1.1 Internal Structure of the Earth.pptx

The structure of the earth is divided into four major components: the crust, the mantle, the outer core, and the inner core. Each layer has a unique chemical composition, physical state, and can impact life on Earth's surface.

1. Internal Structure of Earth Lesson 1

2. Objective/s: At the end of the lesson the learners will be able to: Gain conceptual understanding of the internal structure and processes of Earth Illustrate the composition of Earth using various materials.

3. Some Facts About Earth Earth is the only planet to be named in English. The word ‘Earth’ is Old English word for "land“ Earth belongs to the Milky Way Galaxy, Local Group Cluster and Virgo Super Cluster Earth is the only planet to sustain life Earth is believed to be exists for 450 million years & evidences are from 225 million years

4. Some Facts About Earth Earth is the third planet from the sun Earth is the fifth largest planet in the solar syste m The distance of the earth from the sun is 150 million km The diameter of the sun is 109 times the diameter of the earth The mass of the earth is 5.97 x 10 24 kg The Surface area of the earth is 510.1 million km²

5. Some Facts About Earth Before 500 BC, people thought that earth was flat. But thanks to scientists like Aristotle and Pythagoras, people know that the shape of the earth is spherical. However, Sir Isaac Newton showed that the earth was not a perfect sphere, but a compressed spheroid. The correct technical term to use will be oblate spheroid, a type of ellipsoid solid formed when an ellipse is rotated about its minor axis. The study of the size and shape of the earth is called geodesy The diameter of the earth at the poles is 12,714 km (minor axis). The diameter of the earth at the equator is 12,756 km (major axis).

6. What really is inside Earth? The structure of the Earth can be defined mechanically or chemically. RHEOLOGY – the study of the flow of matter primarily in the liquid state under conditions at which they respond with the plastic flow rather than deforming elastically in response to an applied force.

7. What really is inside Earth? Mechanically, Earth can be divided into five layers; lithosphere asthenosphere mesospheric mantle Outer core inner core Chemically, the layers of the Earth are: crust upper mantle lower mantle outer core inner core

8. Lithosphere This is the outer solid part of the planet including the Earth's crust as well as the underlying cool, dense, and rigid upper part of the upper mantle. It extends from the surface of the earth to a depth of about 70-100 km.

9. Asthenosphere The asthenosphere is that part of the layer of earth which is below the Lithosphere. It extends at a depth of 100 km to 400 km from the lithosphere. Due to the high temperature, this region is partially molten. Here the velocity of seismic wave slowdowns abruptly. This region is called the Low-velocity region . Also, it is rich in Peridotite. Moreover, this region is popularly known as the Magma Chamber .

10. Crust It is the uppermost and the thinnest layer of the earth. The average thickness of the crust is about 35 km.

11. Continental Crust (SIAL layer) In terms of structure, composition, density, and thickness, the continental crust differs from the oceanic crust. It is composed of granitic and andesitic rocks. The continental crust is rich in Feldspar minerals. Moreover, the density of the continental crust is about 2.6gm/cm 3 . The average thickness is about 40km. However, in the mountainous regions, the thickness reaches up to 100 Km.

12. Oceanic Crust (SIMA layer) The oceanic crust is made up of Basalt. It is rich in ferro-magnesia. Its density is about 3 g/cm 3 . The Conrad discontinuity divides the continental crust and the oceanic crust. Mohorovicic discontinuity The Moho discontinuity separates the crust and mantle. It was discovered by a Croatian seismologist Andrija Mohorovicic in 1909, who inferred that the velocity of seismic waves is related to the density of the material that is moving through.

13. Mantle The mantle extends from the base of the crust at a depth of 2900km. It comprises about 80% of the earth’s total volume. Mantle contain Iron, magnesium and calcium. Because of increasing temperature and pressure inside the earth, it is hotter and denser than the crust. This steady increase of temperature is called geothermal gradient , which is believed to be the one responsible for different rock behaviors within the mantle.

14. Upper Mantle It comprises of Peridotite and Gabbro and Plagioclase minerals. The average density of the upper mantle is about 4.5 g/cm 3 . The average temperature of this layer is about 1100 C ⁰. The Repetti Discontinuity separates the upper mantle from the lower mantle. Due to Repetti discontinuity , there is a sharp increase in the velocity of the seismic waves. The upper mantle is heterogeneous in terms of density and composition. The thickness of the uppermost part of this stratum is about 80-100 km. The uppermost part of the upper mantle is as rigid as the crust. Both crust and upper mantle constitute the Lithosphere.

15. Lower Mantle The lower mantle extends at a depth of 670 km to 2900km. The average density of this region is about 6.5g/cm 3 . It is composed of Olivine, Plagioclase, and Orthoclase minerals. Guttenberg Discontinuity separates the lower mantle and the upper core of the earth.

16. Core At the depth of 2900 km to 6371 km, lies the core of the earth. Because of its metallic composition, its density is nearly twice of the mantle. It comprises 15% to 16% of the total volume of the earth. The core is divided into two regions called the outer core and the inner core.

17. Outer Core It extends between 2900 km to 5150 km. The density of the outer core is about 10g/cm 3 . It mainly consists of Iron and Nickle (about 85%). The outer core is always in the molten state. Lehman Discontinuity separates the outer core and the inner-core.

18. Inner Core The inner core extends between 5150 km to 6371 km. The average density of the inner core is about 13g/cm 3 . Despite the high temperature, the inner core is always in a solid state due to very high pressure prevailing in this region. The temperature of the inner core is about 6000 C⁰.

19. Interior of the Earth

20. Discontinuities on the layers of Earth