43: Postcards From the Edge

Hello, and welcome to Bedrock, a podcast on Earth's earliest history. I'm your host, Dylan Wilmeth. Episode 43 Postcards from the Edge. Since episode 36, we've been investigating the oldest rocks in Greenland. These ancient stones are 3.9 to 3.6 billion years old. On our imaginary Earth calendar, that's February 23rd to March 19th. They're not Earth's oldest rocks, but geologists consider them the first major glimpse onto our planet's early days for two reasons. One.

the greenland rocks are more well preserved than older spots and two they cover a much larger area three thousand kilometers squared larger than rhode island larger than luxembourg This area is called the Itzhak complex. The best way to think about Itzhak is to imagine a thin vertical banner hanging on the wall, a patchwork quilt of stone stretching from the ceiling to the floor.

Most of the patches are made from dull, gray tonalite, a cousin of granite that tells us how islands became continents. Scattered throughout this gray tonalite tapestry are much smaller splashes of color, black, green, and red. These areas are windows onto the ancient sea floor. preserving dark lava flows, rusty iron, and maybe evidence for life. For the past three episodes, we've studied just one of these technicolor windows, a small corner...

of a small island named Achillea at the very bottom of the banner. After much deliberation, most scientists think this island is one of the oldest patches of the Great Greenland Tapestry. Achillea is Earth's oldest surviving slice of seafloor, or at least the most well-studied of these early, early patches. with iron and lava erupting deep beneath the ancient waves. Life was almost certainly around, but the evidence remains inconclusive. Our next destination...

is the opposite of Achillea in many ways. While Achillea sits at the bottom of the Great Greenland Banner, floating in the ocean, our new destination is at the banner's top border. far to the north, on the edge of titanic ice sheets. In terms of size, the Achillea rocks from the last three episodes could all fit inside a large sports stadium. A quick five-minute jaunt. Today's location is much wider, spread across 35 kilometers, or 22 miles. It also has the most...

pristine rocks we've yet seen, the greenest pastures for finding fossils. In other words, these new rocks are bigger and better than anything we've seen so far. is the final destination of Season 2. Today, I'll give an overview of this new Greenland location, a roadmap so we can divide and conquer in future episodes. The youngest rocks in this area will bring us right to the season's end. I truly have saved the best for last. Let's dive in. Part 1

The Age Lab. It's summer, 1971. A helicopter flies north over the great Greenland landscape, over snow-capped mountains, Plunging into blue fjords. There are no roads out here. Only natural highways of sea and air. In front of the helicopter, the northern horizon is swallowed. by a solid wall of glacial ice slowly getting closer and more detailed. Two men sit inside the copter, looking down at the landscape below.

it's hard to talk over the propeller's roar but they can still point out interesting layers and peaks to each other they're on their way to examine an iron mine at the edge of greenland's ice sheet the younger man is taller, clean-shaven, and a very familiar face to us. This is Vic McGregor, the New Zealand geologist who opened Greenland's oldest rocks to the world. He's been our constant companion since episode 36, and even by 1971, he's already spent years exploring the Greenland wilderness.

sitting across from vic is a shorter balding man with a dark goatee his name is stephen morebath and he's flown all the way from oxford england to visit vic and his rocks We briefly met Morbeth in episode 37, but he deserves a more proper introduction here. Morbath was born in 1929 in Magdeburg, Germany. His original name was Stefan Erwin Mosbach. The Mosbach family was Jewish.

but young Stefan attended a Catholic convent for education after the Nazis forbade Jews to attend public schools. The nuns protected Stefan when his father Heinz was taken away to Buchenwald. one of the Nazi's largest concentration camps. Miraculously, Heinz bribed his way out of the camp, likely due to a shiny military cross awarded as a World War I veteran. Young Stefan and his father Heinz were able to secure passage to the United Kingdom, but his mother Elsa was not as fortunate.

World War II made it impossible for her to cross the sea. She wrote letters to her family, but eventually perished in the Theresienstadt ghetto. In 1942, alongside 33,000 other souls. After all this hardship, Stefan was only 13 years old. In the UK... He now had the extra hardship of being a German living in a country at war with his homeland.

He would receive taunts and jeers from his fellow classmates, and his father, Heinz, was briefly held in a British internment camp, despite no wrongdoing. Stefan, now Stephen, was sent to a family in Oxford, England. Burying himself in schoolwork, he found a love and talent for chemistry, but hit a new roadblock. Money.

