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The journey over the Mariana Trench is wild.
If the ocean water suddenly evaporated, your ship would fall a whopping 10.9 km. Even crazier is the geology in this region.
How did the Earth form such a steep and deep geometry here? Here is a surprising fact. About 200 km east of this deepest point, there is a chain of 15 islands perfectly parallel to the trench known as the Mariana Islands. On one side, a deep trench. On the other, a collection of islands. Now, can you guess how the Mariana Trench was formed?
Yes, you're right. The only possibility is the collision of two tectonic plates. Specifically, one highly dense plate colliding with a less dense one. Let's study this crucial process in detail.
Millions of years ago, the massive Pacific plate, which was moving westward, crashed into the smaller Mariana plate. When they collided, the Pacific plate was forced to bend and dive beneath the lighter, more buoyant Mariana plate. During this motion, you can see that the Mariana plate bends inward and travels downward, causing it to sink at a very steep angle. The Mariana Trench is the exact physical location of this collision. This process of one plate sinking under another is called subduction. It's the deep V-shaped scar on the ocean floor created as the Pacific plate bends and plunges down into the Earth's mantle. This is how the deepest trench on the planet was created.
Now, let's explore how the Mariana Islands were formed. As the Pacific plate sank, it dragged down seawater and waterlogged sediment. The plate plunged hundreds of kilometers into the hot mantle. The surprising thing is that while traveling into the mantle, the rock of the subducting plate melted much earlier than expected. The reason is the presence of trapped water and sediment in the rock. This reduced the melting temperature of the rock. This phenomenon is known as flux melting. This is very similar to how salt decreases the melting point of ice. This newly melted rock is now hotter and less dense than the surrounding material. So, it rises up and erupts onto the seafloor on the Mariana plate. Over millions of years, repeated eruptions of lava and ash built up a massive underwater mountain. When these eruptions are huge, the top of one of these underwater volcanoes finally breaks the ocean surface. This is how the Mariana Islands were formed, perfectly curved and parallel to the Mariana Trench.
At the southern end of the Mariana Trench, there is an unusually deep point, the Challenger Deep. Why is this region suddenly so deep compared to the other parts of the trench?
Scientists believe that at the southern end of the trench, the subducting plate actually tore. Because of this, this portion lost support from the remaining plate area. Without that side support, the torn portion is effectively in freef fall through the mantle. It is sinking vertically at a much steeper angle than normal subduction zones. This steep vertical drop creates a much deeper Vshape in the trench floor.
Now it's time to get into an exciting phase of the video. Human expeditions to the Mariana Trench's Challenger. Deep and the extreme technologies they used. The first expedition was in 1960 by Jacques Beicard and Lieutenant Don Walsh. They used an interesting vessel technology. It had a baisy scaff design. It had two main components, a huge buoyant float on top and a tiny cruise sphere below.
To achieve buoyancy, you can't used compressed air as it would be crushed. Instead, the Trieste used a massive 15 meter long thinwalled float filled with 320,000 gall of aviation gasoline. As gasoline is lighter than water, it provides the positive buoyancy needed to lift the craft. This vessel had a genius technique to keep the pressure of the gasoline the same as that of the surrounding seawater. As the vessel descended through this pipe, the engineers allowed the entry of seawater. Since water is denser, it will always settle at the bottom and of course it won't mix with the gasoline. The high pressure push from the water increased the pressure of the gasoline as well. Thus, throughout the journey, it was made sure that the ocean and the inside vessel pressure are the same. The next main part of this design is the sphere, the crew cabin. This was the only part of the vessel that had to truly resist the pressure. The sphere was in fact a fortress with 13 cm thick forged high strength steel. The internal diameter of the sphere was just 1.93 m. Barely enough room for two men to sit. To sink, the crew flooded the tanks and carried 9 tons of iron pellets held in two large hoppers by electromagnets.
The descent took 4 hours and 47 minutes.
