Changes to Earth’s Surface Chapter 6

Prior Knowledge What are the layers of the Earth? What causes Earth’s surface to change? What causes earthquakes? Describe a volcano and how it erupts.

Lesson 1 How Does Earth’s Surface Change?

Layers of the Earth Crust (0-100 km thick) The thin outer layer of Earth, including dry land and the ocean floor. This is the thinnest and least dense layer. The crust is thick under continents and thinner under oceans.

Layers of the Earth Mantle - The thick layer of the Earth beneath the crust Upper part is rigid, like Earth’s crust. Underneath it is a thick zone of hot, soft rock.

Layers of the Mantle Lithosphere - (1.6-130 km thick) is the crust and the stiff upper part of the mantle Moho - The Mohorovicic Discontinuity is the boundary between the crust and the mantle, where seismic waves change velocity. Asthenosphere (72-250 km thick) is the lower part of the mantle which is made up of iron and magnesium silicate minerals. This layer is said to have plasticity because it is hot, soft and can flow.

Layers of the Earth Core - The layer of Earth extending from the Earth’s center to the bottom of the mantle. It is mostly iron and nickel. Outer core (2200km thick) is made of very hot liquid iron and nickel. The movement of the outer core produces Earth’s magnetic field. Inner core (1250km thick) is very hot but the pressure from the layers around it make it into a solid metal ball.

Wind, Water, & Gravity Change Earth’s Surface Weathering - The process by which rock is broken down into smaller pieces. Erosion - The removal of transportation of weathered materials. Gravity - is a powerful tool that causes erosion.

Wind, Water, & Gravity Change Earth’s Surface Sediments - small pieces of rock that are weathered and eroded and carried by wind and water. Deposition - is the dropping or settling of eroded material and occurs very close to where sediment was originally produced.

9. How do wind, water and gravity change Earth’s surface? They weather, erode and deposit materials.

Ice Changes Earth’s Surface Glaciers- A large sheet of moving ice that stays frozen year around. 11. What are the 3 ways that glaciers can chance the landscape? Glaciers can carve out areas of Earth’s surface. Deposit large piles of sediment. Can cause the land to uplift when glaciers retreat.

Impacts Change Earth’s Surface 12. Meteorites- rocks from space 13. What causes Craters to form? Meteorite impacts cause craters to form.

6-2 What Are Plates and How Do They Move? 1. Plate Tectonics -The theory that the lithosphere is divided into plates that are always moving, breaking apart, and colliding! 2. Most plates are made up of both oceanic and continental crust.

3. Look at the maps on pages 308-309 3. Look at the maps on pages 308-309. Compare the North American plate with the Pacific Plate? North American plate is smaller and has more continental crust than the Pacific plate.

Plate Boundaries The three main types of plate boundaries are: Divergent boundary -a place where 2 or more plate are moving AWAY from each other. Mid-Ocean Ridge - a chain of mountains beneath the ocean. Rift - highest part of the mid-ocean ridge where plates move apart. Sea-floor spreading - new lithosphere formed along the mid-ocean ridge from the ocean bottom cooling and becoming rigid.

Plate Boundaries Convergent boundaries - Where 2 plates move TOWARD each other. Transform Fault Boundary - 2 plates moving PAST each other. a. San Andreas fault in California is a famous transform fault boundary where Earthquakes occur from the plates grinding past each other.

Plate Movements change Earth’s Surface Pangea - a supercontinent where all of the continents were connected about 220 Million years ago. Why do scientists believe there was a super continent that existed about 220 million years ago?

Pangea

6-3 What Causes Earthquakes and Volcanoes? Fault - a break in Earth’s crust where rock on one side can move in relation to rock on the other side.                           

Earthquake - A vibration in Earth's crust, caused by the release of energy at a fault. Focus - The point inside Earth where an earthquake begins. Epicenter - The point on Earth’s surface directly above the focus of an earthquake.

P waves - Fastest waved caused by earthquakes, they compress and expand the ground as they travel. S waves - Second-fastest waves caused by earthquakes that move across the direction the p waves are traveling. They can move up and down or side to side.

7. What causes an earthquake? Pressure along faults that is released in the form of waves of energy cause an earthquake.

Measuring Earthquake Strength and Damage Seismograph readings can be used to calculate an earthquake’s strength. Richter scale - estimates the amount of energy released by an earthquake. Moment Magnitude scale - uses the amplitude of earthquake waves to estimate and earthquake’s energy and fault rupture area. Mercalli intensity scales - measure an earthquakes damage.

Tsunami - A powerful earthquake that occurs beneath the ocean that causes the ocean floor to rise and fall and produces a large destructive wave that can travel great distances. What are the effects of a tsunami? Tsunamis flood costal regions and cause major damage and erosion.

Volcanoes Volcanoes - A mountain formed when molten rock is pushed to Earth’s surface and builds up. What causes a volcano to form? Magma that rises to Earth’s surface and erupts from a vent causes a volcano.

3. Types of volcanoes: Shield -broad, dome shaped that may erupt many times in a period of more than a million years. Composite - may erupt on and off for as long as a million years. Cinder - have steep sides and erupt for a short period of time. Most are less than 300m tall.

What caused the Hawaiian Islands to form? As the Pacific plate moved over a hot spot, magma erupted and formed a chain of volcanoes.