Unit 1: Earth as a System. Section 1: Plate Tectonics and the Rock Cycle

Transcription

1 Unit 1: Earth as a System Section 1: Plate Tectonics and the Rock Cycle

2 Earth s Realms Earth is divided into 4 major realms: Atmosphere gases surrounding earth Hydrosphere - earth s supply of water Lithosphere - soil and rock of the earth s crust Biosphere contains earth s communities, ecosystems, and landscapes; relies on the other three realms for survival.

3 Internal Planetary Processes The earth s consists of: Core: innermost zone with solid inner core and molten outer core that is extremely hot; made primarily of Iron and Nickel Mantle: solid rock with a less-rigid outer part (asthenosphere) that is melted, pliable rock. Crust: Outermost zone which underlies the continents; the most abundant element in Earth s crust is Oxygen.

4 Internal Planetary Processes Layers of the earth that directly affect us Lithosphere Outermost rigid rock layer made up of tectonic plates Asthenosphere Upper mantle comprised of hot, soft rock

5 Internal Planetary Processes Plate Tectonics- study of the processes by which the lithospheric plates move over the asthenosphere Plate Boundary - where 2 plates meet Divergent Convergent Transform

6 Volcanoes Abyssal floor Trench Abyssal plain Craton lp lai n Abyssal hills Abyssal Oceanic floor ridge Folded mountain belt Continental shelf Ab ys sa Oceanic crust (lithosphere) Mantle (li thospher Continental slope Continental rise e) Continental crust (lithosphere) Mantle (lithosphere) Mantle (asthen osphere) Fig. 15-2, p. 336

7 Te ct pl oni at c e Collision between two continents tonic c e t nic Ocea plate Spreading Oceanic tectonic center plate nt eme v o m Plate Subduction zone Continental crust Oceanic crust Ocean trench Plate mov ement Oceanic crust Continental crust Material cools Cold dense as it reaches material falls the outer back through mantle mantle Hot Mantle material convection rising cell through the mantle Two plates move towards each other. One is subducted back into the mantle on a falling convection current. Mantle Hot outer core Inner core

8 Divergent boundary plates move apart in opposite directions. Example: Mid-Atlantic Ridge

9 Convergent boundary the plates push together. At most convergent plate boundaries, the oceanic lithosphere is carried downward under an island or continent, creating a subduction zone. Earthquakes are common here. Can also lead to formation of a volcanic mountain range. Example: Japan, Himalayas

10 GEOLOGIC PROCESSES Transform boundary plates move horizontally in opposite but parallel directions. Plates snag on one another and build pressure, then release dramatically! The San Andreas (CA) Fault is an example of a transform fault.

11 Trench Volcanic island arc Craton Transform fault Su bd Lithosphere Asthenosphere Divergent plate boundaries Lithosphere Rising io n magma zo n Asthenosphere e uc t Convergent plate boundaries Lithosphere Asthenosphere Transform faults Fig. 15-4b, p.

12 JUAN DE FUCA PLATE EURASIAN PLATE NORTH AMERICAN PLATE ANATOLIAN PLATE CARIBBEAN PLATE ARABIAN AFRICAN PLATE PLATE PACIFIC PLATE SOUTH AMERICAN NAZCA PLATE PLATE SOMALIAN SUBPLATE CHINA SUBPLATE PHILIPPINE PLATE INDIAAUSTRALIAN PLATE ANTARCTIC PLATE Divergent plate boundaries Convergent plate boundaries Transform faults Fig. 15-4a, p.

13 Pacific Ring of Fire

14 Earthquakes Caused by the release of accumulated energy as rocks in the lithosphere suddenly shift or break Occur along faults (often at plate boundaries) Energy released as seismic waves

15 Tsunami Giant undersea wave caused by an earthquake, volcanic eruption or landslide Travel > 450 mph Tsunami wave may be 1m deep in ocean Becomes 30+m high on shore Magnitude 9.3 earthquake in Indian Ocean (2004) Triggered tsunami that killed over 230,000 people in South Asia and Africa

16 Volcano Volcanoes occur in three locations: Subduction zones (convergent plate boundaries) Divergent plate boundaries Hot spots (Hawai i) Location on crust where magma reaches surface as lava.

17 The Rock Cycle

18 The Rock Cycle The interaction of processes that change rocks from one type to another Three types of rocks: Igneous Sedimentary Metamorphic All three types of rocks are being recycled and converted to the others

19 Erosion Transportation Weathering Deposition Igneous rock Granite, pumice, basalt Sedimentary rock Sandstone, limestone Heat, pressure Cooling Heat, pressure, stress Magma (molten rock) Melting Metamorphic rock Slate, marble, gneiss, quartzite Fig. 15-8, p. 343

20 Igneous Rock Description forms the bulk of the earth s crust. It is the main source of many non-fuel mineral resources; Formed by the cooling of magma/lava. Classification Intrusive Igneous Rocks formed from the crystalization of magma below ground (Granite, Gemstones, etc.) Extrusive Igneous Rocks formed from the solidification of lava above ground (Pumice, Obsidian, etc.)

21 Sedimentary Rock Description rock formed from the deposition of sediments. Most form when rocks are weathered and eroded into small pieces, transported, and deposited.

22 Metamorphic Rock Description when preexisting rock is subjected to high temperatures (which may cause it to partially melt) and/or high pressures, it forms metamorphic rock Location deep within the earth

23 Progressive Metamorphism One form of rock changing into another. Examples: shale->slate->schist->gneiss coal->graphite->diamond granite->gneiss

24 Primary vs. Secondary Succession During succession organisms modify their surroundings which in turn creates suitable conditions for succeeding organisms Following major changes in the surface of the planet, primary succession begins

25 Primary vs. Secondary Succession (cont.) Secondary succession begins on the soil where there was living organisms previously, but have vanished due to natural or anthropogenic (human-made) causes