The Rock Cycle
• Interaction of Earth Processes (internal and surface)
• Rocks continually
– Created and destroyed
– Transformed
– Recycled
• Igneous Rocks
– Newly formed rocks
– Crystallized from liquid rock
• Sedimentary Rocks
– Recycled earth materials
– Particles and solutions -weathering
• Metamorphic Rocks
– Heat and pressure change rocks
Rocks
• Composed of minerals (quartz, feldspar, mica, etc.)
• Rock texture - reflects forming process
• Used to determine processes and earth history
• Scientific and economic importance
Igneous Rocks
• Crystallize from liquid rock (Magma)
• Crystalline texture
• Melting occurs at convergent and divergent boundaries
– Top of the mantle, or base of the crust
– Bringing heat up or taking rocks down
Igneous Rock Texture
• Crystal Size = rate and depth of cooling
• Cools fast at surface - small crystals - volcanic
• Cools slowly deep w/i crust - large crystals - plutonic
Igneous Rock Composition
• Composition tells us - location, location, location…
• Lighter colors = continents
– Granite, rhyolite, andesite
• Darker colors = oceans
– Basalt & gabbro
Discuss & answer the following with the person next to you……
• Examine the photo’s of the “heads”
• Does the rock appear to be plutonic or volcanic?
• Where did it form, and how did it get exposed at the surface?