Fault Lines

Every week, two geology obsessives pick apart a single moment that changed everything about this planet. The asteroid that killed the dinosaurs. The day oxygen poisoned the atmosphere. The snowball that froze Earth from pole to pole. Each episode reconstructs one turning point in deep time, walks through the competing scientific theories, and argues about what the evidence actually proves. Built for curious people who want to understand how Earth became the place we live on, with no geology degree required.

13 episodes

10d ago latest

weekly cadence

English language

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Episodes 14

The Core That Changed Its Mind
4d ago · 20:59
Fifty million years ago, during the Eocene, Earth was a warmer world with crocodiles near the poles and a magnetic field that was anything but calm. This episode asks whether the geological record of geomagnetic reversals is actually complete, or if entire flips of Earth’s magnetic field are missing from the story scientists tell. Along the way, the hosts examine ultra-slow reversals lasting up to 70,000 years, new evidence for uncounted reversals in Ethiopian basalts and statistical patterns after superchrons, and recent satellite data showing a surprising change in core flow beneath the Paci
The Day the Ground Broke the Sound Barrier
10d ago · 15:50
On March 28, 2025, a security camera outside Mandalay recorded the ground itself tearing sideways, 2.5 meters of slip along Myanmar's Sagaing fault in roughly two seconds, the same fault system born from the India-Eurasia collision some 50 million years ago. This episode asks whether fault rupture is governed by predictable physics or reconstructed after the fact through hindsight. Ola and Amara unpack the supershear "sonic boom" that outran the earthquake's own shear waves, its eerie parallel to the 1906 San Francisco quake, and a new stress study suggesting California's Mojave South segment
When the Permian Oceans Stopped Breathing
25d ago · 15:24
252 million years ago, Pangaea sat surrounded by a single vast ocean where tropical surface waters climbed past 38-40°C and oxygen levels collapsed, setting the stage for the Permian-Triassic extinction. This episode of Fault Lines puts a new study claiming to have "solved" the Great Dying on trial, asking whether one explanation can really account for a catastrophe that killed 96% of marine species and 70% of land animals. Ola and Amara work through the competing suspects, including Siberian Traps volcanism, hydrogen sulfide poisoning, and ocean acidification, then debate whether nine living
The Two Hours That Charbroiled Earth
1mo ago · 15:58
Four minutes after the Chicxulub asteroid struck the Yucatán roughly 66 million years ago, at the end of the Cretaceous period, the sky over the Gulf of Mexico turned white-hot as vaporized rock rained back down as glass spherules, triggering a global heat pulse. This episode asks what actually killed life across the planet in the hours, weeks, and months that followed. Ola and Amara examine a new Purdue-led study on fine dust from the Tanis site, weigh sulfur aerosols and Deccan Traps volcanism against a slower impact winter, and revisit the decades-old charcoal debate over global wildfires.
The Oddball Rock That Killed the Dinosaurs
1mo ago · 16:41
Around 66 million years ago, at the close of the Cretaceous period, a shallow sea covered the Yucatán Peninsula moments before an asteroid strike wiped out most life on Earth. This episode asks how scientists can identify the composition of an impactor that vaporized on contact, leaving no physical fragments behind. Ola and Amara walk through the nickel isotope technique used on K-Pg boundary clay, the identification of a rare CO chondrite from the outer solar system, and the resulting debate over whether sulfur emissions or fine silicate dust actually drove the extinction winter. Along the wa
The Zircons That Rewrote Earth's First Chapter
1mo ago · 15:29
Roughly four billion years ago, during the Hadean and early Archean, Earth's crust was a patchwork of newly stabilized blocks whose tectonic behavior remains debated among geochemists. Recorded live at Goldschmidt 2026 in Montréal, this episode asks whether plate tectonics began as one clean global shift or emerged unevenly across different regions and times. Ola and Amara compare zircon evidence from the Acasta Gneiss Complex and Saglek Block, review GEOTRACES isotope tracers used to reconstruct ancient seawater chemistry tied to snowball Earth and the Great Oxidation Event, and debate a new
The Last Animal Cambrian Forgot
2mo ago · 17:28
