certain groups. You will never satisfy them by adding disclaimers to your excellent explanations.

[@John_Weiss]

I think we in the sciences need to start making it clear that we *_are not_* telling people that "their religion is wrong," we are telling them that "their _preacher's_ dicey, muttonheaded interpretation of scripture *_is wrong_* and needs to adjust to new knowledge. I am a physicist by training, and one of the most popular T-shirts you'll see on physics majors consists of the following 6 lines: "And G*d Said:" _

[@rokualvin6428]

Sir, this is not a PhD thesis, it is a KZbin video, and I have run into the looney tune crowd on my own channel when I stated that Earth was far older than 6,000 years and there was no Noah's flood. I found it refreshing to see Geo Girl just sweep that problem aside so she could move forward. KZbin is not a college campus; it is communication conduit to everywhere in its own way. There is no shame in treating the science deficient people with the same respect as you would treat anyone else. You will never erase them, which means you have to live along side of them. Kudos to Geo Girl for doing that. Now if she altered the science to appease those with no understanding, that would be different. But she did not do that. So, I think your criticism is unfounded.

[@cedarwaxwing3509]

@@rokualvin6428 Well, I disagree with you, and reading through the other comments, I think a lot of people were also dismayed that she began with that disclaimer. A big problem is that it puts her on a slippery slope. Since geology is a science that requires billions or at least millions of years for its processes to work, she’d have put a disclaimer in every video she makes. Science owes no one any apologies. I don’t see any young earth creationist videos incorporating disclaimers about not wanting to offend people who accept real science instead of trying to square-peg-into-round-hole the pursuit of knowledge to satisfy their religious beliefs. You mentioned a KZbin channel - do you have a science/geology one? Are you allowed to mention what it is in the comments for this channel? If so, I’d like to check it out. Oh, and what makes you think I’m a “sir?” (assuming it was my comment you were responding to).

[@John_Weiss]

@@cedarwaxwing3509 I think someone needs to tell @rokualvin6428 to stop acting out while The Grownups are talking, because it's quite rude. As is his behavior. 😉

[@rokualvin6428]

​@@cedarwaxwing3509 I am truly sorry, Sir or Madam, for offending you while trying to be polite. When I took typing in high school, on a manual typewriter, letters were written, Dear Sirs, for official correspondence. It was not intended as a slight towards you. I watch KZbin videos on a laptop connected to my TV set. I created a channel with little content to login with for this purpose: Roku Al. When I make a comment I use this login, unless I am on my office computer which is logged into main channel. This video's title is just what a YEC would assume was an attack on his god and his worldview. On KZbin it is very common for them dog pile onto a comment section and make a mess. Geo Girl attempted to head them off at the pass. In the process, she triggered you--and based upon what you said, others--to do what the YEC might so, in complaining about her acknowledging that such people exist. They do exist and pretending that that they do not is unrealistic. I do not have a geology channel. My channel is called INTJ Island and the video I was referring to was called "The Rogue INTJ." It somehow pulled in a number of YEC unhappies. I did another video on the flat earth, where I was asking my viewers if they thought the Flat Earthers really believed it, or were just trying have fun with rational people: "An INTJ Take on the Flat Earth Myth." Minutes after I uploaded that thing I got hit with a bunch of negative comments and to this day, that video has more dislikes, from all those unhappy flat earthers, than all the rest of my 130 videos combined. Welcome to KZbin. Geo Girl is not on a slippery slope, as you can tell from all her many videos, where no such disclaimer was made. In this one, however, the title could easily pull in people who have no real interest in geology, simply to attack. It was a potential trigger, and she disarmed it. Science, for some people, creates a boiling emotional sea under the surface: belief vs knowledge. And it isn't just the YEC crowd either. So much of human existence is wrapped up in this problem. It is what makes both politics and religion such confrontational issues. It has always been so, to some degree, and it will remain so, until mankind evolves into a truly intelligent species. Meanwhile, like all creatures, we must be adaptive to our imperfect environment. (Which includes Young Earth Creationists.) My point was that if you choose to be stubbornly autocratic towards those who have no clue what you are talking about, it could well only make them more determined to oppose you. On the other hand if you keep personalities out of it, and treat them like real people who deserve to be included in your presentation, you will have far better success in making them think. I know this from personal experience. As I pointed out before, this is not PhD dissertation, or even an accredited classroom; it is a KZbin video. I applaud Geo Girl getting this potential problem out of the way early. Being polite is a virtue, not a vice, and it is not a slippery slope. At least that is my opinion for what it is worth.

[@user-gp8os8jp5v]

You are the best channel on youtube that explains a geosciences correctly and amazing! I am now intensively preparing for the International Geography Olympiad (iGeo) and your videos help me a lot!

[@GEOGIRL]

So glad to hear that, thank you and best of luck! ;D

[@spindoctor6385]

I loved the video, I think you could do without the disclaimer at the start. It almost seems like an apology. If people are going to get offended by information then no amount of apologising would appease them anyway.

