View
218
Download
0
Category
Tags:
Preview:
Citation preview
Chapter 7Chapter 7
Plate Tectonics
Chap 7, Sec 3 (The Theory of Plate Tectonics)
What we will learn:
1. Describe the 3 types of plate boundaries.
2. Explain the difference between the 3 types of faults.
3. Describe the 3 types of stress that deform rock.
Vocab:1. plates – separate sections of the
lithosphere.
2. plate tectonics –theory that states that pieces of lithosphere are in constant motion, driven by convection currents in the mantle.
3. faults – breaks in Earth’s crust where plate boundaries form.
4. transform boundary – a place where two plates slide past each other in opposite directions (earthquakes are frequent).
5. divergent boundary – the place where two plates move apart, or dive away (most occur at the mid-ocean ridge).
6. rift valley – develops on land, where two plates diverge.
Mid Ocean RidgeMid Ocean Ridge
7. convergent boundary – the place where two plates come together, or collide. (the density of the plates dictates which one comes out on top).
Ex: at the deep ocean trench where the oceanic crust (basalt) is more dense than the continental crust (granite)
which is less dense
SubductionSubduction
Types of StressTypes of Stress
• Deformation: Process that changes the shape of rock because of stress.
• Tension: stress that forms when forces act to stretch an object (rubber band)
• Compression: stress that forms when forces squeeze an the rock.
• Shearing: pushes mass of rock in 2 opposite direction.
FaultsFaults
• Surface where rocks break or slide past each other.
• Hanging wall: the wall you would han g from.
• Footwall: the wall you put your foot on.
FaultsFaults
• Normal Fault: Rocks are pulled apart; hanging wall moves down relative to the footwall.
• Reverse Fault: rocks are pushed together by compression, hanging wall moves up relative to footwall
FaultsFaults
• Strike-slip Fault: rocks are moved horizontally by opposite directions.
Mountain BuildingMountain Building
• Folded Mountains: form where continents have collided.
• Applachians: formed when North America and Africa collided.
Hint: push on the edges of a piece of paper towards the center.
Mountain BuildingMountain Building
• Fault-block mountains: form when tension from normal faults forces blocks of rock to move upward
Recommended