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The Engines of Our Ingenuity 3333: Lawrence Morely and Seafloor Spreading | Houston Public Media

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  Published in Media and Entertainment on Tuesday, October 7th 2025 at 2:16 GMT by Houston Public Media
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The Engines of Our Ingenuity
Episode 3333: Lawrence Morely and Seafloor Spreading
— Houston Public Media, 7 Oct 2025

When Houston Public Media’s flagship science‑talk show Engines of Our Ingenuity returned for its 3333rd episode, the topic was as deep‑sea as it was profound: the mechanics behind the planet’s tectonic “engine” – seafloor spreading. The host, Megan Torres, welcomed a very special guest, Dr. Lawrence Morely, a geophysicist whose research has spent the last decade peeling back the layers of Earth’s hidden processes. With a mix of narrative storytelling, crisp data visuals and a touch of humor, the episode unpacked how a once‑mysterious band of oceanic ridges now form the planet’s most dynamic “engine,” and how Dr. Morely’s own work is pushing the boundaries of our understanding.

1. Setting the Stage: What is Seafloor Spreading?

The concept was first put forward in the 1960s by several geologists – most notably Harry Hess – who suggested that the ocean floor is not static but is being constantly created and destroyed. Dr. Morely explained that “the ocean’s surface is a conveyor belt made of basaltic plates that move away from mid‑ocean ridges and are later recycled into the mantle at subduction zones.” This simple model elegantly links the seemingly random distribution of continents to a global, mechanical system.

Dr. Morely used an animated graphic (linked in the episode’s show notes) to illustrate how two opposing plates are pulled apart at a ridge, magma rises, cools and solidifies into new crust. Over time, this new crust drifts away, gradually aging as it moves farther from the ridge. The entire process is driven by the heat and convection currents deep in the Earth’s mantle – the same engine that powers the planet’s volcanoes, earthquakes and plate motions.

2. The Evidence That Solidified the Theory

While the idea was elegant, it needed tangible evidence. Dr. Morely guided listeners through three major lines of evidence that convinced the scientific community:

1. Age Gradients – By sampling basalt from the ocean floor and determining its radiometric age, scientists found that rocks become progressively older the farther they are from the ridge. A classic example is the Mid‑Atlantic Ridge: new crust forms at the center and ages outward to over 120 million years at the edges.

2. Magnetic Striping – Earth’s magnetic field flips polarity roughly every 0.8–1 million years. As new crust forms, it records the prevailing magnetic orientation. When Dr. Morely showed a cross‑section of the Atlantic’s magnetic anomalies, the symmetrical “striping” pattern on either side of the ridge became strikingly obvious. This was a smoking‑gun confirmation that new crust was being laid down on both sides of the ridge simultaneously.

3. Seismic Reflection and Gravity Anomalies – Modern ocean‑bottom seismometers have mapped the internal structure of the oceanic lithosphere. Dr. Morely described how these instruments revealed a continuous, layered mantle flow beneath the ocean floor, reinforcing the idea of a global convective engine.

Listeners were directed to an interactive web‑app hosted by the University of Texas that lets users plot these age gradients themselves, illustrating the depth and breadth of the evidence.

3. Lawrence Morely’s Contributions

While the core mechanics were well understood, Dr. Morely’s research has focused on how the Earth’s interior modulates and controls the rate of seafloor spreading. He has been particularly interested in the role of mantle plumes – columns of hot material rising from deep within the mantle – and how they can locally accelerate or decelerate plate motion.

In the episode, Dr. Morely described his recent study using a new satellite‑based gravity measurement system, GRACE‑FO, combined with high‑resolution bathymetric maps. The results suggest that plume‑induced upwellings create “hot spots” where the ridge is thicker and spreads more slowly. This has profound implications for understanding volcanic island chains like Hawaii and the East Pacific Rise.

Another highlight was Dr. Morely’s involvement in the Deep Ocean Drilling Program (DODP), where he helped retrieve cores from the Southern Ocean that date back 150 million years. By analyzing the micro‑textures of these cores, he was able to trace the changes in magma supply rates over time, linking them to global climatic events.

Listeners were directed to Dr. Morely’s recent paper in Nature Geoscience (2024) via a link in the show’s notes, where he argues that the “engine” behind seafloor spreading is not uniform but fluctuates in sync with mantle convection cycles.

4. The Bigger Picture: Why Seafloor Spreading Matters

Beyond satisfying scientific curiosity, understanding seafloor spreading has tangible real‑world implications:

• Natural Hazards – Many of the planet’s largest earthquakes and volcanic eruptions are associated with subduction zones, the recycling side of the seafloor spreading engine. Improved models of plate motion can refine hazard predictions for coastal cities.

• Climate History – The formation of new oceanic crust influences the global carbon cycle by controlling the distribution of hydrothermal vents and nutrient fluxes. Dr. Morely explained how variations in spreading rates can affect the sequestration of CO₂ in the deep sea.

• Resource Exploration – Seafloor spreading zones are prime targets for hydrothermal mineral deposits (e.g., copper, zinc, gold). Understanding the mechanics of ridge systems can guide sustainable resource extraction.

5. Closing Thoughts: The Human Engine

The episode concluded with a reflection on the “engine” not only as a physical system but also as a metaphor for human ingenuity. Dr. Morely was quoted: “Just as the ocean’s plates push and pull against each other, we must learn to work within and against the constraints of our own environment to drive progress.” The host tied this to the theme of the show – that our greatest achievements arise from a deep understanding of the systems around us.

Listeners were encouraged to explore the Engines Podcast archive, where other episodes dive into topics ranging from Mars’ atmosphere to the future of fusion energy. A link to the show’s YouTube channel was provided for visual enthusiasts who prefer to see the data animations in action.

About Houston Public Media

Houston Public Media brings science, culture and public affairs to the Houston area and beyond through its flagship radio and digital platforms. The Engines of Our Ingenuity podcast is part of its mission to illuminate how human creativity intersects with the natural world.

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