Bedrock: Earth's Earliest History

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.

What is the hardest rock to make?

Today's rock is very common in Earth's ancient past, and it should be everywhere today. However, it's nearly impossible to form in nature or the laboratory. Some experiments have tried for 32 years with no success! This rock is dolomite. Today, we address The Dolomite Problem, one of geology's longest-running mysteries. Along the way, we'll meet some smelly but helpful bacteria, sort a fruit stand, and learn about the cutting edge of geology research.

Extra Credit: Eat some citrus, and check your home for natural gas leaks.

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...

What types of volcanoes were erupting 3.8 billion years ago?

Today, we meet a new type of rock and a new type of volcano, far more powerful and dangerous than those we've met so far. The old volcano is long dead, but the scars it left behind can still be seen across the Greenland landscape. Along the way, we'll learn how different types of lavas are made, why a few rocks can float in water, and learn about a field trip Dylan took to Iceland in 2010.

Extra Credit: Eat a grilled cheese sandwich, blow a bubble...

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...

What is the world's oldest slice of mantle, and how did it reach the surface?

Today, we'll meet the first tangible piece of the world below the crust, a world humans still have not visited. Along the way, we'll meet an old mineral friend from Season 1, a researcher named Friend, and learn how diamonds can be a geologist's best friend when looking for slices of the mantle.

Extra Credit: Clean your bathtub, or call an old friend.

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.

...

Two months ago, I made an audience survey focusing on one topic: how would you like to support the show?

Many folks answered, and here's what you said about donations, Patreon, ads, and merch.

If you want to give your own opinion, take the survey here, put a comment below, or send a message to bedrock.mailbox@gmail.com.

If you'd like to give a donation, you can click here- any amount 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...

In 1991, a mysterious, striped red and gray rock was discovered on a cold Greenland isle. Years later, this rock would rock the scientific world with multiple debates about the early oceans and life. What exactly is this rock, and why do we care? Stay tuned, and on the way, we’ll learn how scientists can officially argue with each other.

Extra Credit: Eat something with peanut butter and chocolate, pet a large and a small dog, or make sure your vaccines are up to date!

Donate to support the show- anything is appreciated!

Cl...

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.

Earth’s crust is shattered into dozens of moving plates, but many other worlds operate very differently. What are some alternatives to plate tectonics?

Today, we’ll compare tectonics on Earth with tectonics on other planets, through the lens of 3.9 billion-year-old rocks from Greenland. On the way, we’ll visit the westernmost town in the USA, visit one of our cosmic neighbors, and learn about the Occam’s Razor of geology.

Extra Credit: find today’s planet in the night sky, drop a pebble every day this week and see if anything changes, or read “The Long Rai...

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!

We're back! After nearly a year, Dylan has updates about his life and the future of the show.

Please take the audience survey in the link below to let Dylan know how you'd like to support the show! Also, please check out the donate button if you like what you've heard so far.

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...

Hi folks! I've just been invited by my university to join a field trip to Iceland next week, one of the best spots in the world to study geology. This means there will be a slight hiccup in our programming.

Episode 38 will drop early next week, while Episode 39 will hopefully drop the first week of August. If I have time and space, I might try some experimental episodes from Iceland itself, field diaries and interviews, but no promises yet.

As always, thanks for your patience and support!

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.

What is the oldest *major* slice of rock, one that's relatively well-preserved, one that's fueled a half-century of research?

The episode's name kinda gives it away, but stay tuned as we meet the last location of Season 2: a series of rocks near Greenland's capital. Along the way, we'll meet the different groups of people who have settled on this remote island, and a geologist from the other side of the world. I'll also take a brief detour into why I unfortunately can't talk about every single ancient rock out there.

Extra Credit: Find a choir...

How did the Man in the Moon form? What does the Moon's Far Side look like?

Today, we'll learn about the most visible remnant of the ancient world- the pattern of dark lunar rocks that stares down on us each night. On the way, we'll hitch a ride with a flying fax machine, play a game with crystals in magma, and learn why bananas are slightly radioactive (and why that doesn't really matter).