He needed funds to finish his high school, so he worked as a lab technician for Oxford's biochemistry department. This was not your everyday lab. Stephen was working for the folks who developed penicillin. many of whom would receive knighthoods and Nobel Prizes. Stephen was inspired, but still needed to finish schooling. Once a week, Stephen was allowed to attend evening classes.

chipping away for three years until he finally got his high school degree at 19. If you're a student with a job or three on the side, you're not alone out there. Fortunately, Stephen's story improves from here. Oxford University became his permanent home, first as a student eating cheap Indian food and joining ghost hunting clubs, then as a distinguished professor.

In 1956, his broad interest in chemistry focused into geochronology, the study of dating rocks. Not taking them out for a nice dinner, but figuring out their... ages. It was researchers like Morbath who helped nail down a solid timeline of Earth's ancient past. If you want to learn more about that subject, check out Episode 3, The Dating Game.

The one-sentence summary is that uranium decays to lead at a known rate, just like the ticking of a clock. Morbath became an expert in reading these clocks, their hiccups and quirks. He called his new laboratory the Age Lab and began to date rocks around Scotland. Some were among the oldest known at the time, 2.7 billion years old, May on the Earth calendar. Morbath was beginning to reach back into the truly ancient past, and his skill was getting noticed around the world, including Greenland.

In episode 36, we met Vic McGregor roaming around Greenland's capital of Nuke, unraveling a Gordian knot of old rocks. Vic hypothesized that the stones might be really old, but needed proof. In episode 37, Vic sent his rocks to Stephen Morbath's age lab in Oxford. Morbath... was happy to measure the ages, but he didn't think that they would amount to much. He promised his grad student, Lance Black, a bottle of wine for every Greenland sample older than three billion years.

That's how confident he was that the Greenland Rocks were young. When all was said and done, Morbath owed his student eight bottles of wine, but it was a happy donation. McGregor... was right. These were the oldest rocks on earth, at least at the time. This was the beginning of a powerful relationship. Vic McGregor knew the ancient Greenland landscape like the back of his hand. Stephen Moorbath could figure out how old those rocks were. It was a perfect team of space...

and time. A few months after Moorbath measured MacGregor samples, the two men finally met in person to explore a new Greenland location. Which brings us back to the choppa. Morbath had been through hell, but now he was heading to the top of the world.

Part two, the ice limit. Greenland has no highways. The world's largest island, the size of Mexico or Saudi Arabia, has only 150 kilometers or 90 miles of road and less than half of those are paved for reference the smallest u.s state of rhode island has 21,000 kilometers or 13,000 miles of road. Greenland is a vast but remote land. Most of Greenland's roads are found in and around

the coastal capital of Nuke, but they don't connect you to anywhere else. To reach nearby settlements and islands, you must either take a boat, or if you're really inspired, take a hike. That's exactly how Vic McGregor started his mapping, hiking and boating around the nuke capital. The town had under 10,000 folks at the time,

but was still a welcome sight to return to after a few days in the field. Vic's first batch of rocks, the one he sent to Stephen Moorbath, were clustered around the Nuuk shoreline, but he knew there was much more to discover. Using our banner analogy, Vic was studying the frayed bottom of the banner, but wanted to journey farther up, farther north. In 1971... He got a lucky break. The only folks with the money and infrastructure to place roots in Greenland's harsh interior were mining companies.

A few adventurers had found a large deposit of iron ore, 100 kilometers northeast of Nuke, on the edge of the Greenland ice sheet, the top of our imaginary banner. They knew about Vic's expertise and his recent success with Stephen Morbath. They were willing to fly these two geologists to their iron mine to see what they had. Now when I say this mine was at the glacier's edge, I mean nearly swallowed by the glaciers. Imagine standing on top of a mountain.

In one direction, you see a land of rolling tundra hills and large, silty lakes. Turn in the other direction, and you'll see a flat plain of ice extending to the horizon and tumbling down the mountainsides like frozen... waterfalls. This area is called Isua. That's I-S-U-A Isua. At least that's what it's called now. There were some mislabeled maps, some miscommunications. The real Isua is actually a few miles away. Even for a name nerd like me, it's too much. The name Isua has stuck.

in the scientific lingo, and we're going to use it here. Accidental or not, it's a fitting name. In Greenlandic, issue means the edge, just like the edge of these glaciers. McGregor and Moorbath touched down in their helicopter and set to work. Immediately, Vic was excited. The rocks here looked extremely similar to his first forays around Greenland's capital. with one major exception. These new rocks were in much better condition. To paraphrase a letter to a colleague,

