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- Gold Foil Experiment
- Faraday Cage
- Oil Drop Experiment
- Magnetic Monopole
- Why Do Fireflies Light Up
- Types of Blood Cells With Their Structure, and Functions
- The Main Parts of a Plant With Their Functions
- Parts of a Flower With Their Structure and Functions
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- Why Does Ice Float on Water
- Why Does Oil Float on Water
- How Do Clouds Form
- What Causes Lightning
- How are Diamonds Made
- Types of Meteorites
- Types of Volcanoes
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Layers of The Earth
Earth is the fifth largest planet in our solar system, and the only one proven to support life. It has multiple layers, with each having distinct characteristic features. If we could slice the planet to half, we would see it is composed of multiple layers, arranged one above the other.
Why Does the Earth have Different Layers and How Are They Formed
According to a general conception, during its formation, the earth underwent a period of differentiation, with the heaviest elements sinking to the center and the lighter ones rising to the surface, thus causing the earth to develop layers as it cooled.The resulting chemical composition can define the earth’s internal layering. Scientists discovered the different layers of the earth based on the study of seismic waves that are generated by earthquakes and explosions that travel through the earth and across its surface.
How Many Layers Does the Earth Have, and What Are They Called
The earth’s internal structure is made up of three major layers: the crust, the mantle, and the core, The mantle and the core are further subdivided to form five distinct layers in total. Each of the layers involving the main layers has its own set of characteristics that are described below along with their chemical compositions, and physical or mechanical properties. The names of these layers, in order of their presence from the top, are as follows:
2. Upper Mantle
3. lower mantle, 4. outer core, 5. inner core, all the earth’s layers, their structure and composition.
Temperature: 475 K (∼200°C) at the surface to 1300 K (∼1000°C)
Thickness: 25 miles (32 km) for continental crust and 3-5 miles (8 km) for oceanic crust
Density : ∼ 2830 kg/m 3 at the continental crust and ∼ 3000 kg/m 3 at the oceanic crust
It is the outermost and thinnest layer of our planet and is least dense among all other layers. Based on its thickness and location, the crust is of two types, the continental crust that consists of granite rocks and found near the mountain ranges, and the oceanic crust that consists of basalt and found under the oceans. The most abundant elements found in the earth’s crust include oxygen, silicon, aluminum, iron, and calcium. The temperature within the earth’s crust is high enough to melt rocks and form the lower layer called the upper mantle.
Temperature: 1200 K (∼ 932°C) at the upper boundary with the crust to 1900 K (∼1652 °C) at the boundary with the lower mantle
Thickness: 255 miles (410 km)
Density : ∼ 3400 kg/m 3
It is the largest and thickest layer of earth. The upper mantle, along with the crust, makes up the lithosphere of earth, which is physically distinct from the layers lying below due to its low temperature high thickness. Below the lithosphere is found a much hotter and malleable portion of the upper mantle called the asthenosphere layer that begins at the bottom of the lithosphere and extends up to 450 miles (700 km) deep inside.The composition of the upper mantle is not found to be in a steady-state but always in constant motion. The upper mantle moves large areas of crust, called tectonic plates, resulting in the formation of volcanoes, mountains, or earthquakes. Between the upper and lower mantle, there is the presence of the transition zone, which ranges in depth from 250 – 410 miles (410 – 660 km).
Temperature: 1900 K (∼ 1600°C) in the outer regions which can reach up to 4300 K (∼4000°C) at the bottom
Thickness: 1,400 miles (2,250 km)
Density : ∼ 4400 kg/m 3
It is found below the upper mantle from a depth of about 400 miles (650 km) down to 1,800 miles (2,900 km) and is thus incredibly large and takes up most of the earth’s volume. Being so deep inside the earth, the temperature and pressure of the lower mantle are extremely high. Here in the lower mantle, the convection currents allow heat from the interior of the earth to rise to the surface.
Temperature : 4,300 K (4,030°C) in the outer regions to 6,000 K (5,730°C) closest to the inner core
Thickness: 1,355 miles (2,180 km)
Density : 9,900 – 12,200 kg/m 3
Found below the mantle and having a composition similar to the inner core with 80% iron, along with nickel and some other lighter elements. The outer core has a very high density and thus always found to exist in the viscous-liquid state due to not having enough pressure to be compressed to a solid.
Temperature: 5,700 K (∼5,500°C)
Thickness: 760 miles (∼1,220 km)
Density : 12,600 – 13,000 kg/m 3
It is the center, and the hottest part of the earth. Similar to the outer core, the inner core is composed primarily of iron and nickel and has the highest density among all other layers. The inner core is made mostly metals such as gold, platinum, palladium, silver, and tungsten. Due to extremely high temperature and pressure, the metals present in the inner core change their structural conformation and are found to exist in solid state. Recent discoveries also suggest that the solid inner core itself is composed of two layers, separated by a transition zone of about 150 – 250 miles (250 – 400 km) thickness.
Ans. The lithosphere includes the brittle upper portion of the mantle, and the crust or outer layer of the earth’s surface.
Ans. The lithosphere is the mechanical layer of the earth that contains the seven major plates, which include the African, Antarctic, Eurasian, North American, South American, India-Australian, and the Pacific plates.
Ans. Asthenosphere is the earth’s only layer that is mechanically weak and thus can be easily deformed.
