SleepWise: Learn Softly, Sleep Deeply
Jul 23, 2026 · 1 hr 29 min · 10 segments
Drift into deep time with this calming bedtime story about the five great mass extinctions that reshaped life on Earth. Tonight, we journey across hundreds of millions of years, from the warm shallow…
Grandpa CohenHost
Tiny grains of volcanic ash settle across an ancient seabed and later become a clock.

their radioactive elements changing at a steady rate that allows scientists to estimate when the layer formed.

Elsewhere, a thin band of unusual metal, a sudden shift in carbon, or a change in the chemistry of fossil teeth.

Paleontologists compare which species occur below a boundary and which survive above it.

Shallow seas leave richer records than mountains or forests, where erosion may remove entire chapters.

If it disappears at nearly the same time from rocks on several continents, the signal becomes harder to dismiss.

Grains shaped by storms, minerals formed without oxygen, pollen from damaged forests, soot from fire or droplets of once molten rock thrown high into the atmosphere.

Layers of ash can be measured with radiometric techniques, while reversals in Earth's magnetic field and recurring changes in the planet's orbit help match distant sequences.

Tiny grains of volcanic ash settle across an ancient seabed and later become a clock.

their radioactive elements changing at a steady rate that allows scientists to estimate when the layer formed.

Elsewhere, a thin band of unusual metal, a sudden shift in carbon, or a change in the chemistry of fossil teeth.

Paleontologists compare which species occur below a boundary and which survive above it.

Shallow seas leave richer records than mountains or forests, where erosion may remove entire chapters.

If it disappears at nearly the same time from rocks on several continents, the signal becomes harder to dismiss.

Grains shaped by storms, minerals formed without oxygen, pollen from damaged forests, soot from fire or droplets of once molten rock thrown high into the atmosphere.

Layers of ash can be measured with radiometric techniques, while reversals in Earth's magnetic field and recurring changes in the planet's orbit help match distant sequences.
The rest of this transcript — segmented and speaker-labeled, so you land on the exact moment something was said
Search every transcript — by keyword, by phrase, or by meaning, across every show Radar indexes
Trends — what is surging across podcasts, measured against its own baseline
Alerts — when a name you follow appears in a newly indexed episode
No account is needed to search Radar.