1. Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
2. ❖ A tectonic plate, also called lithospheric plate, is a massive, irregularly shaped slab of
solid rock, generally composed of both continental and oceanic lithosphere.
❖ Plate size can vary greatly, from a few hundred to thousands of kilometers across.
❖ Pacific and Antarctic Plates are among the largest. Plate thickness also varies greatly,
ranging from less than 15 km for young oceanic lithosphere to about 200 km or more for
ancient continental lithosphere. For example, the interior parts of North and South
America.
What is a Tectonic Plate?
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
3. ➢ The Earth’s crust is divided into 12 major plates which are moved in various directions.
➢ This plate motion causes them to collide, pull apart, or scrape against each other.
➢ Each type of interaction causes a characteristic set of Earth structures or “tectonic”
features.
➢ The word, tectonic, refers to the deformation of the crust as a consequence of plate
interaction.
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
4. Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
5. ✓
✓
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
6. Causes of Plate Tectonics
• Convection Current is the driving force of plate tectonics in which hot, plastic-like material from the mantle
rises to the lithosphere, moves horizontally, cools, and sinks back to the mantle.
• The convection currents provide enough energy to move the plates in the lithosphere.
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
7. Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
8. Alfred Wegener
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
9. Evidence for Continental Drift
• Continental shape
• Similar geology
• Fossil evidence (animal and plant)
• Volcano and earthquake zone
• Paleomagnetism
• Hotspot tracking
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
10. • Matching coastlines on different continents:
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
11. • Matching mountain ranges across continents:
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
12. • Glacial ages and climate evidence:
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
13. • Fossil Evidence:
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
14. • Pattern of worldwide earthquakes (left) matches plate boundaries (right)
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
15. • Hotspot tracking
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
16. ❖The 3 types of plate boundaries:
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
17. ➢ Divergent Boundaries are the boundaries between two plates that are diverging, or
moving away from each other.
➢ The Mid-Atlantic Ridge is a divergent plate boundary where sea floor spreading occurs.
➢ Iceland sits atop a divergent plate boundary where continental rifting occurs
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
18. Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
19. Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
20. Convergent Boundaries
• Convergent Boundaries are the boundaries between two plates that are
converging, or moving towards each other.
• There are three types of convergent boundaries:
1. An ocean floor plate collides with a less dense continental plate.
2. An ocean floor plate collides with another ocean floor plate.
3. A continental plate collides with another continental plate.
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
21. Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
22. Transform Fault Boundaries
• Transform Boundaries are the boundaries between two plates that are
sliding horizontally past one another.
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
23. Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
24. Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
25. Effects of Plate Tectonics
• Landforms caused by plate tectonics:
a. Rift valleys (divergent boundaries)
b. Mountain ranges (continental-continental convergent boundaries)
c. Volcanoes (oceanic-continental convergent boundaries)
d. Faults (transform boundaries)
Md. Yousuf Gazi, Lecturer, Department of Geology, University of Dhaka (yousuf.geo@du.ac.bd)
