1. EARTH DYNAMICS

2. Plate Motion

3. Plate Motion – Vertical  Thicker parts of the crust rise until they equal the thickness of mantle below, this is called isostasy.  Subsidence – downward vertical motion of Earth’s surface  ex. heavy glaciers dent Earth’s crust (a)  Uplift – upward vertical motion of Earth’s surface  ex. crust rises once glaciers melt away (b)

4. Plate Motion - Horizontal  Stress – force acting on a surface  Compression – squeezing (convergent boundary)  Tension – pulls apart (divergent boundary)  Shear – parallel force in opposite directions (transform boundary)  Strain – change in shape of rock due to stress  Elastic – rocks go back to their normal shape  Plastic – rocks are permanently changed

5. Land Formations

6. Land Formations - Compression  Mountains  occur when two continental plates converge  Ocean Trenches  occur during subduction, when one plate sinks below another  Volcanic Island Arc  curved line of volcanoes that form parallel to a subduction plate boundary

7.  Mid-Ocean Ridges  occur where two oceanic plates separate  Rift Valleys  occur where two continental plates separate Land Formations - Tension

8. Land Formations – Shearing  Transform Faults  occur where plates slide horizontally past each other  Fault Zone – an area of many fractured pieces of crust along a fault

9. Mountain Building

10. Mountain Formation  Convergent Plate Boundary  When two continental plates collide rocks are pushed upward  Mountains can become smaller through erosion and weathering

11. Types of Mountains  Folded Mountains  made of layers of rocks that are folded upward when continental plates collide  always fold perpendicular to the direction of compression  Fault-Block Mountains  parallel ridges that form where blocks of crust move up or down along faults  formed through tension

12. Types of Mountains  Uplifted Mountains  when large regions rise vertically with little deformation  Volcanic Mountains  molten rock and ash from erupting volcanoes hardens and forms a mountain

13. Continent Building

14. Continental Growth  Continents can grow in two ways:  volcanic eruptions add igneous rocks  tectonic plates carry island arcs, whole continents, or pieces of continents with them

15. Continental Interiors  Plains  large area of level or rolling land  flattened by millions of years of erosion and weathering  Basins  regions of low elevation  rich in fossil fuels

16. Continental Interiors  Plateau  flat regions of high elevation  form through uplift, or from large lava flows