[@nachog2041]

Great video Geo Girl. Am always fascinated that someone can ask a simple question but to get to the answer takes a whole journey of discovery.

[@GEOGIRL]

I know right, I actually didn't know about all the details of this journey until I had to research to make this lecture, and I find it SO interesting :D I mean the fact that they thought of so many different ways to try to estimate Earth's age is so cool!

[@stevenbaumann8692]

You really shouldn't apologize for the science. People can believe what they want. It's not your problem. The science is independent of their beliefs. Great video. I like how you tied RD into Steno.

[@vicbertfartingclack4559]

Love your channel Steven!

[@davidvogel1756]

I concur, Doctor.

[@Kreationcreatures]

That is not science by stating "WE KNOW" because no one knows how old the earth actually is.

[@davidvogel1756]

@@Kreationcreatures Stop, already, will you?

[@Kreationcreatures]

@@davidvogel1756 I will expose all claims no one knows how old the earth is.

[@matthewdolan5831]

My fave for earth history - I listen in background - keep having to rewind to get it all. Thanks.

[@mackinlayrandall9746]

Brilliant, concise, presentation with excellent graphics. Thank you.

[@jacquespoulemer3577]

Geo Girl, I concur with the comments below that this is a wonderful, well thought out and clear introduction to radiometric dating. I'm a 70 year old, mostly autodidact who has a wide range of intellectual interests. Since so many areas of human thought are in my purview, I appreciate that you covered not only the basic earth science, but a bit of history, and the olive branch to the YEC community (which worked by the way, I read all the comments and there wasn't a single negative comment). Merci Beaucoup, Vielen Dank, and muchas gracias, Jim Oaxaca, Mexico

[@vicbertfartingclack4559]

Although thoughtful, I really don’t think you need a disclaimer when sharing scientific facts. If someone really feels offended perhaps they aren’t quite as confident in their own beliefs after all. This subject isn’t a matter of opinion or belief. Plus, you never once attempt to diminish, ridicule or dismantle the beliefs of others. Btw, this is a tremendously interesting video and very well done! Thank you!

[@GEOGIRL]

I don't think I should need one either but you'd be surprised the comments I get.... LOL In any case, thank you for the comment, I am so glad you enjoyed it ;)

[@a.randomjack6661]

@@GEOGIRL I am not surprised, but I fin'd them depressing. I used to educate people on G+ about climate change Physics, generally in French 🍷

[@paulohagan3309]

@@GEOGIRL 'you'd be surprised the comments I get' I come alas, originally from Northern Ireland where there is an actual political party made up of people who would forcefully disagree with you by a few billion years [- not +]. on the basis of a certain book. So no, I would not be surprised, not at all. 😁😁

[@justmenotyou3151]

@Paul O'Hagan we in the US have those too. They're called Republicans. They are among the evilest people there are.

[@AMorgan57]

These days you can't be too careful. Lives are ruined over nonsense. It's a tragedy, so needless. Fundamentally, it's two separate systems of thought. One is scientific, the other is faith. Faith doesn't have to answer to science, and science doesn't have to answer to faith. We will, in consideration of those who disagree, invite them to send their comments to your wonderful science channel via their choice of tin cans and string.

[@gaufrid1956]

You made it easy for me to understand the science behind radiometric dating. I have always loved geology so I really appreciate your channel!

[@JP-jh6ki]

Oh i forgot to say that I really enjoy your channel. I especially liked your videos on pre-Cambrian to end Permian/Triassic life. Thank-you for making these videos

[@GEOGIRL]

Thank you!

[@amacuro]

This was very interesting. Thank you. The bit where you explain the geologic time table, made me wish there was a video telling the history of how every name (Silurian, Eocene, etc) came about and how they determined the different boundaries. A history lesson that would also teach so much geology :D

[@GEOGIRL]

Oh that would be such an awesome video! Thanks for the idea ;D I am writing it down now ! Just to be clear, I have no idea why they are named these names, but I would LOVE to learn about that (hopefully enough to make a good future video :))

[@nicholasmaude6906]

@@GEOGIRL The Cambrian for example got its name from Adam Sedgwick who named it after Cambria (The Roman name for Wales) as the best examples of Cambrian rocks in the UK are found in Wales. The Silurian gets its name from Roderick Murchison who named after the Silures (Another Roman name) an ancient Celtic tribe in Cambria (He was inspired by Adam Sedgwick), the Ordovician got its name from the Ordovices tribe and the Devonian got its name from the southwest county of Devon. See this map ( en.wikipedia.org/wiki/File:Wales.pre-Roman.jpg ). If you're wondering why all of these periods got their names from British counties and tribes well back in the 19th century the new field of Geology was dominated by the British and the Scottish in particular.

