1ST QUARTER 1 PLATE TECTONICS. sciencepptx

grade 10 lesson

1. Plate Tectonics The theory that the Earth’s outermost layer is fragmented into a dozen or more large and small plates that move relative to one another as they ride on top of hotter, more mobile material.

2. Lithosphere consists of crust and the upper portion of the mantle. the entire lithosphere of the Earth is broken into numerous segments called plates . LITHOSPHERE

3. The continental crust is thicker but less dense than the oceanic crust. Because of the difference in density, continental crust floats higher than the oceanic crust. TWO TYPES OF CRUST

4. A plate is a large, rigid slab of solid rock. Plates are formed from the lithosphere: the crust and the upper part of the mantle. The plates “float” on the slowly flowing asthenosphere: the lower part of the mantle. The plates include both the land and ocean floor.. WHAT ARE TECTONIC PLATES

5. There are seven relatively large plates and a number of smaller ones, including the Philippine plate. The plates move very slowly but constantly, and this movement is called tectonics; thus the theory of moving lithospheric plates is called plate tectonics.

6. There are seven relatively large plates and a number of smaller ones, including the Philippine plate. The plates move very slowly but constantly, and this movement is called tectonics; thus the theory of moving lithospheric plates is called plate tectonics.

7. Earth’s Plates

8. Seven Major Plates African Plate Antarctic Plate Eurasian Plate Indian- Australian Plate North American Plate South American Plate Pacific Plate

9. Seven Minor Plates Philippine Plate Juan De Fuca Pate Cocos Palate Nazca Plate Scotia Plate Arabian Plate Caribbean Plate

10. Plate boundaries are the lines at the edges of the different pieces of the lithosphere. Lithospheric plates are moving due to the convection current in the Earth’s interior. PLATE BOUNDARIES

11. The lithosphere is made up of the crust and upper part of the mantle. There are two types of crusts: the continental crust which is thicker but less dense, and the oceanic crust, which is thinner and denser. According to the Plate Tectonic Theory, the Earth’s lithosphere consists of the crust and upper mantle that move slowly and constantly over time. This movement causes the formation of plate boundaries namely: divergent, convergent, and transform fault boundaries.

12. (a) Divergent boundaries refer to plates that separate and move apart in opposite directions forming new lithosphere - the young seafloor. This either occurs at mid-ocean ridges (seafloor spreading) or at rifted continental margins (rift valley). (b) Convergent boundaries are formed when two plates move toward each other. The oceanic plate bends downward at the subduction zone. This occurs in two oceanic plates: convergent boundary and continental plate-oceanic plate convergent boundary. Oceanic plate sinks because it is denser than the continental plate. In the case of convergence of two oceanic plates, the older plate sinks. Whereas in the convergence of two continental plates, they collide and buckle up forming mountain ranges. No subduction occurs in this type of convergence. (c) Transform fault boundaries are plates sliding past or slipping past each other.

13. - is formed when two tectonic plates move apart from each other creating tension. Molten rocks called magma to rise from the Earth’s mantle to the surface. The Earth’s surface is cool enough to solidify the magma that rose, thus, creating new oceanic crust or seafloor. A divergent boundary is also known as a constructive boundary. DIVERGENT BOUNDARY

14. The mid-ocean ridge is formed by the divergence between oceanic plates while continental rift valley is formed between continental plates.

15. Rift valley can also be found at the bottom of the ocean where seafloor spreading occurs. Both the formation of mid-ocean ridge and rift valley had the occurrence of an earthquake. Examples are boundaries between South American plate and African plate, Pacific Plate and Nazca Plate, and North American Plate and Eurasian Plate.

16. Divergent boundaries occur along spreading centers where plates are moving apart and new crust is created by magma pushing up from the mantle. The Mid-Atlantic Ridge is a divergent boundary. Sea-floor spreading over the past 100 to 200 million years has caused the Atlantic Ocean to grow from a tiny inlet of water between the continents of Europe, Africa, and the Americas into the ocean that exists today.

17. Iceland is splitting along the Mid-Atlantic Ridge between the North American and Eurasian Plates, as North America moves westward relative to Eurasia. In East Africa, spreading processes have already torn Saudi Arabia away from the rest of the African continent, forming the Red Sea. The actively splitting African Plate and the Arabian Plate meet in what geologists call a triple junction, where the Red Sea meets the Gulf of Aden.

18. Convergent boundary is formed when two plates move toward each other. This boundary has three types: Oceanic plate -Continental plate boundary, Two Oceanic plates boundary, and Two Continental plates boundary. CONVERGENT BOUNDARY

19. In Oceanic-Continental plates boundary and two oceanic plates boundary, the oceanic plate bends downward into the mantle through the process called subduction. The leading edge of the subducted plate melts in the mantle and magma rises forming a continental volcanic arc in oceanic-continental plate boundary, which is parallel to the trench that is formed due to subduction.

20. The oceanic plate subducts under the continental plate because it has HIGHER densi ty.  

21. From the diagram, it is clear that this event gives rise to the formation of a volcanic arc near the edge of a continental leading plate. The reason for this is because the denser oceanic crust (Plate A) undergoes what we call subduction process or the bending of the crust towards the mantle. Since the mantle is hotter than the crust, the tendency is, the subducted crust melt forming magma. Addition of volatile material such as water will cause the magma to become less dense, hence allowing it to rise and reach the crust once again and causing volcanic activities on the continental leading plate

22. For the oceanic crust, one important geologic feature is formed, and that is the TRENCH . Also called SUBMARINE VALLEYS , ocean trenches are the deepest part of the ocean. One of the deepest is the Philippine trench with a depth of 10 540 meters.