It would not surprise me at all if at least some of these Isua rocks proved to be equivalent to the Nuuk area. One rock in particular stood out. one you might have already guessed based on context clues. The reason McGregor and Moorbath were visiting Issua was thanks to an iron mine. Say it with me now, this rock was... A banded iron formation, or BIF. Now we've seen plenty of BIFs before. They were once dark seafloors where iron rained down from waters above. We saw BIFs in Canada.

episode 32, and elsewhere in Greenland, episode 41. But they were far too small to place mines on. The fact that the industry was willing to dig for iron in Isiwa A hundred miles from the coast, next to giant glaciers with no roads in or out, should hopefully tell you we're in the big leagues now. But the biff was just the beginning.

As McGregor and Moorbath looked further, they saw other types of rocks. Common today, but ones we have not yet seen on the show. Household names like sandstones and limestones. the two geologists collected their rocks thanked the mine and headed home back in oxford it was moorbath's turn to shine he measured the ages of his newly collected issuer rocks and found that mcgregor

once again, was right. The Ischua samples were around 3.7 billion years old, around the same age as Vic's first samples from the capital. I can't stress how huge this discovery was. McGregor and Moorbath's team had already described the oldest rocks in the world around Greenland's capital. Now? They found rocks of similar age 100 kilometers away, indicating a huge area of very ancient stone. Even better, these issuer rocks were in much better shape

and preserved evidence for ancient sediments and sea floors. If there was anywhere to find Earth's oldest fossils, or Earth's oldest anything, it was here, on the edge of the ice. Just two years later, the mining company decided the distance and logistics were too much and closed down their iron operations in Isua. But...

They had opened a fresh mine of information, one that scientists are still visiting today. If industry would not fund future expeditions, it was now up to research grants to pave the way. The race to Greenland was on. Part 3. Return of the Shrimp International teams of geologists have explored the Isua region for over 50 years, creating increasingly accurate maps from field sketches to digital atlases. For this last segment...

We're going to make our own mental map of Ishua to get a lay of the land for future episodes. If you want to see real maps, check out our website, bedrockpodcast.com. There's a link. in the description. I want you to imagine the letter U made from stone. Okay, have that burned into your brain? Good. Now, imagine that this U... is stamped onto the Greenland tundra. Each side of the U, left, right, and bottom, is roughly 12 kilometers, or seven miles long.

around a quarter marathon to run for each leg. This is a much, much larger scale than most locations we've seen before. Let's start where we left off, the old iron mine. that McGregor and Moorbath examined. This mime sits in the upper right corner of that U, the end of the road. As we travel down this right arm, we're walking along...

the glacier's edge, ice to the east, rocks to the west. Here, we will see rocks that formed in the ocean's shallow end, much closer to the beach. Until now, we've only seen the deep...

dark seafloor. It will be good to see a new habitat. We will also witness a fresh debate about potential fossils, and not just microscopic flux of carbon, but weird lumps you can see with your own two eyes as we curve down to the bottom of the ewe we pull away from the ice and on to the open tundra here we must cross a huge lake over a mile wide to reach the other side of the U. The ancient rocks are still there, they're just hidden deep under lake water.

When we land on the other side, we begin up the left arm of the U. The rocks here are spread out much wider, giving us plenty of space to explore. On this left side of the U, we will return to a question I left open-ended in episode 39. How were the first continents built? We will also see even more fossil debates for you paleo nerds out there. Let's zoom back out to our bird's eye view of Yeshua, the giant U-shape spread around the Greenland landscape.

We begin with our usual question, how old are these rocks? To answer that question, let's return to Stephen Moorbath's lab in Oxford. Early dates measured from Isua were around 3.8 billion years old, March 3rd on the Earth calendar. However, as important as these dates were, there was a slight issue. On this show, I give you broad dates like 3.8 billion or 3.76 billion if I want to be ultra precise. However, there's always some imprecision.

when dating a rock, some wiggle room for error. Scientific journals make these imprecisions very clear. For example, Morbath reported his date as 3.76 billion give or take 70 million years. You might be saying, whoa, give or take 70 million? That doesn't seem very precise. Some of you might even be saying, Aha! I knew this whole age-dating process was a scam. The Earth can't possibly be billions of years old. Or perhaps you're perfectly fine with these numbers. In any case...

