Sea Floor Spreading with Bill Nye

Summary

In this video, the groundbreaking discoveries of geologist Harry Hess during World War II are highlighted. Serving as a Navy reservist, Hess utilized a depth sounder on his transport ship, uncovering an unexpected mountainous ocean floor in the Pacific. His pivotal research on the Mid-Atlantic Ridge revealed that the ocean floor was spreading, with new crust forming as molten rock rose from the Earth's interior. This led to the understanding of seafloor spreading and subduction, explaining how Earth's crust is recycled, thus reshaping our comprehension of geological processes.

Takeaways

• 🌊 Harry Hess was a geology professor and a Navy reservist during World War II who contributed significantly to oceanography.
• 🚢 While commanding a transport ship in the Pacific, Hess used a depth sounder to explore the ocean floor.
• 🏔️ Hess discovered that the ocean floor is not flat but features mountains, canyons, and volcanic activity.
• 📏 Prior to Hess's findings, most scientists believed the ocean floor was a flat sediment surface.
• 📍 In 1953, oceanographers identified the Mid-Atlantic Ridge, a 12,000-kilometer-long mountain range beneath the Atlantic Ocean.
• 🔭 The Mid-Atlantic Ridge is significantly higher than the average seafloor, standing about 2,500 meters above it.
• 🧪 Hess analyzed core samples and sonar readings around the Mid-Atlantic Ridge to draw his conclusions about the ocean floor.
• 🔄 He proposed the theory of seafloor spreading, where new crust is formed at the ridge from molten rock.
• 🌍 Hess found that the age of the ocean floor increases with distance from the Mid-Atlantic Ridge, indicating movement.
• ♻️ The process of subduction, where crust is recycled back into the Earth, balances the creation of new crust, preventing the Earth from growing larger.

Q & A

What role did Harry Hess play during World War II?

Harry Hess was a geology professor at Princeton University and also a Navy reservist. He served as the commander of an attack transport ship in the Pacific.

What significant discovery did Hess make while using a depth sounder?

Hess discovered that the ocean floor was not flat and sediment-lined as previously thought, but rather featured mountains, deep canyons, and trenches, including what were believed to be ancient volcanoes.

What was the Mid-Atlantic Ridge, and why was it important?

The Mid-Atlantic Ridge is a 12,000 km long mountain range discovered in 1953. It is significant because it is a ridge of underwater volcanoes that rises significantly above the surrounding seafloor.

How does the depth of the Mid-Atlantic Ridge compare to the average seafloor?

The Mid-Atlantic Ridge sits at about 2,500 meters deep, which is approximately 1.5 kilometers higher than the average seafloor depth of 4,000 to 5,000 meters.

What was Hess's conclusion about the age of the ocean floor?

Hess concluded that the ocean floor was progressively older the further it was from the Mid-Atlantic Ridge, indicating a process of seafloor spreading.

What is seafloor spreading, according to Hess?

Seafloor spreading is the process where molten rock is pushed up from inside the Earth at the Mid-Atlantic Ridge, forming new crust as it moves away on either side.

What does the term 'subduction' refer to in geological processes?

Subduction is the process where oceanic crust is recycled back into the Earth, occurring at convergent boundaries where one tectonic plate moves under another.

Why does the Earth not grow larger despite the generation of new crust?

Hess understood that while new crust is generated in some areas, it must be consumed or recycled in others, maintaining the Earth's overall size.

What was the broader implication of Hess's discoveries for geology?

Hess's discoveries contributed to the understanding of plate tectonics, showing that the Earth's surface is dynamic and constantly changing through processes like seafloor spreading and subduction.

What does this video suggest about the significance of oceanographic surveys?

The video highlights that oceanographic surveys, such as those conducted in the Atlantic, have led to major geological discoveries that reshaped our understanding of the Earth's structure and processes.