1 / 34

Geology Unit beginning 2-18-14

Geology Unit beginning 2-18-14. Rock cycle, Plate Tectonics, Volcanoes, Earthquakes. The Rock Cycle. The rocks of the Earth are always positioned somewhere on the rock cycle. Three types of rocks: Igneous Sedimentary Metamorphic. Igneous rocks.

darius-padilla
Download Presentation

Geology Unit beginning 2-18-14

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Geology Unitbeginning 2-18-14 Rock cycle, Plate Tectonics, Volcanoes, Earthquakes

  2. The Rock Cycle • The rocks of the Earth are always positioned somewhere on the rock cycle. • Three types of rocks: • Igneous • Sedimentary • Metamorphic

  3. Igneous rocks • Formed from the crystallization of magma or lava • Magma below Earth’s surface & lava is magma that flows out onto Earth’s surface • Can form on Earth’s surface (extrusive) or below Earth’s surface (intrusive) • Cools quickly on Earth’s surface • Cools slowly below Earth’s surface

  4. Sedimentary Rocks • Sediments – pieces of solid material that have been deposited on Earth’s surface by wind, water, ice, gravity, or chemical precipitation • When these sediments are cemented together = sedimentary rock

  5. Sedimentary Rocks • Sediments created by weathering • Erosion & Transport – sediments move from one location to another via wind, water, gravity, & glaciers • Deposition – sediments are laid down on the ground or at the bottom of a body of water • Lithification – physical & chemical processes that transform sediments into sedimentary rocks (burial, compaction, & cementation: mineral growth cements the rocks together)

  6. Metamorphic rocks • Rocks change form while remaining solid • Pressure & temperature under Earth’s surface are high but not high enough to melt minerals and form magma • So… • Metamorphic rocks • are formed!

  7. The Rock cycle • Sequence by which rocks are formed, altered, destroyed, and reformed as a result of external and internal processes of the Earth. • (forces: physical & chemical weathering, heat & pressure, deposition, foliation & bedding) • (energy: heat & mechanical (gravitational potential)) • Metamorphic → igneous or sedimentary. • Igneous → metamorphic or sedimentary. • Sedimentary →igneous or metamorphic.

  8. Continental Drift • Alfred Wegener- 1912 • Supercontinent Pangaea • Evidence- similarities in: • types of fossils (Mesosaurus) • shape and fit of continents • rock formations; age and structure

  9. Evidence of continentaldrift

  10. Wegener’s proposed ‘Pangaea Puzzle’

  11. Figure 2.14b

  12. Figure 2.14c

  13. Figure 2.14d

  14. Plate Tectonics • Entire surface of the earth moves, not just the continents • Lithosphere- crust and uppermost mantle • Plates- lithosphere is broken into plates that move over the more ‘fluid’ or ‘plastic’ asthenosphere

  15. Earth’s major lithospheric plates

  16. Evidence for plate tectonics – sea floor spreading • Mid-ocean ridge discovered by sonar after WWII • A mid-ocean ridge is a continuous chain of submarine volcanic mountains • Sea floor spreads at ridges and is destroyed at trenches.

  17. Plate Tectonics • Mechanisms of the lithosphere: • Mantle Convection • Ridge Push • Gravity Pull

  18. Mantle convection Currents formed in the mantle by the transfer of energy between Earth’s hot interior and its cooler exterior. Hot mantle material is less dense and so is forced upwards while cooler parts sink towards the core.

  19. MANTLE CONVECTION

  20. Ridge push • A force applied to spreading centers. • New hotter material is brought up and floats higher than the mantle to form ridges. • Gravity moves the ridge down & away from the center so more mantle material can come up. • It makes plates move away from each other.

  21. Gravity pull • Cold, dense oceanic crust sinks into the subduction zone and pulls the whole crust with it. • The force of the sinking plates causes the plates to pull away from each other & ride atop the convection currents from the mantle.

  22. Plate Boundaries • Convergent boundaries-plates collide- form island arcs or volcanic mountain chains • Divergent boundaries- plates move apart • Shear or Transform boundaries- plates slide past one another- like the San Andreas Fault

  23. Plate boundaries • Convergent Boundary • depending on the crust forms mountains (c-c), volcanic arcs (o-c), and island arcs (o-o). • Divergent Boundary • oceanic- oceanic: ocean ridges form. continental- continental: rift valleys form. • Transform Boundary • forms different faults: normal, reverse, strike slip.

  24. Divergent Boundaries and Ocean Ridges Ocean Ridges - produced along divergent boundaries. Plates diverge because of the mantle convection currents. They push the plates up & this causes the ridge.

  25. Convergent Boundaries and Ocean Trenches When a continental and an oceanic plate converge and descend to the subduction zone. Ocean trenches are normally parallel to a volcanic island arc, also formed by convergent boundaries.

  26. Convergent Boundaries and Mountain Ranges Mountain ranges form when two continental boundaries converge. Since neither is dense enough to go into the subduction zone, they rise up and form large mountain ranges.

More Related