Let me put my straw man aside and work through these digits. An era range of 70 million years is a long time, but consider the main age. $3.76 billion. Without turning this into a number soup, the error bar here is a measly 2%. Imagine you pick up a bucket of candy. That says around 100 pieces inside. Maybe it's 98, maybe it's 102. In either case, you're basically getting what you pay for. That's the margin of error in Morbath's original papers.

For 1972, the simple fact that it was over 3 billion years old was good enough. As more research was done, the age estimates only grew more precise. By the 80s, the air bars had been shaved down to just 2 million years. Again, 2 million years is an unfathomable amount of time for humans to imagine. But... Considering these ancient Greenland rocks, that's less than a .05% error. In our candy analog, that's just an extra grain of sugar in the bag. Part of this innovation.

is thanks to a man and a machine we met way back in episode 10, and briefly again in episode 25. The man is Bill Compton at the Australian National University in Canberra. The machine is called the sensitive high-resolution ion microprobe. But we know it better as the shrimp. In short, the shrimp can get an age date from just a fraction of a crystal, instead of grinding down an entire rock like Morbath used to do. Far more dates can be gleaned from far...

less material. The Bill Compton and his shrimp gave us dates for the oldest material on earth in episode 10, and the oldest rocks on earth in episode 25. Comston also did the first shrimp analyses of Isua in the 1980s, but he won't play a major role in future Greenland episodes. It's just nice to see an old face return, even if briefly.

Instead, another researcher would take the wheel, a man we've spent a lot more time with recently, Alan Nutman. Nutman was the first major player we met on Achillea Island, episodes 40 to 42. He will also play a major role in the Isua story, so it's fitting that we start with him again. in nineteen ninety six nutman and his team published a landmark paper gathering rock ages from around southwest greenland this was the very same paper

That started all those Achillea debates back in episode 40. As a reminder, the Nutman crew said Achillea Island was nearly 3.9 billion years old, February 25th. on the calendar. So what about Isua, our new stomping grounds? These rocks are younger than Achillea Island. We're moving the story forward from February 25th to March 3rd on the calendar, a solid 3.8 billion years ago. We're finally in a new month. But wait, there's more.

teamed up and realized there was a pattern to the ages in Isua, which brings us back to our mental map. When you're ready, imagine that giant yew of stone spread across the tundra. Got it? Good. Here's what Team Nutman found. Everything below the U was older. March 3rd, 3.8 billion years old. All the rocks above the U, cradled like soup in a bowl, were younger. March 11th, 3.7 billion years old. Here's an even simpler analogy.

Imagine a smile made of stone. The lower lip is older rock. The upper lip is younger. And the teeth in between are, well, in between. As with everything in Greenland, this idea was debated. According to Nuttman, one reviewer called his paper, quote-unquote, a stream of geodiarrhea. which is unnecessarily harsh and just plain gross. But as more rocks are dated, this idea has become more accepted.

For the next few episodes, we will use this timeline to explore the ancient rocks of Isua. Physically, we will move from south to north, crossing this giant U of Stone. In time, we will amble forward from 3.8 to 3.7 billion years ago, a week of the Earth calendar. We will see the birth of islands. volcanic eruptions, completely new types of rock, and even more features that may or may not be fossils. Welcome to Isua, our best and biggest playground yet.

Summary In the world of ancient geology, the name Isua is often mentioned with a level of respect or even awe. It is an incredibly tough place to reach, 100 kilometers north of Greenland's capital with no roads in between. The massive Greenland ice sheet perpetually looms on the horizon. a relatively new feature guarding much much much older rocks below these rocks are the most extensive and well preserved of their age

Over 50 years of research, they have changed how we think about the early Earth, its continents, its oceans, and its life. This episode is just the appetizer. Over the next few weeks, we will dig into a buffet of stories. We'll start with the oldest rocks in the region south, 3.8 billion years old. Then we'll work our way forward in time to the youngest rocks in the north,

3.7 billion. This early week of the Earth calendar, March 3rd to 11th, will give us a real glimpse of what's to come, and will conclude Season 2. I'm incredibly excited. to tell you all about it let's go thank you for listening to bedrock if you like what you've heard today please take a second to donate using the link in the description

Every dollar helps make this show possible, and keep your eyes open for a Patreon coming soon. If that doesn't work, just tell a friend, rate the show, or leave a comment. It always makes my day, and that one person... Could be you. You can drop me a line at bedrock.mailbox at gmail.com. See you next time, and rock on!