Geochronology is the science of determining the age of rocks, fossils, and sediments using signatures inherent in the rocks themselves. Dating methods are: Radiometric dating, Fission-track dating, Cosmogenic nuclide geochronology, Luminescence dating, Incremental dating, Paleomagnetic dating, Magnetostratigraphy, Chemostratigraphy, Correlation of marker horizons.
4.4 billion-year-old zircon crystal is providing new insight into how the Earth cooled from a ball of magma and formed continents much earlier than previously believed.
Photo courtesy of John Valley
Timeline showing major events in Earth history. (Ga = billion years before present)
credit: Andrée Valley, University of Wisconsin
via ASAPScience: "What would it look like if we took Earth's 4.5 billion year history, and stuffed it into a normal day's 24 hour time-frame? Follow the magnificent journey of life; where it began, and how it eventually led to humanity as we know it. "
"Entertain your science classroom with a paper-cut animation video tracking the theory of evolution as formulated by Alfred Russel Wallace. Wallace independently formulated his theory of evolution by natural selection at the same time as Charles Darwin. This fun video animates Wallace’s life, from his boyhood in England to his voyages with Henry Walter Bates and his later adventures in the Malay Archipelago.
Learn about one of the founders of natural selection and the theory of evolution in this video, perfect for high school biology lesson plans. Co-directed by Flora Lichtman and Sharon Shattuck of Sweet Fern Production, this film provides an in-depth and entertaining look at Wallace’s life."
"In which John Green, Hank Green, and Emily Graslie teach you about, well, everything."
10-part video series playlist!
"With a solid understanding of biology on the small scale under our belts, it's time for the long view - for the next twelve weeks, we'll be learning how the living things that we've studied interact with and influence each other and their environments. Life is powerful, and in order to understand how living systems work, you first have to understand how they originated, developed and diversified over the past 4.5 billion years of Earth's history. Hang on to your hats as Hank tells us the epic drama that is the history of life on Earth."
"Do we take the Earth for granted? It gives us life and sustains us in the manner we're accustomed to, but we don't know the first thing about it: like where did it come from? And how did it form? Most people recognize that the Earth has a big explosion in its history, which they refer to descriptively as the 'Big Bang.' But there are two very good reasons why the Big Bang is not directly responsible for forming the Earth: 1) It happened 13.7 billion years ago. That's more than 9 billion years before the Earth formed (what happened during that time?), and 2) After the Big Bang the universe consisted of only Hydrogen and Helium - not great raw material for building the Earth. The truth is the big bang formed stars, which exploded and then (perhaps) formed more stars, which exploded and then formed our solar system, including the Earth. The early stars performed the vital role of making the heavier elements of which Earth is composed and we are made."
"Earth had a climate long before we showed up and started noticing it and it's influenced by a whole series of cycles that have been churning along for hundreds of millions of years. In most cases those cycles will continue long after we're gone. A look at the history of climate change on Earth can give us some much needed perspective on our current climate dilemma because the surprising truth is, what we're experiencing now is different than anything this planet has encountered before. So, let's take a stroll down Climate History Lane and see if we can find some answers to a question that's been bugging Hank a lot lately - just how much hot water are we in?"