Amara opens with a cinematic tour of the 520-million-year-old Xiannüdong reef in Shaanxi, China, where hot Cambrian seas hosted nearly every major animal group — except one conspicuously absent group of filter-feeders. In this episode, we cover Scene-setting / cold open, Background / mystery setup, Core science / the discovery, and more.
When Our Ancestors Skipped the Tadpole
2mo ago · 20:25
Three hundred and nine million years ago, the land beneath modern Chicago was a swampy equatorial delta — oxygen at 35%, club mosses thirty meters tall, and dragonflies the size of hawks. The central question of this episode: did early four-legged vertebrates develop through amphibian-style metamorphosis, or did they hatch as miniature adults from the start? Ola and Amara examine the Pardo and Mann 2026 Science paper, which presents hatchling embolomere fossils from Mazon Creek with fully forming limbs and no external gills, then work through the fin-to-limb timeline from Tiktaalik to Romer's
The Rock That Built a World
2mo ago · 19:49
Sixty-six million years ago, in the Late Cretaceous, foraminifera-filled oceans teemed beneath skies that had never seen a mass extinction — until a 10-kilometer asteroid ended that world in seconds. This episode of Fault Lines asks whether the Chicxulub impact was purely a catastrophe, or whether it also structured what came next. Ola and Amara examine a June 2026 study in Communications Earth and Environment finding the Chicxulub crater sustained a hydrothermal system for at least 8 million years, a January 2026 study in Geology documenting new plankton species appearing fewer than 2,000 yea
The Volcano That Dimmed the Sun
2mo ago · 20:54
On June 15, 1991, the sky over Central Luzon turned white as Mount Pinatubo sent an ash column 40 kilometres into the stratosphere. The central question this episode tackles is whether the canonical 0.5 degrees Celsius of global cooling attributed to Pinatubo is actually reliable — and what is at stake if it is not. Ola and Amara trace the mechanism of stratospheric aerosol forcing from Pinatubo's 22-day global circumnavigation to the contested Toba supervolcano eruption of approximately 74,000 years ago, then scale further back to the Siberian Traps and Deccan Traps of the Permian and Cretace
When Earth Kept Freezing Itself Over and Over
2mo ago · 19:55
Seven hundred and seventeen million years ago, the equator was buried under sheets of ice in what geologists call the Sturtian glaciation, a freeze that lasted 56 million years. This episode asks a single question: was Snowball Earth a static, locked prison, or something far more dynamic? Ola and Amara examine two competing answers from the Cryogenian period (approximately 717 to 660 million years ago). The Southampton team's analysis of 2,600 varve layers from Scotland's Garvellach Islands reveals seasonal and solar cycles preserved inside Snowball rock, while Harvard's PNAS model proposes re
How the Ocean Stole Earth's Greenhouse
3mo ago · 19:26
Sixty-six million years ago, Earth was a greenhouse world with no polar ice, CO2 above 800 ppm, and palm trees growing in Alaska. This episode of Fault Lines asks why all that warmth slowly disappeared over the following 50 million years of the Cenozoic era. Ola and Amara examine a University of Southampton PNAS study finding that seawater calcium dropped by more than half across that period, walking through the foram proxy method used to reconstruct the record, debating whether calcium decline drove CO2 down or simply tracked alongside it, and weighing the Drake Passage and Antarctic Circumpo
When Volcanoes Ended the World
3mo ago · 18:28
On May 18, 1980, a magnitude-5.1 earthquake stripped the entire north face of Mount St. Helens in seconds, releasing the largest debris avalanche in recorded history. The episode asks whether the monitoring revolution that followed actually prepares us for the volcanic events capable of ending mass life on Earth. Ola and Amara move from the 4.2 cubic kilometers ejected at St. Helens up to the Siberian Traps' four million cubic kilometers of lava — the Large Igneous Province tied to the Permian-Triassic extinction event 252 million years ago — then work through the gas chemistry cascade and sil
The Day Earth Almost Died
3mo ago · 19:50
Two hundred and fifty-two million years ago, a biologically stable marine world built over fifty million years was erased in geological near-silence. This episode of Fault Lines examines the central question of the Permian-Triassic extinction: what actually killed 96% of marine species, and did anything that followed deserve to be called recovery? Ola and Amara walk through the Siberian Traps as the volcanic trigger, the cascading kill chain of thermal spikes, ocean anoxia, and acidification, and a January 2026 study in npj Biodiversity showing that Early Triassic ecosystems rebounded rapidly