Extra Credit: Try to send me a fax, or just eat a banana.

When did the Moon's craters form? Can they tell us any stories about the ancient Solar System?

Today, we'll learn some early explanations for lunar features, meet a "lunatic asylum" of planetary geologists, and learn how the larger planets might have bullied their smaller neighbors.

Extra Credit: Watch Apollo 13, or The Right Stuff.

What are the oldest disputed fossils on Earth? Why are they disputed?

Today, we wrap up our tour of Nuvvuagittuq in northern Quebec, 3.8 billion years ago, March 3rd on the Earth Calendar. In 2017, microscopic rusty threads were discovered inside these rocks, thinner than a human hair. Were they bacteria, or something else entirely? Stay tuned to find out!

Extra Credit: Learn how to make a chemical garden, or find a piece of chert, flint, jasper, agate, or onyx.

Common Descent Interview: https://youtu.be/amQ9rntfKV0?feature=shared

Where does humanity get most of its' iron, and what do these rocks tell us about the ancient Earth?

Today, we'll learn about banded iron formations, the backbone of the modern steel industry an important stop in the search for early life and oxygen, and a rock that is impossible to make today. It's rare to find a rock as important to both economics and research. Along the way, we'll take a breath of fresh air, meet orange pond scum in a forest stream, and find a dagger carved from a meteorite.

Extra Credit: Find...

What are Earth's oldest volcanic rocks, and how did they form?

Today, we'll explore the seafloor 3.8 billion years ago through dark basalt rocks in Nuvvuagittuq, northern Quebec. Along the way, we'll earn a green belt in geology, rest our heads on volcanic pillows and journey to the deepest spot in the modern ocean.

Extra Credit: Try to find dark black basalt in a building or countertop near you.

What's the next step after the oldest rock on Earth?

Today, we'll move the story forward 200 million years and 1,000 miles.

The time: 3.8 billion years ago... or maybe much older (March 3 on the Earth Calendar).

The place: Nuvvuagittuq (noo-voo-ah-git-took), Quebec, Canada, in the lands of the Inuit.

In this episode, we'll learn how this seaside outcrop was found and the ongoing debate about its' exact age. Depending on who you talk to, these are either the second-oldest rocks on Earth, or almost as old as the Earth itself.

If the sun was dimmer 4 billion years ago, how did the Earth stay warm?

Today, we learn how just a small percent of Earth's atmosphere goes a long way in controlling global climate, both today and in the ancient past. Along the way, we'll visit an imaginary frozen Earth without any sun, a hazy giant moon of Saturn, and learn exactly what the greenhouse effect is.

Extra credit: Visit a greenhouse, or find a cleaning product with ammonia.

How has the Sun changed over the past 4 billion years?

While the Sun may seem unalterable, it has brightened dramatically over Earth's history, with major implications for our world. Today, we'll meet a team of women who catalogued thousands of stars in the 1800s, play in a galactic ball pit, and puzzle over a cosmic paradox alongside Carl Sagan.

Extra Credit: Watch Cosmos (1980)

Is there any place today that resembles the Earth 4 billion years ago?

Surprisingly, the answer is yes... ish. Today, we'll learn a secret recipe for continents, one that made the very oldest rocks on Earth and is still making the island of Iceland today.

Along the way, we'll freeze a magma chamber solid, meet some politically contentious metals, and cross a real bridge from one tectonic plate to another.

Hi folks,

Thanks for your patience- it's been a busy month for me. The next episode will be up on December 4, followed by a more regular schedule for the following weeks. In the meantime, I've updated Episodes 25 and 26, streamlining them to better flow into the next episode.

This update also gives a brief explanation for why Bedrock has such large gaps. In short, the podcast is just one part of a busy academic and personal life, and there are times when it has to take a backseat.

Your continued support means so much...

What did the oldest rock look like 4 billion years ago, before it was pressure-cooked?

Today, we'll answer that question by melting chocolate chip ice cream, meeting one of granite's less famous cousins, and returning to our old friends: zircon crystals.