[@leechild4655]

@@nicholasmaude6906 I remember hearing some of this and so too are like the names given to Moons of planets in our solar system, as well as constellations, etc, man is the measure of all things they say.

[@markdover3825]

The Ediacaran period is named after the Ediacara Hills in South Australia because that’s where most of the fossils from that period were discovered.

[@davidvogel1756]

@@markdover3825 I believe most if not all of the nomenclature is based upon geography, when you get to the Period level and below.

[@angeluomo]

I just wrote a chapter in a book on this subject; and you hit all the main points without fail. Great job. You could have given Marie Curie a bit of credit for the discovery of radioactive substances, but otherwise you were (as usual) thorough, professional and pedagogically efficient. Your channel does a great job at explaining complex subjects in geology. Bravo!

[@johnnyBrwn]

Jesus, you're a fantastic educator. This is so dense you made it seem easy. Fantastic combination of expertise, patience, and thoroughness.

[@GEOGIRL]

Thank you so much! This comment made my day :))

[@astrokevin92]

Hi Geo Girl. That's perfect, thank you. I really enjoyed this video. I even took notes :) If I may, I'd like to add to your explanation of how we know the age of the universe. I don't know much about geology, but I'm a recent astronomy graduate. In a few words - from General Relativity we have equations (the Friedmann equations) that tell us how fast the universe will expand or contract over cosmological time, so long as we know how much energy it contains, the forms in which that energy exists, and how fast it's expanding today. In the past 25 years or so, we've measured the amount of normal matter, dark matter, radiation, dark energy, and the rate of expansion to a good precision, and therefore we can solve the equations to calculate the scale of the universe at any moment in time. So when we measure light from some very distant galaxy, that has a redshift of (say z=11) this means that the universe was 12x smaller when the light was emitted than it is today. So we can look at our equations and work out when the universe was 12x smaller (the answer is 13.4 billion years ago) and then start figuring out how far away it originally was such that the light took this long to reach us, etc. But we can also ask when the universe had a scale of zero. Because that's when the Big Bang happened, and the answer is 13.8 billion years ago. We can (and do) cross-check this with estimates of the ages of some of the oldest stars, most of which appear to be in the 12-13 billion-year range, but estimating the age of individual stars has fairly wide uncertainties. So in truth, our knowledge of the age of the universe is primarily based on having good quantitive information about what the universe is made of, and how fast it is expanding, that we can type into some equations and solve. Having these equations is also how we can interpret the measured red-shift of galaxies as times and distances, and of course, the speed of light is important in this, but the speed of light and redshift on their own, don't really directly tell us the age of the universe. Hope that's helpful.

[@GEOGIRL]

Ah, thank you so much for this information! That clears so much up for me! I hope the viewers will find this comment, because I am definitely not as well versed in astrophysics haha ;D

[@jimmyquigley7561]

Neat, concise, comprehensible and accurate. An enjoyable rapid revision of stuff I studied long ago.

[@johnholly7520]

I love your videos because they are in depth and not as superficial as other content on YT.

[@markocska94]

I am glad that your channel is starting to gain more views! I only discovered you a few days ago but I am hooked. Thanks for delivering such quality content for so long, even back when your videos averaged hundreds of views for so long

[@giovannicaproni6489]

Thank you for this extremely interesting video. As an amateur, I've generally been familiar with the various dating techniques, but your explanation has tremendously increased my knowledge. I understand it!! Thanks again.

[@GEOGIRL]

So glad to hear that! I actually learned A LOT in the making of this video as well, and I also found it incredibly interesting :D There's always more to know! ;D

[@a.randomjack6661]

@@GEOGIRL "The teacher learns more then the student" Douglas Adams, Can'r remember in which one of the 2 Dirk Gently's novels he said that, but I think it's this one "Dirk Gently's Holistic Detective Agency ". Great book. Astrophysicist made me discover Douglas Adams.🤓

[@calinradu1378]

That's fascinating Rachel! So much information in such a small space of time...definitely more relaxing then reading Wikipedia articles on the same topics😄

[@esslar1]

This was really well done. I've read bits and pieces of much of what you cover but you put it all together so nicely. I really enjoyed this. Thanks!

[@harrietharlow9929]

Very interesting and informative video. I now feel that I understand radiometric dating' Might I suggest a series on milestones in geological science, beginning with James Hutton? I discovered the Nuvuagittuq greenstone belt recently and if Professor O'Neil's dating figures eventually hold up, it is the site of the oldest rocks on earth at 4.2 billion years old There is controversy about that date and dating ranges from 3.7 to 4.2 billion years.

[@GEOGIRL]

That is a great idea for a series! Thank you! :D

[@harrietharlow9929]

@@GEOGIRL You're very welcome!

