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).

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Here's a new monthly podcast that Dylan's releasing on Patreon! Hometown Geology focuses on cities/locations around the world, chosen by patrons. This pilot episode highlights Dylan's current hometown of Grand Rapids, MI, home of gypsum mines, coal forests, and mastodon skeletons.

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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.

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P.S. Thanks to a bad cold, both my voice and the audio quality are not on par today.

P.P.S. The cold has also delayed Episode 51, which will be up later this week.

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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.

In this casual chat, Dylan talks about the show's growth, the upcoming end of Season 2, a potential career shift to science communication, and other podcast recommendations. Thank you all for bringing this show to 50 episodes- here's to 50 more!

Donate to support the show- anything is appreciated!

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.