The crew spent only 20 minutes on the bottom famously observing a flatfish. Marine biologists now doubt that this could be a sea cucumber. To go up, the pilot simply flipped a switch to cut power to the electromagnets. This released the iron pellets, and the craft, now positively buoyant from its gasoline float, would begin its slow rise to the surface. The ascent took 3 hours and 15 minutes.
The second was 52 years later by none other than James Cameron. He wanted to become the first solo man to reach the bottom of the Challenger Deep. This new vessel, the Deep Sea Challenger, was a complete rethink. It was designed to descend and descend rapidly, maximizing time on the bottom.
The Deep Sea Challenger was built around a new patented foam. This foam, which has incredible strength, occupied 70% of the sub's volume. Surprisingly, the same material helped the sub to float. It was lighter than water and even lighter than gasoline.
In fact, the researchers had to develop a new foam named Isofloat which could withstand the incredible pressure of Challenger Deep. Since all existing foams failed under this pressure, the foam wasn't just in the sub. It was the sub's main structure. This design also featured a sphere.
Because James Cameron was a solo pilot, the sphere could be much smaller. The system operated on the same ballast principle, but with modern technology. The sub carried a ballast weight of 450 kg of steel. The Trieste could only go up and down, but the Challenger had 12 powerful oil-filled electric thrusters for full 3D mobility on the seafloor. The descent took only 2 hours and 36 minutes.
If the ocean water suddenly evaporated, your ship would fall a whopping 10.9 km. Even crazier is the geology in this region.
How did the Earth form such a steep and deep geometry here? Here is a surprising fact. About 200 km east of this deepest point, there is a chain of 15 islands perfectly parallel to the trench known as the Mariana Islands. On one side, a deep trench. On the other, a collection of islands. Now, can you guess how the Mariana Trench was formed?
Yes, you're right. The only possibility is the collision of two tectonic plates. Specifically, one highly dense plate colliding with a less dense one. Let's study this crucial process in detail.
Millions of years ago, the massive Pacific plate, which was moving westward, crashed into the smaller Mariana plate. When they collided, the Pacific plate was forced to bend and dive beneath the lighter, more buoyant Mariana plate. During this motion, you can see that the Mariana plate bends inward and travels downward, causing it to sink at a very steep angle. The Mariana Trench is the exact physical location of this collision. This process of one plate sinking under another is called subduction. It's the deep V-shaped scar on the ocean floor created as the Pacific plate bends and plunges down into the Earth's mantle. This is how the deepest trench on the planet was created.
Now, let's explore how the Mariana Islands were formed. As the Pacific plate sank, it dragged down seawater and waterlogged sediment. The plate plunged hundreds of kilometers into the hot mantle. The surprising thing is that while traveling into the mantle, the rock of the subducting plate melted much earlier than expected. The reason is the presence of trapped water and sediment in the rock. This reduced the melting temperature of the rock. This phenomenon is known as flux melting. This is very similar to how salt decreases the melting point of ice. This newly melted rock is now hotter and less dense than the surrounding material. So, it rises up and erupts onto the seafloor on the Mariana plate. Over millions of years, repeated eruptions of lava and ash built up a massive underwater mountain. When these eruptions are huge, the top of one of these underwater volcanoes finally breaks the ocean surface. This is how the Mariana Islands were formed, perfectly curved and parallel to the Mariana Trench.
At the southern end of the Mariana Trench, there is an unusually deep point, the Challenger Deep. Why is this region suddenly so deep compared to the other parts of the trench?
Scientists believe that at the southern end of the trench, the subducting plate actually tore. Because of this, this portion lost support from the remaining plate area. Without that side support, the torn portion is effectively in freef fall through the mantle. It is sinking vertically at a much steeper angle than normal subduction zones. This steep vertical drop creates a much deeper Vshape in the trench floor.
