Bedrock: Earth's Earliest History

Until now, all the clues for ancient life have been microscopic, beyond the realm of sight. Today, that begins to change. Ten years ago, a team of scientists showed the world a weird, lumpy rock that they claimed was the oldest microbial colony. Like a sci-fi movie, this specimen was found under melting ice in the high Arctic, unveiled from 3.7 billion years ago. But is it actually a fossil? Welcome to the debate that has defined my corner of geology. Extra Credit: Check your house for hard water damage, or watch The Thing (1982). Want bonus content? Check out the Patreon!

This episode, we focus on just one special boulder from the Greenland tundra, a rock that might have Earth's oldest fossils. Over the past 10 years, scientists from around the world have used the latest technology to reveal this rock's secrets, including research published this year. What have they found? Extra Credit: Make a time capsule or play a record.Patreon for monthly donations One-off donations

Donate to support the show- anything is appreciated!Finally, 3.7 billion years ago, we reach some of the strongest evidence for life on Earth yet. It takes a while to find, and it only looks like a few dark crystals, but it's better than anything else we've seen so far. Along the way, we'll meet three scientists who helped define the quest for Earth's oldest fossils, including one of my old bosses.Extra Credit: Sharpen your pencils, spackle some cracks, or thank a mentor in your life.

Many folks have claimed to find Earth's oldest fossils in the Greenland rocks, 3.7 billion years old. Before we meet and judge these contenders, we need to learn what counts as a fossil. This early in Earth history, nothing has any bones or teeth or shells, so researchers need to search for other clues. Today, I'll show you four ways to look for fossils in Earth's oldest rocks, including my personal field of study: fossilized bacteria. Extra Credit: Find different types of organic carbon in your day, or eat a burger.

Donate to support the show- anything is appreciated!Today is a tale of two sisters: limestone and dolomite. Limestone is far more popular and well-behaved, one of the most common stones in nature and in architecture. Dolomite, though similar in many ways, is one of the most difficult rocks to make on Earth. Even dolomite’s name is a bone of contention. Today, we introduce both siblings to the show as we move forward in time, 3.75 billion years ago. Along the way, I’ll give you a real experiment to try in the kitchen and we’ll smash some stones together. Extra Credit: Try today’s kitchen experiment, find some limestone around you, or get some calcium in your diet (dairy, leafy greens, or tofu).

What was Earth's mantle like 3.8 billion years ago, and how do we know? The mantle is a realm that humans have never visited, and examining it is only harder in the ancient past. Fortunately, the mantle sometimes gifts us with beautiful green rocks from the deep, souvenirs of an unknown underworld. Today, we learn how the mantle has changed over time, and its surprising connections to outer space. On the way, we'll meet the father of geochemistry, revisit old asteroid friends, and learn why you should always flour your berries before making a cake.Extra Credit: Bake some blueberry muffins.Donate to support the show- anything is appreciated!

In 1971, two geologists traveled to the edge of Greenland's ice sheet. What they found were the oldest rocks known at the time, 3.8-3.7 billion years old. Shockingly, they were in decent condition, sparking a half-century of geology stories. Today we'll begin our tour of Isua, the final destination of Season 2. Along the way, we'll meet a Holocaust survivor who landed on top of the world, visit an iron mine surrounded by glaciers, and start to meet the highest-quality rocks of this season.Extra Credit: Eat some candy, some shrimp, or some Indian food.Donate to support the show- anything is appreciated!

Nearly 30 years ago, one paper claimed to find the oldest evidence for life on Earth. How does that evidence hold up in 2025? Are these fossils or duds? Don’t panic, we’ll answer these questions to life, the universe, and everything in due time. Along the way, we’ll meet the most abundant mineral in the human body, an important fertilizer, and finish a trilogy of intense debates over a small Greenland isle. Extra Credit: Read The Hitchhiker’s Guide to the Galaxy, eat cake with sprinkles, and make sure to floss afterwards.Donate to support the show- anything is appreciated!Click here for the audience survey!Click here to read Dylan's Nature paper!

How old is the oldest slice of Earth's seafloor? The answer is more contentious than you would think. Today, we visit one of the most debated locations in the show: a small island off the Greenland shore named Akilia. Everything about these rocks has been contested, and we'll meet three scientists who form cornerstones of the debates.Extra Credit: Watch something on an old CRT TV, or count tree rings in a stump.

This season's final arc is set in Greenland. Let's start with the most common rocks in the region: what are they and what stories do they tell about the world 3.9 billion years ago?Along the way, we'll weave a tapestry of stone, boil some rocks, and learn a bit about Dylan's birthstone. Extra credit: try the Play-Doh experiment from this episode, or make some stone soup.Click here for the audience survey!Donate to support the show- anything is appreciated!

Hi folks,If you’re a long-term listener, you know this show often takes long, multi-week breaks. This break has been much longer than normal, and will likely continue for a few months. What’s going on?Right now, I have one goal on my mind: to find a new, permanent job.My three-year contract at Grand Valley State University will end in April. I knew this going in, and it’s public information, so don’t worry about any dirt being spilled. In the past three months I have applied for dozens of jobs, and that number will double before year’s end.Each application takes time. I also have a full teaching schedule and I’m supervising undergraduate research. In short, there’s simply no time to make the show right now.I don’t know where I’ll be in six months, and that’s honestly a very stressful situation. But things are looking up- I’ve had a few interviews, and jobs are still being posted.When I find a permanent position, hopefully by early 2025, I will let you all know and finally return to Bedrock, both the show and in my own life. In the meantime, thank you as always for your patience and enthusiasm. If you’ve finished the show, you can recommend it to a science-curious friend. You can always drop a line at bedrock.mailbox@gmail.com, it always makes my day.See you next time, whenever that may be.

Why are some ancient rocks well-preserved, while others are extremely messed up? Today, we'll take a side quest from our Greenland arc to learn more about metamorphosis, which changes rocks beneath our feet. On the way, we'll transform toast into cookies, take an elevator ride deep into the crust, and meet an ancient rock with a babyface. Extra credit: make some toast, or go looking for butterflies.