23. One of the deepest is the Philippine trench with a depth of 10 540 meters. It is widely known that the Mariana Trench is the deepest trench on the planet. Others either forgot or did not know that there is an impressive trench located here in the Philippines. One of the unique features that can be found within the exclusive economic zone of the country is the Philippine Trench also known as Philippine Deep and Mindanao Trench. It is known to be the 4th deepest trench in the world. The Philippine Trench was formed due to subduction from west to east of the islands in the Philippines. Dated 8 to 9 million years ago, the convergence of the Eurasian plate over the Philippine plate resulted in intra-arc deformation, which started the formation of the trench. Volcanic activities resulting in the subduction process along Leyte 2.5 million years ago also

24. The oceanic Nazca Plate is being subducted under the continental part of the South American Plate .

25. The oceanic Nazca Plate is being subducted under the continental part of the South American Plate . Where is the Nazca Plate located? The Nazca Plate is located beneath the southern Pacific Ocean to the west of South America . The edge of the Nazca Plate forms a border with the South American Plate where the two plates collide. Parts of the Nazca Plate form the western borders of Ecuador, Chile, and Peru, while most of the plate is below the ocean.

26. The South American Plate is being lifted up, creating the Andes mountains . Strong, destructive earthquakes and rapid uplift of mountain ranges are common in this region .

27. The Andes mountains formed when the Nazca Plate and South American Plate collide.

28. These earthquakes are often accompanied by uplift of the land by as much as a few meters. Mount Saint Helens is along the subduction zone of the Juan de Fuca plate (an oceanic plate) and the North American plate (a continental plate ).

29. A small tectonic plate , referred to as the Juan de Fuca plate , is present north of the San Andreas Fault off the northern California-Oregon-Washington coastline .  … responsible for the Cascade chain of volcanoes , which includes Mount St. Helens . Why Juan De Fuca Plate important?

30. Mount St. Helens  is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. What is Mount St. Helens most famous for? Helens sparked the advances in cutting-edge volcano science and monitoring that exist today. Mount St. Helens turned out to be the ideal laboratory to study volcanic activity. The 1980 eruption was the first large explosive eruption studied by scientists and observers using modern volcanology.

31. While in two oceanic plates boundary, island volcanic chain is formed parallel to the trench. An earthquake occurs in both type of boundaries. Since the oceanic plate is destroyed at the convergent boundary, this boundary is also called a destructive boundary . Examples are boundaries between the Eurasian plate and the Philippine plate, Nazca Plate and South American Plate, and Pacific Plate and Australian Plate.

32. Oceanic-Oceanic Convergence When two oceanic plates converge, one is usually subducted under the other. An older oceanic plate is colder, therefore more dense and less buoyant , and will subduct under a younger, hotter, less dense, and more buoyant oceanic plate .

33. In the process, a trench is formed. The deepest trenches in the oceans are along oceanic-oceanic subduction zones (i.e., the Marianas Trench in the Pacific, which is deeper than Mt. Everest is high). Oceanic-Oceanic Convergence

34. Examples of oceanic-oceanic convergence are the arcuate chains of islands in the southwest Pacific, Japan, and the Aleutian Islands .

35. The Aleutian Islands , also called the Aleut Islands or Aleutic Islands and known before 1867 as the Catherine Archipelago, are a chain of 14 large volcanic islands and 55 smaller islands. Most of the Aleutian Islands belong to the U.S. state of Alaska , but some belong to the Russian federal subject of Kamchatka Krai .

36. Underwater earthquakes, especially the stronger ones, can generate TSUNAMIS . The Japanese term for “harbor wave,” tsunami is a series of ocean waves with very long wavelengths (typically hundreds of kilometers) caused by large-scale disturbances of the ocean .

37. The leading edge of the subducted plate will eventually reach the mantle causing it to melt and turn into magma. The molten material will rise to the surface creating a volcanic island arc parallel to the trench. Volcanic island arc is a chain of volcanoes position in an arc shape as seen in figure. Oceanic-Oceanic Convergence

38. A  volcanic arc  (also known as a  magmatic arc   ) is a belt of  volcanoes  formed above a  subducting  oceanic  tectonic plate , with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an  oceanic trench , with the arc located further from the subducting plate than the trench. 

39. With two continental plates converging, a compression zone is formed. Both plates collide and buckle up causing mountain ranges such as the Himalayas mountain ranges. There is no subduction, no trench, and no volcanoes formed in this type of convergent boundary .

40. When two continental plates converge, a collision zone is formed. Subduction ceases for this particular type of convergence because the continental rocks are relatively light and resist downward motion. Instead, the crust tends to buckle and be pushed upward or sideways . Continental-continental Convergence

41. About 40 to 50 million years ago, two large land masses, India and Eurasia, collided to begin the formation of the most visible product of plate tectonics - the Himalayas .

42. Since subduction is impossible between two colliding continental plates, pressure is released by pushing the crusts upward and forming the Himalayan peaks . Also, collision of continental plates is associated with shallow earthquake activities.

43. The Himalayas is  the highest mountain range in the world, and has 9 out of 10 of the world's highest peaks, including Mount Everest . These mountains, referred to as the Third Pole , are the source of some of Asia's major rivers and also help to regulate our planet's climate.

44. Transform fault boundary is formed when two plates are sliding past each other. It is also called the Strike-slip fault. Rocks that line the boundary split into pieces as the plates slip at each other. A crack is then formed creating an undersea canyon or linear fault valley. San Andreas Fault is an example of this. TRANSFORM FAULT BOUNDARY

45. The San Andreas Fault is one of the few transform faults exposed on land . It connects the East Pacific Rise, a divergent boundary to the south, with the Juan de Fuca Ridge, a divergent boundary to the north. Most earthquakes in California are caused by the accumulation and release of strain as the two plates slide past each other.