[@TheSunAndTheMoonrising]

I just found you on KZbin last night and have been ingesting your insights. I find your style of divulging information quite effective for those of us who are literally layman in this area. Keep up your wonderful work! 👏

[@GEOGIRL]

Wow thank you so much! I am so happy to hear that my lectures are digestible for those not in the field, that is great! ;D

[@firstnamelastname9918]

While not literally a layman, I am a literary layman. This is because I'm but a fictional character in a book that isn't yet finished and might not ever be done. So my only outlet is posting silly comments on youtube. :(

[@TheSunAndTheMoonrising]

@@firstnamelastname9918 I am so sorry for you. I hope someday that you will actually become a real boy. Maybe you might suggest an empathy and compassion algorithm installed into your matrix from your creators.? I understand that it is helpful for many of you who are not quite sure where reality and fantasy meet. My best regards

[@TheSunAndTheMoonrising]

@@GEOGIRL you are welcome. Ignore the naysayers and continue doing great things.

[@muzikhed]

I thoroughly enjoyed this one too Rachel. So much detail explained so well in just a few minutes. Nice. Cheers !

[@fiegenfiegen]

Thank you! With your videos I am finally learning about things I always wondered about. Great work.

[@slimgrandy9927]

Finally found gold,☺ not pyrite this this time... I could not dare miss your lecture if you were my professor at my college. Could understand the lectures, admire that cute face, and listen to that laugh and voice. (sorry couldn't resist, it's a W). 😅 Geo Girl Rock! 🤩🙌

[@GEOGIRL]

Hahaha, tell my students that, who only show up if there's a quiz! 😅

[@neddyladdy]

We asked it nicely, with politeness and tact if it would like to go out to a dinner/dance date and it all developed from there.

[@michael.mcshan]

Very good presentation of this topic. I just discovered your channel a few days ago and have enjoying your videos a lot.

[@dmj4489]

I love this video! You are explaining the topics so good! ❤

[@GEOGIRL]

Thank you so much!

[@mikesully7212]

thank you! you’re great : )

[@ramchauhan5238]

Best explainer of geology....✨✨ very nice geo girl...keep it up ✨✨✨

[@GEOGIRL]

Thank you!!

[@ramchauhan5238]

@@GEOGIRL most welcome .✨💖

[@hobart0011]

As a paleo educator myself, I feel that intro and understand why you said what you said. Love the channel!

[@ronschellhas9461]

Thank you! I learned a lot tonight! And as others have said, don't worry about stepping on anyone's toes. The ones feeling hurt, wouldn't worry about stepping all over you!! Keep up the great work!!

[@kevincraig9704]

I was gonna jump on the 'dating Earth' bandwagon, and how dating Earth and dating the universe had to be more than a world of difference, but then you talked about relative dating, and I was like 'Woah! Everybody knows that's just wrong!" Anyway, I love your vids. You break it down so well that one doesn't need a great deal of science education to understand what you're talking about. If everyone was forced to watch your vids, the earth would (probably) be a far less ignorant place.

[@GEOGIRL]

Thank you! But wait, relative dating is not wrong though... I mean relative dating is 100% accurate if done correctly, it's just not quantitative. Sorry if I didn't get that across well :)

[@sananton2821]

@@GEOGIRL He means dating your relatives.

[@JP-jh6ki]

I am Canadian and it always amazes me that science folks in the U.S. have to preface that they are not trying to insult anyone's belief and that this is a scientific discussion before discussing anything older that 6000 years. It is the same in many of your elections where a candidate has to say they are Christian and attend church in order to win. I am 57 and have always kept up with politics and cannot remember once a person running for federal or provincial positions even mentioning they are religious. What happened to separation of church and state? Ok go ahead and slam the foreign heathen.

[@chrisconnors7418]

I’m Canadian too, and this is also what I’ve observed about our politicians.

[@GEOGIRL]

It amazes me too, to me politics and religion and science should all be separate things and should not become enemies, but here in the US it seems sometimes they blend together and sometimes they become enemies when they shouldn't... I hope things will become separated again in the future but we shall see haha

[@dukecity7688]

It's infuriating.

[@SeaScienceFilmLabs]

Wow… Is that really how you feel???

[@SeaScienceFilmLabs]

There are Canadian “Young Earth Creationists…” 👋

[@Edgarbopp]

This is super well explained. Thank you!

[@unl0ck998]

This channel is criminally undersubscribed.

[@tedmaire1599]

Interesting stuff. And because I have to.... Geology Rocks!

[@davidvogel1756]

[@ManguKing]

I feel obligated to come down to the comment section and tell you that you are awesome!!!! Do not let trolls bother you. People can't handle seeing others do what they themselves can't do. They'll attack your character, your message, anything they can get their hands on Up to you of you let them break your peace of mind or just do you

[@GEOGIRL]

Wow, this really made my day, thank you so much for these kind and encouraging words!! It really helps ;)

[@billroberts9182]

Excellent discussion! Thx.

