The earth’s interior

Interior's of the Earth

1. The Earth’s Interior Module 2: By: Derrick Martin Igay

2. Scientist have studied heavenly bodies which are millions of miles away from Earth. Equipped with powerful telescopes and probes, they were able to reach and examine the solar system and beyond. this module will help you visualize and understand the composition and structure of the Earth’s Interior. Also it will help you to describe different layers of the Earth as well as understand their characteristics. I. Introduction

3. In this module, you should be able to: Describe the internal structure of the Earth. Discuss the possible causes of plate movement. Enumerate the lines of evidence that support plate movement. II. Learning Objectives

4. The Earth is made up of three layers: the crust, the mantle, and the core. The study of these layers mostly done in the Earth’s crust since mechanical probes are impossible due to the tremendous heat and very high pressure underneath the Earth’s surface Studying the Earth’s Interior

5. Are waves of energy that travel through the layers of the Earth and are results of earthquakes, volcanic eruptions, magma movement, large landslide and large man-made explosions that give out low frequency acoustic energy. S eismic W aves

6. Surface Waves Travels across the surface. Surface waves decay more slowly with distance than body Waves, which travel in three dimensions . Body Waves Travel through the interior of the Earth along paths controlled the material properties in terms density and modulus. Two types of Seismic waves:

7. P wave (Primary wave)- is a pulse energy that travels quickly through the Earth and through liquids. The P wave travel faster than S wave . S wave (Secondary wave or shear wave)- is a pulse energy that travels slower than P-wave through P and S waves

8. Activity 1 Procedure: Using the given organizer, write the necessary information to complete the concept about seismic wave. Seismic waves Definiton Main types Sub-types Sub-types

9. The Earth’s composition tells a story about itself. It gives us clues to its past and proofs about the gradual and slow changes that is has undergone for over 4.6 billion years. The Composition of the Earth’s Interior

10. The crust is the thinnest and the outermost layer of the Earth that extends from surface to about 32 km below. T he continental crust is mainly made up of silicon, oxygen, aluminum, calcium, sodium and potassium. Continental crust, found under land masses, is made of less dense rocks such as granite. The oceanic crust is around 7-10 kilometers thick with average thickness is 8 kilometers. It is found under the ocean floor and made of dense rocks such as basalt. The oceanic crust is heavier than the continental crust. The Crust

11. Beneath the crust is the mantle, which extends to about 2900 kilometers from the Earth’s surface. It makes up 80% of the Earth’s total volume and about 68% of its total mass. The mantle is mainly made up of silicate rocks and contrary to common belief. The mantle is mostly made of elements silicon, oxygen, iron, and magnesium. The lower part of the mantle consist of more iron than the upper part. The Mantle

12. The core is subdivided into two layers: the inner and the outer core. It is 2250 kilometers thick and is made up of iron and nickel. The outer core is mainly made up of iron and nickel moving around the solid inner core, creating Earth’s magnetism. The Core

13. Aside from the fact that the Earth has a magnetic field and that it must be iron or other materials which are magnetic in nature. The inner core must have a density that is about 14 times that of water. Average crustal rocks with densities 2.8 times that of water could not have the density calculated for the core. So iron, which is three times denser than crustal rocks, meets the required density. What tells us that the inner core is made up of iron?

14. Some clues that the inner core and the outer core are made up of iron include the following: Iron and nickel are both dense and magnetic. The overall density of the earth is much higher than the density of the rock in the crust. This suggest that the inside must be made up of something denser than rocks. Meteorite analysis have revealed that the most common type is chondrite . The whole earth and the meteorite roughly have the same density, thus the Earth’s mantle rock and meteorite minus its iron, have the same density.

15. The Continental Drift The Earth’s Mechanism In 1912, Alfred Wegener, a German meteorologist, proposed a theory that about 200 million years ago, the continents were once one large land mass. He called this landmass Pangaea, a G r eek word which means “All Earth”. This Pangaea started to break into two smaller supercontinent called Laurasia and Gondwanaland during the Jurassic Period.

16. Wegener search for evidences to support his claim. He noticed the fit of the edges of the continents on the opposite sides of the South Atlantic. His evidences to the continental drift theory includes the distribution of fossils in different continents, rock features, and ancient climates.

17. The most visible and fascinating evidence that these continents were once one is their shapes. The edge of one continent surprisingly matches the edge of another: South Africa, Australia, India, and Antarctica, and Australia match one another: Eurasia and North America complete the whole continental puzzle in the north. Evidence: The Continental Jigsaw Puzzle

18. Fossils are preserved remains or traces of organisms (plants and animals) from the remote past. Fossilized leavens of an extinct plant Glossopteris were found in 250 million years old rocks. These fossils were located in the continents of Southern Africa, Australia, India, and Antarctica, which are now separated from each other by wide oceans. The large seeds of this plant could not possibly travel a long journey by the wind or survive a rough ride through ocean waves. Evidence from Fossils

19. Fossils found in rocks support the Continental Drift Theory. The rocks themselves also provide evidence that continents drifted apart from each other Coral Deposits Evidence from rocks Coal beds were formed from the compaction and decomposition of swamp plants that lived million years ago. These were discovered in South America, Africa, etc.

20. During the 1950’s and 1960’s, new techniques and modern gadgets enable scientist to make better observations and gather new information about the ocean floor. In the early 1960’s, scientist Harry Hess, together with Robert Dietz, suggested an explanation to the continental drift. This is the seafloor spreading theory. Overtime, the new oceanic crust pushed the old oceanic crust far from the ridge. The process of seafloor spreading allowed the creation of new bodies of water. The Seafloor Spreading

21. In the place where two oceanic plates collide or when an oceanic plate and a continental plate collide, a subduction zone occurs. As the new seafloor is formed at the mid-ocean ridge, the old sea floor farthest from the ridge is destroyed at the subduction zone.

22. The rate of formation of a new new seafloor is not always as fast as the destruction of the old seafloor at the subduction zone. When the seafloor spreading is greater than the subduction , then the ocean gets wider.

23. Magnetic Reversal also called magnetic “flip” of the Earth. It happens when the North P ole is transformed into a S outh Pole and the South P ole becomes the N orth Pole. This is due to the change in the direction of flow in the outer core. The occurrence of magnetic reversals can be explained through the magnetic patterns in magnetic rocks, especially those found in the ocean floor. Magnetic reversal

24. Magnetic Reversal Magnetic Polarity Time Scale

25. The Plate tectonic Theory provided an explanation about the movement of the lithospheric plates. This theory evolved from the two former theories and was developed during the first decade of the 20 th century. There are three types o f plate movements– separation of two plates ( divergent ), collision of two plates ( convergent ) and sliding past each other ( transform ) Plate Tectonic Theory

26. As a substance like water is heated, the less dense particles rise while denser particles sink. This continuous process is called convection current. The convection currents rotate very slowly, as they move and drag the plates along. Because of convection current, the tectonic plates are able to move slowly along the tectonic boundaries. Convection Current