The Changing Faces of Earth 7A Rina.pptx

The Earth’s outer layer, called the crust, is not one solid piece. It’s actually made up of large pieces called plates. These plates are like giant puzzle pieces that cover the Earth, and they include all the land and oceans1.
These plates are constantly moving, but very slowly - about as fast as your fingernails grow1. They move because they’re sitting on top of a weaker layer of partially melted rock1.
There are three main ways these plates interact at their edges or boundaries:
They can slide alongside each other1.
They can crash into each other. When this happens, one plate might go under another and be destroyed, or they might push up and form mountains1.
They can move apart. When they do this, melted rock from beneath the plates rises up, cools, and forms new crust1.
This movement of the plates is also why we have earthquakes and volcanoes, which often happen along the plate boundaries1.

1. The Changing Faces of Earth By: Ann Maria , Ramsha , Rina

2. Learning Outcomes:- Theory of Plate Tectonics Earthquakes

3. Theory of Tectonics Tectonic plates, large slabs of rock that divide Earth's crust, move constantly to reshape the Earth's landscape. The system of ideas behind plate tectonics theory suggests that  Earth's outer shell (lithosphere) is divided into several plates that glide over the Earth's rocky inner layer above the soft core (mantle) .

4. THEORY: The Earth’s outer layer, called the  crust , is not one solid piece. It’s actually made up of large pieces called  plates .  These plates are like giant puzzle pieces that cover the Earth, and they include all the land and oceans 1 . These plates are constantly moving, but very slowly - about as fast as your fingernails grow 1 .  They move because they’re sitting on top of a weaker layer of partially melted rock 1 . There are three main ways these plates interact at their edges or boundaries: They can slide alongside each other 1 . They can crash into each other.  When this happens, one plate might go under another and be destroyed, or they might push up and form mountains 1 . They can move apart.  When they do this, melted rock from beneath the plates rises up, cools, and forms new crust 1 . This movement of the plates is also why we have earthquakes and volcanoes, which often happen along the plate boundaries 1 .

5. Earthquake : An  earthquake  is what happens when two blocks of the earth suddenly slip past one another. The surface where they slip is called the  fault  or fault plane. The location below the earth’s surface where the earthquake starts is called the  hypocenter , and the location directly above it on the surface of the earth is called the  epicenter . Sometimes, the energy released from the earthquake can be so strong that it can shake the ground and everything on it, like buildings and cars. This can sometimes cause damage.

6. Factopia : The Land of Truth Did you Know? A  seismograph  is a tool that scientists use to record earthquakes and measure their strength . It’s like a doctor’s stethoscope, but instead of listening to your heartbeat, it listens to the Earth’s heartbeat! It was invented by Sir James Alfred Ewing, Thomas Gray, and John Milne

7. Test Your Knowledge What is an earthquake? What causes an earthquake? What is a seismograph and what does it do?