Essc Exam 2
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- Parts of a volcano
- crater- bowl shaped area around central opening, lava-molten rock that flows from the vent above earth's surface,magma- molten rock below the earths surface, pipe-long tube through which magma moves, vent-the opening which molten rock and gas leave the volcano
- Why does magma rise
- b/c liquid magma is less dense than the surronding solid material
- What factors determine if a volcano will erupt?
- amount of gas dissolved in the magma, viscosity (resistance of magma), Magma temp (hotter it is the more fluid it is), silica content (the more the thicker it is)
- 3 Stages of a volcano
-
active-live
dormant- sleeping expected to become active in the future
Extinct- dead, not erupted for thousands of years - 3 types of volcano
- sheild, cinder cone, and composite
- Sheild Volcano
- thin layers of lava pour out gradually and build up a wide, gently sloping mt Ex:Mauna Loa
- Cinder Cone
- produce ash, cinders, and bombs, steep cone shpaed hill Ex:Paricutin
- Composite Volcano
- tall mountains, alternating ash and cinder and bombs
- What is an earthquake?
- the vibration of Earth produced by the rapid release of energy.
- Focus
- the source where enery radiates in all directions
- What are Earthquakes associated with?
- faults, explained by plate tectonics
- Body waves
- primary waves, secondary waves
- p-waves
- push-pull waves they can travel through all mediums, they arrive first
- s-waves
- right angle waves, they can travel through solids, they arrive second
- Surface Wave
- like ocean swells, they have an up and down motion and a side-to-side motion, produce the most damage, they arrive last
- epicenter
- the location on the surface directly above the focus
- 2 ways to measure a earthquake
- Mercalli Intensity Scale, Richter Scale
- Tsunami
- seismic sea waves, produced by an earthquake
- law of superposition
- in a undeformed sequence of sedimentary rocks the oldest rock is on the bottom, and the youngest rock is on top
- Principle of Original Horizontality
- the layers of sediment are generally deposited in a horizontal position. if the layers are flat they have not been disturbed, and have their original horizontality
- Prinicple of Cross-Cutting relationships
- when a fault cuts through or a magma intrudes and crystallizes we can assume that the fault or the intrusion is younger than the rocks it intruded into
- unconformities
- gap in the geogical record, disconformity-erosional
- What are fossils?
- the remains or traces of prehistoric life, important time indicators
- Principle of Fossil Succession
- fossil organisms suceed one another in a definite and determinable order, and therefore any time period can be recognized by its fossil content
- What is a fossil index
- widespread geographically and are limited to a short span of geologic time
- radiometric dating
- absolute dating
- Precambrian
- mostly algee and microfossils
- 3 Eras
- paleozoic-mostly invertebrates, mesozoic- mostly dinosaurs, cenozoic- mostly mammals