Particles of Thought Fossil Hunting, Sinkholes, and Paleobotany with Kirk Johnson
Aug 26, 2025
Dr. Kirk Johnson, the Sant Director at the Smithsonian Institution's National Museum of Natural History and a paleo expert, dives deep into fossils and the ancient history of life on Earth. He shares fascinating insights about how fossils form, the origins of Earth's oceans, and his experience discovering fossil-rich sites worldwide. Kirk discusses the significance of the Burgess Shale, how asteroids may hold clues about early water, and reveals tips for aspiring fossil hunters. Join him for a journey through millions of years of Earth's history!
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Swamps And D-World Make Coal Seams
- Coal forms when trees accumulate in oxygen-poor swamps (D-world) where decay is inhibited and successive burial compacts plant matter into thick seams.
- Thick coal seams imply prolonged burial of vast plant piles, sometimes hundreds of feet before compaction.
Burgess Shale: A Flash-Frozen Cambrian Window
- The Burgess Shale is a Cambrian Lagerstätte where underwater slumps buried seafloor life and preserved soft anatomy in fine mud.
- Charles Doolittle Walcott discovered the site in 1909, revealing many previously unknown body plans.
Florida's Limestone Is Ancient Reef Memory
- Much of southern Florida and many cave systems are built on uplifted fossil coral limestone deposited ~35 million years ago.
- Rainwater dissolves limestone (carbonic acid), creating caves and the Swiss-cheese structure that leads to sinkholes.