Now it's time to get into an exciting phase of the video. Human expeditions to the Mariana Trench's Challenger. Deep and the extreme technologies they used. The first expedition was in 1960 by Jacques Beicard and Lieutenant Don Walsh. They used an interesting vessel technology. It had a baisy scaff design. It had two main components, a huge buoyant float on top and a tiny cruise sphere below.
To achieve buoyancy, you can't used compressed air as it would be crushed. Instead, the Trieste used a massive 15 meter long thinwalled float filled with 320,000 gall of aviation gasoline. As gasoline is lighter than water, it provides the positive buoyancy needed to lift the craft. This vessel had a genius technique to keep the pressure of the gasoline the same as that of the surrounding seawater. As the vessel descended through this pipe, the engineers allowed the entry of seawater. Since water is denser, it will always settle at the bottom and of course it won't mix with the gasoline. The high pressure push from the water increased the pressure of the gasoline as well. Thus, throughout the journey, it was made sure that the ocean and the inside vessel pressure are the same. The next main part of this design is the sphere, the crew cabin. This was the only part of the vessel that had to truly resist the pressure. The sphere was in fact a fortress with 13 cm thick forged high strength steel. The internal diameter of the sphere was just 1.93 m. Barely enough room for two men to sit. To sink, the crew flooded the tanks and carried 9 tons of iron pellets held in two large hoppers by electromagnets.
The descent took 4 hours and 47 minutes.
The crew spent only 20 minutes on the bottom famously observing a flatfish. Marine biologists now doubt that this could be a sea cucumber. To go up, the pilot simply flipped a switch to cut power to the electromagnets. This released the iron pellets, and the craft, now positively buoyant from its gasoline float, would begin its slow rise to the surface. The ascent took 3 hours and 15 minutes.
The second was 52 years later by none other than James Cameron. He wanted to become the first solo man to reach the bottom of the Challenger Deep. This new vessel, the Deep Sea Challenger, was a complete rethink. It was designed to descend and descend rapidly, maximizing time on the bottom.
The Deep Sea Challenger was built around a new patented foam. This foam, which has incredible strength, occupied 70% of the sub's volume. Surprisingly, the same material helped the sub to float. It was lighter than water and even lighter than gasoline.
In fact, the researchers had to develop a new foam named Isofloat which could withstand the incredible pressure of Challenger Deep. Since all existing foams failed under this pressure, the foam wasn't just in the sub. It was the sub's main structure. This design also featured a sphere.
Because James Cameron was a solo pilot, the sphere could be much smaller. The system operated on the same ballast principle, but with modern technology. The sub carried a ballast weight of 450 kg of steel. The Trieste could only go up and down, but the Challenger had 12 powerful oil-filled electric thrusters for full 3D mobility on the seafloor. The descent took only 2 hours and 36 minutes.
Cameron spent 3 hours on the bottom filming in 3D and trying to use a manipulator arm to collect samples. Did he actually use the manipulator arm? Well, that was a big letd down for the team despite a successful mission. The crushing pressure in the Mariana Trench damaged a hydraulic line. This hydraulic line was controlling a robotic manipulator arm which was meant to collect rocks. Cameron was not able to operate the arm and he couldn't collect rocks from the Mariana Trench.
The discovery of the Mariana Trench is astonishing. In 1875, the crew of HMS Challenger experienced a bottomless ocean. On March 23rd, 1875, the ship was sailing in the Western Pacific southwest of Guam. The crew stopped to conduct a routine sounding. This was a primitive method of measuring the depth by lowering a weighted rope into the ocean. As they lowered the rope, it kept going and going.
The weight finally hit the bottom after releasing a rope length of 8,184 m. The crew were astonished. They had just found the deepest point in the ocean known to man at that time. The trench remained mysterious for over 75 years.
In 1951, HMS Challenger 2 visited the site, this time with echo sounding technology. They recorded a depth of nearly 11,000 m. This is why the deepest point on Earth got that name as a tribute to HMS Challenger 2.
