Chapter 9 The Dynamic Planet Flashcards
Igneous
Formed from molten material; cooling
Sedimentary
Formed from compaction or chemical processes
Examples: Classic: Sandstone
Chemical: Limestone
Organic: Coal
Metamorphic
Formed from pre-existing rock under heat and pressure
Examples: Sandstone to Quartzite
Three Rock Types
Igneous-molten
Sedimentary-compaction
Metamorphic- pre-existing rock
Sedimentary Rocks Divided into 3 categories
Clastic - Formed from broken rock material
Chemical - Formed primarily from chemical reactions
Organic-Formed from fossils
Earth’s Structure
Lithosphere – Rigid Layer - Combo of crust and solid part of uppermost mantle
Athenosphere – Plastic Layer - “weak”, partly motlen, portion of upper mantle
Plate Tectonics:
Convergent Boundaries
- When plates move toward each other “push”
- Subduction
- Occur in areas of crustal collision and subduction zones
- Creates earthquakes, mountains, volcanoes in coastal areas
Plate Tectonics:
Divergent Boundaries
• Plates spread apart; pull
• Magma rises and lava flows to fill gap
• Seafloor spreading; forms mid-oceanic ridges
- Example: East African Rift System
Plate Tectonics:
Transform Boundaries
• Move (slide)past one another;scraping each other
• No subduction or volcanic activity
• Form a fault or fracture in Earth’s crust
• Creates shallow earthquakes
• Example: San Andreas Fault System
- Pacific and North American plates
- Moves ≈3 inches per a year
Plate Tectonics:
Hot Spots
• Plumes of magma that rise from mantle • Creates volcanoes and thermal effects in groundwater and crust • Occurs beneath oceanic and continental crust Example: Hawaiian Islands
Subduction
One plate goes under another plate
Endogenic System
- Processes operating at Earth’s interior
- Driven by heat and decay
Exogenic System
Processes operating at Earth’s surface
- Driven by solar energy; movement of water
Geologic Time Scale
Current Era and Period
Earth’s History
Era: Cenozoic Period:Holocene
≈10,000 years ago to now
Earth’s Structure:
Inner Core
Solid
Earth’s Structure:
Outer Core
Molten; Liquid
Earth’s Structure:
Lower Mantel
Solid
- Silicon, Iron, and Magnesium
Earth’s Structure:
Upper Mantle
Partly molten, partly solid
Silicon and Oxygen
Earth’s Structure:
Crust
Top Layer
5-25 miles thick
Oceanic Crust
New
Higher density
Composed basalt; granular composition
Continental Crust
Old
Lower density
Composed mainly of granite
Intrusive Igneous Rocks
Formed from magma that cools slowly. Granite rocks
Example: Batholith:Sierra Nevada
Volcanic Necks: WY and NM
Extrusive Igneous Rocks
Magma forced to the surface
Example: Basalt Lava Flow Obsidian
Pangaea Theory
Supercontinent that included all current land masses