[@nickbuffa1814]

Thank you for your videos ❤

[@thelostone6981]

Great content and informative as always! There was a fun (to me) “mission” when one of the Apollo missions moon looked for and found, a “Genesis” rock. They geologists working for NASA knew that one of the moon’s surface should have some rocks from the creation of the moon and by Bon Jovi 😂 if they didn’t find one! Even after 40 years, they are still are cutting pieces off of it for scientific studies.

[@PraiseDog]

We owe a huge debt to Clair Patterson. He battled the Oil companies to get lead removed from gasoline. The Oil companies knew it was toxic, but it was a cheap way to deal with spontaneous combustion in engines. Read about the work of Thomas Midgley Jr. in Wikipedia, the devastating impact the man had on our atmosphere. We were able to deal with the depletion of the ozone layer, but the lead we breath in will be with us for a long long time.

[@GEOGIRL]

Absolutely, couldn't agree more!

[@michaeljames4509]

Thank you for this. It filled in a lot of gaps in my knowledge.

[@supmit2k8]

Thanks for the video... Much appreciated.

[@macarelcon]

Merci pour cette vidéo. Très intéressante je te regarde depuis la France.

[@JP-jh6ki]

Bonjour du Canada. Je suis né à Bayonne, Mais je suis de Capbreton.

[@GEOGIRL]

De rien! Merci pour le commentaire! ;)

[@nw5524]

It is truly inspiring to look at the history of science and realize just how far we have come since the 1800s. We have progressed from the early attempts of absolute dating all the way to the uranium-lead dating of meteorites. Who knows what we will discover in the future?

[@GEOGIRL]

I know right, when I read about it it seems like a long time ago, but honestly it was SO fast! I cannot wait to see how science advances in the coming decades :D

[@timothybull2929]

Another brilliant video by Geo Girl. Thank you so much for creating such accessible, clear and engaging explanations for all these geological processes.

[@GEOGIRL]

Thank you! :)

[@davidniemi6553]

Thank you for the excellent explanation! I have not heard such a clear explanation of geologic dating anywhere else.

[@m.w.5972]

Honey I don't need to know what relative dating is, I'm from Alabama! Just kidding, I'm actually from Poland and love love the video lol

[@GEOGIRL]

Hahaha thank you ;)

[@legendre007]

Thank you for this informative video. 😊 It's interesting how geologists must also apply discoveries in chemistry and even molecular physics; it's so multi-disciplinary. 🤔 I thought you might mention how, during the Enlightenment, James Hutton -- who knew Erasmus Darwin, Adam Smith, James Watt, and David Hume , and who inspired Charles Lyell's work-- cited sedimentary rocks to point out the Earth had to be much older than thousands of years, even though not even he knew it was _billions_ . 😊

[@harrietharlow9929]

Right. I think the figure 1 billion was arrived at by Arthur Holmes in the 1930s or 1940s. He also suggested that the underlying mechanism of continental drift was convection in the mantle. James Hutton was da bomb! He actually could be considered to be as one of the founders of geological science, at least IMO. I love how he phrased that the earth is vastly old--"no vestige of a beginning and no prospect of an end". Of course we now know it had a beginning and will have an end, but it was a beautiful phrasing of the scientific uncertainties of his time.

[@GroupieImp64]

Fantastic, thank you!

[@subhashsaxena6802]

Very beautifully explained.❤

[@thor9517]

Love the way you explain things, makes it really easy to understand. Thank you and keep up the good work. :)

[@robertkelleyroth409]

I liked the history lesson. Lots of smart people guessing with the data they had at hand.

[@GEOGIRL]

I know right! It was so cool for me to learn about these estimates because I thought it was awesome that they were all so far off, but worked together and kept trying until they got it right and it all made sense! The story of how it all finally happened is so cool to me :D

[@sayagarapan1686]

Thanks, Professor. Very interesting subject, one I've only had a glance at. I have beliefs. Some very strong ones. And just like my scientific beliefs, much of it is verified by observation. I don't often tell people about them because their eyes just glaze over and an alarming disconnection occurs (Okay, I admit it's a little funny, too). But encompassed within my beliefs are that of an earth that is very old, so this is useful science to me and I've been curious about it, so thank you for this video. Off the subject, you have the best laugh, btw. It's almost like you're saying, "I beg pardon. A little. But not really, hee hee."

[@GEOGIRL]

Thanks so much for the thoughtful comment. I really respect those that have beliefs especially when they backed up by observation ;) I am so glad you found this video informative. I am always worried to put videos over topics like this out there because I know some people won't be very kind if they have different opinions, but I hope it comes across that I really just want to educate not to offend or convert anybody. Also, thanks so much for the compliment about my laugh haha, I am glad you like it ;)

[@a.randomjack6661]

@@GEOGIRL The truth is what the facts are 🤷‍♂Specially when those facts have such clear explanations and can be verified. 🖖

[@davijimi]

​@@a.randomjack6661hum do you talk about god 🤔??

