EarthDate

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EarthDate is a short-format weekly audio program delivering concise, science-based stories about the Earth: its geology, environments, and the processes that shape our planet over deep time and today. Beginning in 2026, EarthDate is managed by Switch Energy Alliance and hosted by SEA's founder Dr. Scott W. Tinker. Together, we explore earth systems, natural resources, and their relevance to everyday life, with a focus on clear, accessible science education for broad audiences. EarthDate is written and directed by Emmy-winning filmmaker Harry Lynch, and researched by Lynn Kistler. We search for captivating stories to remind listeners that science can enlighten, educate and entertain.

  1. 2H AGO

    Britain’s Stone Age Mines

    The gleaming White Cliffs of Dover have dark seams of flint within them that were the target of some of Britain’s first mines—more than six thousand years ago. The white cliffs are made of nearly pure chalk, the remains of phytoplankton, tiny floating algae. These phytoplankton lived here in warm Cretaceous seas. When they died, their spherical bodies fell apart into the hard plates that covered them. The microscopic plates, made of calcium carbonate, sank to the seafloor. There they formed a layer of white mud, at a rate of just half a millimeter per year. But over 30 million years, that white sediment layer reached nearly two thousand feet thick. Its weight compacted it into the chalk we see today. The main consumers of these floating algae were radiolarians, tiny zooplankton whose bodies were made not of calcium but silica. Once they died, and were compacted for millions of years, the silica in their remains formed layers of flint in the chalk. Though flint is a form of quartz, it’s nearly as hard as a diamond. It can be chipped to have very sharp edges, which Stone Age humans used to make blades and hunting points. It was so valuable that Neolithic tribes would dig mine shafts down through the soft chalk to reach a strip of flint, then bring it to the surface to work into tools. These mine shafts, and the tool making sites around them, may be Britain’s earliest industry and one of the reasons that human population grew here.

    2 min

  2. 2H AGO

    Dam Good

    Beavers are amazing rodents. They have long teeth that never stop growing; they control their length by gnawing on wood. They have fat-insulated bodies, webbed feet, and a large flat tail—which make them clumsy and exposed on land but quick and graceful in the water. Most importantly, beavers cut down trees to dam streams and rivers to make their homes. To many humans, these activities seem destructive. But the ponds and wetlands they create are essential for hundreds of other species that have coevolved with beavers over the last 10 million years. These include fish and insects, water birds, amphibians and reptiles, large grazing animals, and a multitude of plant species. Beaver ponds and wetlands provide food, water and shelter for many of these species—and create huge benefits for the forest: The ponds protect the woods from fires. Their surface water slowly drains into and recharges the water table. They filter out particulates to purify streams. They slow the progress of, and can even stop, floods. And serve as water repositories in times of drought. A century ago, trappers had hunted beavers nearly to extinction, for their furs. But around 1900, laws were enacted to protect them, and their population has since rebounded. Thankfully, beavers now occupy nearly all of their previous range, shaping and improving the landscape from Canada all the way down to northern Mexico.

    2 min

  3. 2H AGO

    Invisible Forces Shape Waves

    When you watch waves crash on the beach, you’re seeing the visible end result of many invisible forces. Waves are formed near or very far from shore, usually by wind—the first invisible force. As wind blows over the sea, surface friction transfers its energy to the water. How fast, how far, and for how long the wind blows determines how much waves grow. When the wind stops blowing, the waves stop growing—but they don’t stop traveling. A wave is not actually water traveling but instead another invisible force: energy traveling through the water. When a wave passes, water molecules lurch forward then back, coming to rest in nearly the same place. But that movement transfers energy to the next water molecule...and so on. Uninterrupted, this wave energy can travel thousands of miles through open ocean, sometimes for more than a week, before finally reaching a shoreline. As the water grows shallower, another invisible force comes into play: friction against the ocean bottom, which slows the base of the wave. But the top of the wave keeps moving at its original speed, eventually crashing forward over the wave base. The shape of that wave break is determined by the unseen topography below it. In some places, deep undersea canyons channel and concentrate wave energy as it reaches shore, to form some of the largest waves in the world. Spectacular sights, formed out of sight.

    2 min

  4. 2H AGO

    Swelling Seas

    Since the peak of the last Ice Age, Earth’s ice has been melting, and sea level has risen nearly 400 feet! But only recently do we have the technology to carefully measure it. For the last 20 years, a network of satellites and nearly 4,000 robotic floats have been measuring temperature and surface elevation of the global oceans. They’ve found that the surface of the ocean has warmed an average of 1 degree Fahrenheit in that time, and average global sea level has risen 3.5 inches. While this is within the normal rate of sea level rise for the past 8,000 years, we can now better understand what’s happening: Warming seas have contributed to the melting of ice sheets in Antarctica and glaciers in Greenland. Their meltwater is responsible for about 2.3 inches of that sea level rise. But the other 1.2 inches comes from a property of water itself. Water expands as it warms because molecules bump up against each other more frequently, causing an increase in volume. Meaning that, as oceans have warmed, they’ve swollen in their basins and slowly crept onto the land. Oceans act as heat sinks to moderate global temperatures swings, and researchers estimate they have absorbed 90 percent of the warming that Earth has experienced over these past 20 years. As our planet and oceans continue to warm, there will be more sea level rise, not just from more meltwater, but further swelling of the sea.

