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
Lithospheric Plates
Portions of the lithosphere that move independently of one another movement causes earthquakes
Boundaries Affecting California
North American Plate
Pacific Plate
Form the “ring of fire”