[@a.randomjack6661]

​@@davijimi Nope, never... Who's god would it be anyhoo?​

[@a.randomjack6661]

@@davijimi Religion begins with an snswer Philosophy with a question Science with an observation

[@ignaciot]

Every time rocks undergo remelting & recrystallization, isotopes are reset!! Oh, I didn´t know that so I couldn´t understand clearly how isotope dating worked. Thanks a lot!! Excelent channel, totally suscribed

[@Colestar1680]

Great video. Thanks👊

[@legendre007]

I know you have previously discussed plate tectonics during the Carboniferous Period. Have you also talked about how Marie Tharp's study of the ocean's floor contributed important evidence for plate tectonics, which they were still calling "continental drift"? I was thrilled by this story 😊, but saddened that the same men who first dismissed both her and Alfred Wegener later tried to take all the credit for her discovery. 😐

[@harrietharlow9929]

I found the entire Marie Tharp thing depressing. Here she found something that explains the opening of the Atlantic and what happens? Her discovery is dismissed as "girl talk". And yes others tried to take credit for her discovery. I think her discovery was epic--she discovered one of the drivers of plate tectonics, the other being subduction.

[@DJRonnieG]

I know I have problems when a bunch of rocks are more likely to be dated by geologist than myself.

[@lugnutdecepticon]

Great video keep up the good work!!!

[@GEOGIRL]

Thank you! :D

[@Quwucuqin]

Wonderful explanation and best so far in KZbin 👍

[@ramchauhan5238]

Good morning geo girl.....and good night for me.. because it's 10.03 pm in India 🙃🙃

[@chrisconnors7418]

Succinct and clear. If I was in your class I’d get high marks, not because I’m a genius but because you present things well. Slightly off-topic. I’m reading The Evolution of Charles Darwin. It’s following his five year voyage, quoting liberally from Darwin’s letters and diaries. Darwin said a few times he considered himself a geologist. It fascinated him and he made some preliminary stratigraphic profiles of South America during his many travels by horse or mule. Everywhere he went, it was the geology that he drew his eye. He considered various scenarios on how features and layers formed, and in many cases he was shown to be correct. Highly recommend the book. I’m about 50% done (he’s just left New Zealand). I keep reading it long past my bedtime as it is so engaging.

[@GEOGIRL]

Aw thank you so much! But how do you know I am not a super hard grader? LOL just kidding! I am glad to hear that, I hope my students feel the same ;) Thanks for the book recommendation, I haven't read that one, but now I am convinced I must, it sounds so amazing! Haha :D

[@brianbuch1]

The book he himself wrote, "The Voyage of the Beagle" made Darwin famous and was a bestseller. It's great that there are books about Darwin, but he was quite a spellbinding writer. His last book, with the somewhat intimidating title "The Formation of Vegetable Mould through the Action of Worms with Observations of their Habits" is both fascinating reading, and an example of how Darwin and his mind worked. As with "Origin" Darwin worked not from the top down (as creationists love to do) but from the bottom up, from the worms, the corals the barnacles, and the pigeon and dog breeders, to develop his theory.

[@robertforrester3158]

Thank you Geo girl.

[@bcddd214]

You are a brilliant girl! You're also drop dead gorgeous and then some. Your lighting and and makeup is not doing you justice at all. I, know. Its the content that matters here but, you're just too hot not to try and capitalize on it a little. It looks like your just took the lampshade off to give you enough light. It created a ton of glare. I just googled professional camera lights for $50 and it upchucked Amazon. If that's not in the budget, try 3 or 4 more lights in the room, all with lampshades. The Hollywood trick ideal makeup is just a smidgen of base, one single shade darker than you think you need. Then a little powder to kill any glare. I adored the video and just liked, subscribed and hit the notify button.

[@mspicer3262]

Some of us are out here hoping you'll have a stint as NASA GIRL... or maybe EXO-GEO GIRL... now broadcasting from Ceres with a 25-minute light delay...

[@GEOGIRL]

Hahah Love that! Hopefully someday ;D

[@thehairywoodsman5644]

GEO GIRL - " I love geology ! " EARTH- " you want date me ! " lol awesome you posted today , I hope you n yours had a magnificent Thanksgiving !

[@GEOGIRL]

Thank you for the Thanksgiving wishes, it was great! I hope yours was as well ;)

[@ksphinney1]

Thanks for all you do. You are helping me pass my Earth Materials class. I’m 70 and need the help!

[@ADVBear]

Great video. Subbed.

[@WhiffenC]

Hmm very convincing... However I think I'll still have to stick with the story, by the unknown authors, that its only 300 years old and that bushes/snakes talk to them. I mean, how can you refute something like that? Jk great video.