    2 min

  5. 1D AGO

    Carlsbad Caverns

    Carlsbad Caverns National Park is a very rare place. Its main room is the largest cave chamber in North America, covering more than eight acres. And its cave formations are unsurpassed anywhere. It’s also rare because it was created not by carbonic acid percolating down through the soil but by sulfuric acid coming up from below. Around 20 million years ago, hydrogen sulfide gas began to migrate underground from oil deposits in the Permian Basin of Texas, toward the exposed fossilized reefs near what is now Carlsbad, New Mexico. There, the hydrogen sulfide gas rose to meet the water table. It combined with oxygen to create sulfuric acid and began to dissolve the limestone that forms the Permian reef. Over the ages, as the water table rose and fell, the sulfuric acid worked on shallower and deeper layers, creating hundreds of caverns, some thousands of feet below ground. Around a million years ago, erosion connected the caves to the surface. Mineral-enriched water began to trickle in and, drop by drop, over millennia, formed spectacular crystal formations of calcite, aragonite, and gypsum. Seven thousand five hundred years ago the area began to dry up and the cave formations stopped growing. But they’re preserved there today in all their glory—waiting for you to make the trip to Carlsbad Caverns, to see some of the most stunning geology in the world.

    2 min

  6. 1D AGO

    Dinosaurs Run Hot and Cold

    When dinosaurs were first discovered, scientists thought they must have been cold-blooded like the lizards they resembled. Later, they realized that some dinosaurs are related to modern birds—which have the highest metabolic rate in the animal kingdom. Could dinosaurs, too, have been warm-blooded? New research reveals the answer is: both. So-called “cold-blooded” creatures, or ectotherms, are confined mostly to mild climates. They’re more sedentary but require less food and oxygen to survive. Warm-blooded creatures, or endotherms, can thrive in and migrate to diverse climates—but expend much more energy to maintain constant body temperatures. All creatures take in oxygen, and new research shows that the waste products of processing that oxygen—different in warm- and cold-blooded animals—are durable enough to be found in fossils. Molecular analysis of dinosaur fossils suggests an evolutionary break, with cold-blooded, slow-moving herbivores, like Stegosaurus, on one branch, and warm-blooded, highly mobile predators, like Velociraptors, on another. Larger dinosaurs like Brontosaurus and Tyrannosaurus also had high metabolic rates, but not as high as the ravenous Velociraptors. These findings indicate that dinosaurs evolved different metabolisms and body temperatures for different environmental niches—just as today’s animals have.

    2 min

  7. 1D AGO

    The Measure of a Meter

    In the 1700’s, there was no standard of measurement. Every village had its own unit. By some estimates, there were 250,000 different units in France alone. This made commerce and mapmaking so difficult that the French government created a special bureau to standardize things. And they decided to create the meter—which they defined as one ten-millionth the distance from the equator to the North Pole. The problem was they had no way to measure that. So, they made a painstaking, seven-year-long survey of the exact distance between Dunkirk and Barcelona and used the latitudes of those two cities to calculate the distance from equator to pole—which took another year. They divided that appropriately, then cast a platinum bar of that exact length, to create the meter standard. Thirty copies were sent around the world as the basis for the metric system. The bureau created a system of prefixes to denote multiples and divisions of the meter. A thousand meters is a kilometer. One-thousandth of a meter is a millimeter. Modern computers, telescopes and microscopes have required ever larger, and smaller, increments—we’re now up to quettameters, which is a thousand times the diameter of the universe! As our scientific instruments get ever more capable, we’ll need more terms for an ever expanding, and shrinking, metric system.

    2 min

  8. 2D AGO

    Gateway to Hell

    There’s a place in Siberia that the locals call “The Gateway to Hell.” Technically, it’s a retrogressive thaw megaslump. In plain English, a crater melted into the permafrost. In fact, it’s the largest permafrost melt in the world. It began 60 years ago, when the Russians clear-cut a strip of Siberian forest. This exposed the soil to the summer sun, which began to melt a crater that’s now a half mile wide and 300 feet deep—and still growing. This is important for two reasons. First, the crater has exposed 650,000 years of previously hidden sediment. In winter, when the soil is frozen and stable, scientists can enter the crater to recover specimens of extinct animals and to study how cycles of forestation and changing climate have impacted the area over millennia. Second, in summer, when the permafrost is melting, scientists are able to measure the air above the crater. As the organic material thaws, it’s consumed by microbes, which produce CO2 and methane. The crater produces both of these greenhouse gases at twice the rate of the surrounding area. Forest fires have exposed other areas of Siberian soil to the sun. And summer temperatures are rising. Both are melting more permafrost. The Gateway to Hell provides scientists a laboratory to study that melting, to see how it may affect the local landscape, and global climate, in the future.

    2 min
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About

EarthDate is a short-format weekly audio program delivering concise, science-based stories about the Earth: its geology, environments, and the processes that shape our planet over deep time and today. Beginning in 2026, EarthDate is managed by Switch Energy Alliance and hosted by SEA's founder Dr. Scott W. Tinker. Together, we explore earth systems, natural resources, and their relevance to everyday life, with a focus on clear, accessible science education for broad audiences. EarthDate is written and directed by Emmy-winning filmmaker Harry Lynch, and researched by Lynn Kistler. We search for captivating stories to remind listeners that science can enlighten, educate and entertain.

Information

  • Creator
    Switch Energy Alliance
  • Years Active
    2K
  • Episodes
    300
  • Rating
    Clean
  • Copyright
    © Copyright 2026 EarthDate
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