Extra credit: Eat some ice cream, go on a skiing trip, or both!

How old is the oldest rock, where was it found, and what type of rock is it?

To answer that question, we'll journey into Canada's Northwest Territories, deep underground to the breaking point of rocks, and we'll run into a shrimpy friend from Episode 10.

Welcome to Season 2 of Bedrock!

This episode introduces Season 2's subject: the Eoarchean (ee-oh-ar-key-an) chapter of Earth's history. The Eoarchean lasted from 4 to 3.6 billion years ago, from February 15 to March 19 on the Earth Calendar. In future episodes, we'll meet Earth's oldest rocks, the Man in the Moon, and a faint young sun.

Since this is our first big chapter break, we'll also learn how and why geologists split time into these chapters, including one of Canada's greatest scientists: Sir William E Logan.

Get caught up to speed on Season 1, a time known as The Hadean.

The Hadean covers Earth's earliest days from 4.6 to 4 billion years ago, January 1 to Feb 14 on the Earth Calendar. This is a time of many firsts, including the formation of the Earth, Moon, oceans, islands, and perhaps life.

Check out previous episodes for more details, like the women who mapped the Earth's inner core (6) and seafloor (11), the largest object to strike our planet (8), and our earliest ancestor (23).

Season 1 Finale.

What was the first living thing on Earth, when did it live, and what did it do?

Today, we end Season 1 by meeting LUCA, the oldest ancestor for every living thing on Earth today. On the way, we'll tackle how complex life formed in a chaotic universe and why it hasn't formed again, take a trip down life's family tree, and meet a deadly modern microbe- one of the closest relatives of the oldest living thing.

Thank you all for listening to Season 1, and stay tuned for Season 2!

Extra...

How and where did the first cells form on planet Earth, 4 billion years ago?

To answer that question, we investigate why oil and water hate each other, explore the seafloor with the Titanic's discoverer, and take a relaxing dip inside a hot spring.

Extra credit: drop some olive oil into water, or make a trip to the closest hot spring in your local area.

When did DNA show up in Earth's past, and how does it actually work today?

In this episode, we brush up on biology, learning about DNA's hardworking but underrated sister RNA, how cells turn genetic code into meat, and inch closer to actual living things in the Hadean.

Extra Credit: Help someone make a tasty dish in the kitchen today, or thank someone you think doesn't get enough credit for their work.

How did the Earth transform simple carbon into the complex ingredients of life?

Today, we'll meet a troubled Charles Darwin hunting for fossils, we'll create slime from thin air in one of the greatest laboratory experiments, and we'll learn what was in Earth's earliest atmosphere.

Extra Credit: Breathe in, breathe out, and have a sip of your favorite soup.

How did the ingredients of life arrive on Earth?

Today, we look at how asteroids brought organic material from the depths of space to Earth's surface. On the way, we'll run into an old friend from Episode 4, meet an ancient Greek astronomer, and search for aliens hidden in Antarctic ice.

Extra credit: Eat something with glutamic acid in it- meat, mushrooms, or soy sauce. Extra extra credit if you can have all three at once.

How were life’s ingredients assembled billions of years ago?

Today, we journey to the deepest reaches of space to take the first steps from non-living molecules to life. On the way, we learn what it really means to be organic, how to break a rainbow, and what space smells like.

Extra credit: Separate light using a prism, or cook a steak.

When did life begin on planet Earth?

That's a big question to tackle, one that will take a few episodes to answer. Today, we start this new arc by introducing three key ingredients of life: proteins, carbohydrates, and fats. These three molecules can be found in the food we eat, our own bodies, and as we'll see in future episodes, in the voids between stars.

Extra credit: Keep tabs on which foods you eat have more carbs, proteins, or fats. Make yourself a dish that has all three ingredients.

Miniseries Episode 7:

The oldest rocks on Earth are hidden deep in the Canadian North, 4 billion years old. For our final stop of our tour, we sneak a peek at these and other rocks we'll meet soon in the main series, including reefs made from bacteria and mysterious stones hidden beneath Greenland's glaciers.