I. Primary Landforms a. Created by plate tectonics: a theory that says that Earth’s surface is broken up into plates that are constantly moving

i. When plates pull apart 1. Rifts can form (gaps in Earth’s surface) a. Example: Great Rift Valley in East Africa 2. Mid-ocean ridges can form a. Example: Mid-Atlantic ridge

ii. When plates collide 1. when an ocean plate and a continental plate collide, the ocean plate slides under the continental plate (called subduction) a. volcanic mountains can form i. Example: Andes Mountains/Ring of Fire b. trenches can form (deep cuts in the ocean floor) i. Example: Mariana Trench c. earthquakes can happen i. Example: Ring of Fire

2. when two continental plates collide, the Earth’s crust crumples up a. mountains form i. Example: Himalaya Mountains b. plateaus can form i. Example: Plateau of Tibet

iii. When plates slide past each other 1. faults can form (crack in Earth’s surface) and earthquakes can happen i. Example: San Andreas Fault in California

II. Secondary Landforms: Occur when primary landforms are broke down a. created by weathering: a process in which rock is broken apart into smaller pieces i. can be done by water ii. ice (water can seep into cracks, freeze, and then break the rock) iii. heat iv. chemicals (acid rain) v. plants (lichens)

b. also created by erosion: a process by which weathered bits of rock are moved elsewhere i. can be done by moving water 1. canyon (deep valley with steep sides) 2. cliff (a steep face of rock can be caused from crashing waves) 3. alluvial fan (landform created by the deposit of sediment at the base of a mountain) 4. flood plain (landform created when rivers flood their banks and deposit sediment) 5. delta (landform created by the deposit of sediment at the mouth or end of a river)

ii. wind 1. plateau (an area of flat land at a high elevation) 2. sand dunes

iii. ice 1. valleys (area of low land between hills or mountains) can form when glaciers move