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: https://amzn.to/3v1Iy0G Exploring Geology Textbook: https://amzn.to/3AM4CC7 Lord Kelvin and the Age of the Earth by Burchfield, 1990: https://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: https://amzn.to/3gAAfYx Age of meteorites and the earth by Patterson, 1956: doi:10.1016/0016-7037(56)90036-9. Age of Earth: https://en.wikipedia.org/wiki/Age_of_... GEO GIRL Website: https://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: https://GEOGIRLTutoring.as.me/ Hey there, Earth enthusiast! Check my favorite Earth-friendly products: Bamboo toilet paper: https://shrsl.com/3cvku Bamboo paper towels: https://shrsl.com/3cvkw Compostable tableware: https://shrsl.com/3cvkz Compostable trash bags: https://shrsl.com/3cvl0 Bamboo cutlery + straw! : https://shrsl.com/3cwfl Eco-Friendly Tote (great for grocery shopping!): https://shrsl.com/3cwfp Reusable straws + cleaning brushes (my fav!): https://shrsl.com/3cwft Eco-friendly laundry detergent: https://shrsl.com/3cwgo Directly offset your carbon footprint with Wren: https://shrsl.com/3d0t2 (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: https://amzn.to/3gffbCL Brief history of Earth by A. Knoll: https://amzn.to/3w3hC1I Life on young planet by A. Knoll: https://amzn.to/2RBMpny Some assembly required by N. Shubin: https://amzn.to/3w1Ezm2 Your inner fish by N. Shubin: https://amzn.to/3cpw3Wb Oxygen by N. Lane: https://amzn.to/3z4FgwZ Alien Oceans by K. Hand: https://amzn.to/3clMx1l Life's Engines: https://amzn.to/3w1Nhke Tools I use as a geologist/teacher/student: Geology field notebook: https://amzn.to/3lb6dJf Geology rock hammer: https://amzn.to/3DZw8MA Geological compass: https://amzn.to/3hfbdLu Geological hand lens: https://amzn.to/3jXysM5 Camera: https://amzn.to/3l6fGRT Carbon-neutral pencil bag: https://shrsl.com/3cvjv Carbon-neutral backpack: https://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!