- What are the Earth’s layers? – Phys.org
- Explainer: Earth — layer by layer – Sciencenewsforstudents.org
- What are the layers of the Earth? – Zmescience.com
- The Composition and Structure of Earth – Courses.lumenlearning.com
Article was last reviewed on Thursday, February 2, 2023
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5 responses to “Layers of The Earth”
Can someone explain to me how did the scientists come up with the conclusion about the thickness of each layer without going there or exploring it?
By measuring the time of travel of refracted and reflected seismic waves, scientists could infer the thickness of each layer of Earth.
This is really helpful
Very informational and helpful! I would definitely recommend.
this helped me a lot thanks guys
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Science News Explores
Explainer: earth — layer by layer.
Sizzling heat, unimaginable pressure and some surprise diamonds: It’s all there, deep beneath us
Scientists understand much about Earth’s structural layers — the inner core, core, mantle and crust. Yet there are still great mysteries to solve about our planet’s inner workings.
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By Beth Geiger
November 11, 2019 at 6:45 am
Mountain ranges tower to the sky. Oceans plummet to impossible depths. Earth’s surface is an amazing place to behold. Yet even the deepest canyon is but a tiny scratch on the planet. To really understand Earth, you need to travel 6,400 kilometers (3,977 miles) beneath our feet.
Starting at the center, Earth is composed of four distinct layers. They are, from deepest to shallowest, the inner core, the outer core, the mantle and the crust. Except for the crust, no one has ever explored these layers in person. In fact, the deepest humans have ever drilled is just over 12 kilometers (7.6 miles). And even that took 20 years!
Still, scientists know a great deal about Earth’s inner structure. They’ve plumbed it by studying how earthquake waves travel through the planet. The speed and behavior of these waves change as they encounter layers of different densities. Scientists — including Isaac Newton, three centuries ago — have also learned about the core and mantle from calculations of Earth’s total density, gravitational pull and magnetic field.
Here’s a primer on Earth’s layers, starting with a journey to the center of the planet.
The inner core
This solid metal ball has a radius of 1,220 kilometers (758 miles), or about three-quarters that of the moon. It’s located some 6,400 to 5,180 kilometers (4,000 to 3,220 miles) beneath Earth’s surface. Extremely dense, it’s made mostly of iron and nickel. The inner core spins a bit faster than the rest of the planet. It’s also intensely hot: Temperatures sizzle at 5,400° Celsius (9,800° Fahrenheit). That’s almost as hot as the surface of the sun. Pressures here are immense: well over 3 million times greater than on Earth’s surface. Some research suggests there may also be an inner, inner core. It would likely consist almost entirely of iron.
The outer core
This part of the core is also made from iron and nickel, just in liquid form. It sits some 5,180 to 2,880 kilometers (3,220 to 1,790 miles) below the surface. Heated largely by the radioactive decay of the elements uranium and thorium, this liquid churns in huge, turbulent currents. That motion generates electrical currents. They, in turn, generate Earth’s magnetic field. For reasons somehow related to the outer core, Earth’s magnetic field reverses about every 200,000 to 300,000 years. Scientists are still working to understand how that happens.
At close to 3,000 kilometers (1,865 miles) thick, this is Earth’s thickest layer. It starts a mere 30 kilometers (18.6 miles) beneath the surface. Made mostly of iron, magnesium and silicon, it is dense, hot and semi-solid (think caramel candy). Like the layer below it, this one also circulates. It just does so far more slowly.
Explainer: How heat moves
Near its upper edges, somewhere between about 100 and 200 kilometers (62 to 124 miles) underground, the mantle’s temperature reaches the melting point of rock. Indeed, it forms a layer of partially melted rock known as the asthenosphere (As-THEEN-oh-sfeer). Geologists believe this weak, hot, slippery part of the mantle is what Earth’s tectonic plates ride upon and slide across.
Diamonds are tiny pieces of the mantle we can actually touch. Most form at depths above 200 kilometers (124 miles). But rare “super-deep” diamonds may have formed as far down as 700 kilometers (435 miles) below the surface. These crystals are then brought to the surface in volcanic rock known as kimberlite.
The mantle’s outermost zone is relatively cool and rigid. It behaves more like the crust above it. Together, this uppermost part of the mantle layer and the crust are known as the lithosphere.
Earth’s crust is like the shell of a hard-boiled egg. It is extremely thin, cold and brittle compared to what lies below it. The crust is made of relatively light elements, especially silica, aluminum and oxygen. It’s also highly variable in its thickness. Under the oceans (and Hawaiian Islands), it may be as little as 5 kilometers (3.1 miles) thick. Beneath the continents, the crust may be 30 to 70 kilometers (18.6 to 43.5 miles) thick.
Along with the upper zone of the mantle, the crust is broken into big pieces, like a gigantic jigsaw puzzle. These are known as tectonic plates . These move slowly — at just 3 to 5 centimeters (1.2 to 2 inches) per year. What drives the motion of tectonic plates is still not fully understood. It may be related to heat-driven convection currents in the mantle below. Some scientists think it’s caused by the tug from slabs of crust of different densities, something called “slab pull.” In time, these plates will converge, pull apart or slide past each other. Those actions cause most earthquakes and volcanoes. It’s a slow ride, but it makes for exciting times here on Earth’s surface.
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