[@NelsonDiscovery]

Heyhey! I'm watching a video of yours only one hour after upload. A little sad how youtubers feel the need to apologize to pressure groups like this while many youtubers (not you) feel no shame using words that are abusive to people with psychological disabilities and other unorganized minorities all the time. Religious people who feel uncomfortable with certain areas of geology should just watch videos made by people who tell them what they want to hear.

[@GEOGIRL]

I know, I feel like for the most part they do, but sometimes I'll get comments that clearly came from people who just came to argue so I just wanted to put it out there that I didn't want to argue hahaha. I also have close friends that believe a young earth and I would never want them to feel offended by what I teach so I that was another reason I wanted to make it clear I wasn't trying to offend anyone's beliefs in any way. :) But I agree, it is a bit sad that I have to say that...

[@pingobongo]

Absolutely outstanding post! Jolly well done!!😊 Excellent!! 🤠🌍 Greetings and very best wishes from Englands Northwest!!

[@Pyrolonn]

I admire your commitment to geology that you actually date rocks.

[@erictaylor5462]

The age of the Earth is still 4.55 billion years old, even if you believe it is younger. It blows my mind how religion works its way into culture and how some people think that reality should conform to our desires. On top of that, if you point this out to some people they actually become offended. It's as if they know, on some level that what they believe is not true, but they *WANT* to believe it's true so much that they are willing to lie to themselves to believe in it. If you can't be honest with yourself, you can you be honest with anyone else?

[@mcloutier5]

I'm pretty sure it was a Wednesday, shortly after tea time.

[@greenreptile5650]

Big thank you for making it so easy to understand, I'm extremely disappointed in my education for not providing a more detailed and longer background in dating Earth, cause recently Young Earth creationists have been around my circles and though I've never taken a deeper interest before in the topic, their consistent pushing of their narrative made me go down this path. I'm pretty sure Einstein said something about one not understanding the subject well enough if you cannot explain it in simple terms, and so I'm trying just that.

[@justmenotyou3151]

Nice job 👍

[@charlesjmouse]

Thank you for the video. A question: I understand how and why today's parent / daughter ratio along with half life can be used to calculate timespan but how does one know that ratio is entirely the result of decay since the sample formed? It may have contained the daughter product at formation in an amount hard to determine. Is it simply that radiometric dating is only done with samples that could not have chemically included the daughter product on formation? (Or a parent that is presumed to have a constant formation rate, such as C14)

[@GEOGIRL]

The daughter isotopes are lost to the system during melting. When material re-melts the stable daughter products that had formed through decay remain in the melt when recrystallization begins whereas the radioisotopes are incorporated into the solidifying material leading to the regeneration of 100% parent isotopes and no daughter because the daughter isotopes are not stable as solids in those high energy (high T and P) conditions, whereas the parent isotopes are. Now, the "clock" for a particular mineral doesn't start until that particular crystal becomes a closed system. The rate of diffusion of atoms in and out of the mineral structure is temperature dependent. There is something called the 'closure temperature' that once a mineral cools below, it will become closed (because the diffusion becomes very slow it's basically negligible) and the clock starts at this point when the mineral fully crystallizes and stops interacting with the surrounding material. I also want to specify that there are some isotope systems in which measuring parent to daughter isotopes is a bit difficult because there is, for example lead, incorporated into newly formed rocks that we want to date using uranium-lead dating. Thankfully, however, I believe for the most part we can measure the difference between stable (non-radiogenic or radioactively produced) lead isotopes vs radiogenic lead isotopes, which allows us to still calculate the correct age. But I do think there are general background concentrations of daughter isotopes that are considerd in the calculations, but I am not a geochronologist, so I don't rememebr which isotopes systems require these considerations and which don't. Anyway, I hope that helps a bit (again, I am no expert in geochronology, this is my best understanding) :)

[@SeaScienceFilmLabs]

@@GEOGIRL What I’ve come to understand about these “Dating Methods,” is they are inaccurate in dating things with a known age… 🤔 What’s your opinion on that??? 🍎 And, again: Where on the planet can I go to view the “Geologic Column?” 🍎 Is there a place where all the layers are connected in sequence???

[@jameshall1300]

@@SeaScienceFilmLabs when you try to carbon date a sample from Mt St Helens that's less than 50 years old, of course you're going to get ridiculously incongruous dates. There's a range within which different dating methods work, but somehow creationists always seem to use the most inappropriate one....weird, almost like they want the method to fail 🤔

[@dany_ltv]

Here an interesting wiki about it en.wikipedia.org/wiki/Lead-lead_dating The rest is what I understand from the wiki. I'm no expert. There is 2 problems. 1 The presence of non-radiogenic led but we deal with it with the ratio of 204Pb/206Pb So we know how much non-radiogenic lead (naturally occuring 206Pb) is present in the material and how much additional 206Pb was add due to radio isotope decay. 2nd we need to know the original condition so the original 238U/235U ratio. It was found that it varried a bit from different meteorite. This problem is harder to solve but we use a mean value. You need to know the initial amount of Uranium vs the present amount of Lead to calculate date rock.