At the bottom of the Mariana Trench, the pressure is over 1,086 bar, almost 1,000 times the atmospheric pressure. This is like having an elephant stand on your thumb. No sunlight penetrates this deep. Moreover, the water is consistently just above freezing, typically 1° to 4°.
Life seems impossible in the Mariana Trench. Oh, did you see that? A strange looking fish inside the trench. This is a Mariana snail fish, the undisputed star of the trench and the deepest living fish ever discovered. These fishes have been swimming at a depth of 8,178 m.
The deepest point, Challenger Deep, is dominated by microbes and giant single-sellled amiebas called xenophores.
The Mariana snailfish we saw live in the hadal zone. The Mariana snailfish feed on tiny shrimplike crustaceians.
There are more interesting creatures in this zone. Have a look at the Dumbo octopus. The other interesting creatures in the trench are the giant amphipods and benthodon.
This image illustrates different creatures living in the Mariana Trench with depth.
You might wonder why these animals aren't instantly crushed. It's because of a simple reason. They are not hollow. An airfilled submarine or a human lung gets crushed because there is a massive difference between the low pressure inside and the high pressure outside. Deep sea creatures on the other hand are almost entirely made of water. Their bodies are at the same pressure inside and out. So there's no net force to crush them. This also means that these creatures do not have any gas- fil spaces like human lungs. Otherwise, they would be instantly compressed and collapse.
You might be wondering how these creatures are able to navigate without light. They rely heavily on senses other than sight. Many have highly developed lateral lines, organs that can sense tiny changes in water pressure and vibrations, allowing them to detect a predator or prey moving nearby.
To understand how deep the Mariana Trench is, consider this imaginary comparison. The height of Mount Everest is 8,849 m, the highest point on planet Earth. If you were to take Mount Everest and place it base first into the Challenger Deep, its summit would not even break the surface of the water. The peak of Everest would be more than 2 km below the water surface. There is a widespread speculation on the internet that the Mariana Trench is a treasure of rare earth minerals. But in reality, there is no significant deposit of rare earth minerals in the Mariana Trench that has been publicly identified for mining. The widespread discussion about deep sea rare earth minerals is often focused on other parts of the Pacific Ocean, mostly at depths of 4,000 to 6,000 m. For example, Minimator Island and Clarion Clipperton zone. Minimator Island is Japan's exclusive economic zone. A massive deposit of mud rich in rare earth elements has been confirmed here about the Clarion Clipperton zone. This vast expanse of the Pacific Ocean floor between Hawaii and Mexico is covered in poly metallic nodules. These potato-sized rocks are rich in manganese, nickel, cobalt, and copper and also contain rare earth elements. It should be noted that both the minimator island area and the Clarion Clipperton zone are still in the exploration, testing, and regulatory phases. Commercial scale mining is not yet underway at either location.
Scientists have solved a lot of mysteries around the Mariana Trench, but one mystery still remains. Is Mariana Trench acting as a water thief? Here's the mystery. Researchers from University of Washington and Stony Brook University studied the movement of the tectonic plates in detail. They mainly analyzed the hydrated rock which is sinking down to the mantle. Their study found that hydrated rock extends 32 km below the ocean floor. Their calculations proved that three times more water is penetrated into the mantle than previously thought. This water should somehow reach the ocean back. Sea levels have remained relatively stable for a significant amount of time. The only option for this is volcanic eruptions. Here's the issue. Studies show the water coming out of volcanic eruptions is much lower than the water swallowed by the mantle. Where does the remaining water go?
If you like to visualize how deep the Mariana Trench is, here is an interesting animation.
The discovery of the Mariana Trench is astonishing. In 1875, the crew of HMS Challenger experienced a bottomless ocean. On March 23rd, 1875, the ship was sailing in the Western Pacific southwest of Guam. The crew stopped to conduct a routine sounding. This was a primitive method of measuring the depth by lowering a weighted rope into the ocean. As they lowered the rope, it kept going and going.