[@SeaScienceFilmLabs]

@@jameshall1300 🤣 Sounds good!!!

[@David_Goza]

It's aggravating that you even have to issue such a disclaimer as at the beginning. Love your work.

[@feathertail-dinosaurs]

Rachel! Your content helped me get started on making my own KZbin channel, but how on earth do you present so well on camera? 😭 I'm much more comfortable speaking behind a mic, but keep up the good work!! 🎉🎉

[@GEOGIRL]

Hahaha it took a lot of practice... go watch my first video, I did not talk/act like this 😅 Trust me, you'll get there, justt keep going!! I just subscribed ;)

[@feathertail-dinosaurs]

@@GEOGIRL Thank you for the encouragement!!!!!! 💖💕💖💕

[@markcraig1389]

Well done! I’m a new subscriber! I’m going to binge watch your videos tonight! I’m a “basement geological enthusiast” with an open mind. I’m at odds about the earths core though. I don’t believe the current narrative. I think it should be investigated with an open mind to the possibility of a plasma core.

[@thesunexpress]

It wasn't last Thursday after all?!

[@eljanrimsa5843]

No it was first Thursday

[@thesunexpress]

@@eljanrimsa5843 "This idea is sometimes called Last Thursdayism by its opponents, as in "the world might as well have been created last Thursday." " en.m.wikipedia.org/wiki/Omphalos_hypothesis

[@joemcgarry1106]

Those that don't believe in science should look for a flat earth channel.

[@robertcampbell6349]

Sadly, there are plenty of those around.

[@dennis_mihaylov]

Thank you very much!

[@Evildragonfirez]

Cool video idea... a video dedicated to the chicxulub impact. T Rex and the Crater of Doom is my favorite book. I love your content btw - Free, quality education. Educators make the world a better place.

[@a.randomjack6661]

Clair Paterson should deserve a video og it's own. Mot only did je find out the age of our planet, nut he also realized that leaded fuel was contaminating said planet. He advocated to have lead removed from gazoline where it served as an anti-knocking agent. We all know, or should know, how lead affects our health, but that's a different story. I learned most of this in a Cosmos episode by Neil deGrasse Tyson, not my favorite science explained btw, you do a much better job. 👍 Thank you

[@BackYardScience2000]

Whole heartedly agree!!!! 💯😃

[@GEOGIRL]

Yes! I agree as well! I didn't even know about his role in removing lead from gasoline until recently when listening to the Ologies podcast (the geology episode), and I already thought he was awesome before that! ;D

[@a.randomjack6661]

Thank you@@GEOGIRL He should be everyone's hero 🦸‍♂

[@rockets4kids]

It's really sad you need to start a video this way these days.

[@GEOGIRL]

Yea, I went back and forth on whether to include that and I still don't know whether it was the right move, but after being on youtube for a couple years, I think I am just terrified of people in my comments lol so I just wanted to start off with... "if you don't believe this, leave the video" lol I don't know how else to avoid confrontational comments. I think the answer is I shouldn't care so much, I just have a hard time with not caring because I am such a people pleaser.. but I am learning haha

[@alanfarrance8639]

Rachel, Most of us easily grasp how radioactive decay and half life contribute to dating but the absolute elephant block to understanding is how the initial conditions are set. How do you know what the initial C12/C14 ratio was when a plant grew (maybe I know the answer to that one), but I have no idea how you would know the initial U/Pb ratio in a rock when it is formed.

[@jamesdubben3687]

Nicely done. The part of science underappreciated is that trying to prove something wrong is very useful. It leads to new ideas. The flip side is, oh it gave the same answer is equally strong with valuable corroboration.

[@brentwilbur]

I appreciate your intent, but you are under no obligation to couch religious fanaticism - both the contradictions inherent to Abrahamic creation mythos *AND* the woke rite of advanced prostration for potential offense (often consolidated into the grotesque canonical "trigger warning"). You are a geologist. You see the world a certain way and your sheet music is composed of lines in the rock. If people want to take offense, that is on them. To _ignore_ is a conscious act. Ignorance is deliberate and not a biological condition. The choice to remain ignorant should never be used as an excuse to abuse people, but neither should it be directly facilitated. You can know their stories, but will they ever take the time to know yours? I don't think so. Do your thing angel, with or without approval.

[@GEOGIRL]

Thank you, and yea, I know I just wanted to preface this video in particular because I personally have many friends that believe in a young Earth and I love my friends and would never want to offend them so I just figured I would try to warn off the people that may have been offended by or disagree with what I say here, but I know I shouldn't in theory 'have' to haha

[@brentwilbur]

@@GEOGIRL - If it's genuinely in you to approach life in that kind of peacemaking manner, you gotta do you. It's the often-associated sense of forced obligation I despise. Anyways... keep it coming.