The weight finally hit the bottom after releasing a rope length of 8,184 m. The crew were astonished. They had just found the deepest point in the ocean known to man at that time. The trench remained mysterious for over 75 years.
In 1951, HMS Challenger 2 visited the site, this time with echo sounding technology. They recorded a depth of nearly 11,000 m. This is why the deepest point on Earth got that name as a tribute to HMS Challenger 2.
At the bottom of the Mariana Trench, the pressure is over 1,086 bar, almost 1,000 times the atmospheric pressure. This is like having an elephant stand on your thumb. No sunlight penetrates this deep. Moreover, the water is consistently just above freezing, typically 1° to 4°.
Life seems impossible in the Mariana Trench. Oh, did you see that? A strange looking fish inside the trench. This is a Mariana snail fish, the undisputed star of the trench and the deepest living fish ever discovered. These fishes have been swimming at a depth of 8,178 m.
The deepest point, Challenger Deep, is dominated by microbes and giant single-sellled amiebas called xenophores.
The Mariana snailfish we saw live in the hadal zone. The Mariana snailfish feed on tiny shrimplike crustaceians.
There are more interesting creatures in this zone. Have a look at the Dumbo octopus. The other interesting creatures in the trench are the giant amphipods and benthodon.
This image illustrates different creatures living in the Mariana Trench with depth.
You might wonder why these animals aren't instantly crushed. It's because of a simple reason. They are not hollow. An airfilled submarine or a human lung gets crushed because there is a massive difference between the low pressure inside and the high pressure outside. Deep sea creatures on the other hand are almost entirely made of water. Their bodies are at the same pressure inside and out. So there's no net force to crush them. This also means that these creatures do not have any gas- fil spaces like human lungs. Otherwise, they would be instantly compressed and collapse.
You might be wondering how these creatures are able to navigate without light. They rely heavily on senses other than sight. Many have highly developed lateral lines, organs that can sense tiny changes in water pressure and vibrations, allowing them to detect a predator or prey moving nearby.
To understand how deep the Mariana Trench is, consider this imaginary comparison. The height of Mount Everest is 8,849 m, the highest point on planet Earth. If you were to take Mount Everest and place it base first into the Challenger Deep, its summit would not even break the surface of the water. The peak of Everest would be more than 2 km below the water surface. There is a widespread speculation on the internet that the Mariana Trench is a treasure of rare earth minerals. But in reality, there is no significant deposit of rare earth minerals in the Mariana Trench that has been publicly identified for mining. The widespread discussion about deep sea rare earth minerals is often focused on other parts of the Pacific Ocean, mostly at depths of 4,000 to 6,000 m. For example, Minimator Island and Clarion Clipperton zone. Minimator Island is Japan's exclusive economic zone. A massive deposit of mud rich in rare earth elements has been confirmed here about the Clarion Clipperton zone. This vast expanse of the Pacific Ocean floor between Hawaii and Mexico is covered in poly metallic nodules. These potato-sized rocks are rich in manganese, nickel, cobalt, and copper and also contain rare earth elements. It should be noted that both the minimator island area and the Clarion Clipperton zone are still in the exploration, testing, and regulatory phases. Commercial scale mining is not yet underway at either location.
Scientists have solved a lot of mysteries around the Mariana Trench, but one mystery still remains. Is Mariana Trench acting as a water thief? Here's the mystery. Researchers from University of Washington and Stony Brook University studied the movement of the tectonic plates in detail. They mainly analyzed the hydrated rock which is sinking down to the mantle. Their study found that hydrated rock extends 32 km below the ocean floor. Their calculations proved that three times more water is penetrated into the mantle than previously thought. This water should somehow reach the ocean back. Sea levels have remained relatively stable for a significant amount of time. The only option for this is volcanic eruptions. Here's the issue. Studies show the water coming out of volcanic eruptions is much lower than the water swallowed by the mantle. Where does the remaining water go?
If you like to visualize how deep the Mariana Trench is, here is an interesting animation.