Download - Topic 12
TOPIC 12 Earths Dynamic Crust and Interior
Lithosphere:Layer of rock that forms the outer shell of the earth
Crust:The upper part of the lithosphere
Small Scale Crustal ChangesLaw of original
Horizontality:Sedimentary rocks form flat horizontal layers
The Four ways that Rock Layers are Changed
1) Folding:
Compression causes layers to bend
2) Tilting:
Layer of strata get tipped
The Four ways that Rock Layers are Changed3)
Faulting:Rocks are displaced along a crack called a fault
4) Uplift:
Rock layers get pushed up many meters
Earthquakes and Igneous Activity Including Volcanoes
Earthquake:
Natural rapid shaking of the earthquake
The stored energy in the ground is released as seismic waves
Focus:
Place where the earthquake originatesEpicenter:
Place on earth’s surface directly above focus
Fault:
Plane where the rock breaks
Example
Earthquakes and Igneous Activity Including Volcanoes
Seismograph:
Instrument used to detect and measure quakes
Seismogram:
Actual recording of the quake
How it WorksAgain
3 Types of Earthquake Waves
1) P-waves (primary): Compression wave that vibrates in the same direction as particles
2) S-waves (secondary): Shear wave that moves perpendicular to the particles
3) L-waves (surface): Travel on surface and cause the damage
Properties of Seismic Waves
-P-waves are fastest and arrive at the seismograph 1st-Waves travel faster in more dense material-Waves travel faster as pressure is increased-P-waves travel through solids, liquids and gasses-S-waves only travel through solids
Location of an Epicenter
The location of any earthquake can be found by knowing the distance from the epicenter to three seismic stations.Process1) Find the time difference between P and S waves 2) Mark the time difference on scrap paper3) Use ESRT to find distance4) Repeat for 2 more seismograms
Location of an EpicenterWhat does the distance from one
seismograph tell us?The quake was somewhere on the circle
What does the distance from one seismograph tell us?
What does the distance from two seismographs tell us?Narrows it down to 2 possibilities
Exact location
Finding the Origin Time of Earthquakes
1) Use the distance to determine travel time2) Subtract travel time from arrival time
AT 10:27:35TT - 7:42
10:19:53
AT 15:26:12TT - 3:20 15:22:52
Magnitude of Earthquakes
Measure of the intensity of an earthquakeMercalli Scale:
Rates the effects of the earthquake
Richter Scale:
Measures magnitude of actual energy released
Tsunami:
Seismic sea wave triggered by a quakeHow they work
Igneous Activity and Volcanoes Volcano:
Mountain made of extrusive igneous rocksVolcanic
Eruption:Giving off of gasses lava and rock
Mount Saint HelensPyroclastic Fl
ow
Zones of Crustal ActivityRing of Fire:Area of volcanic activity surrounding the
PacificWhere are other areas of activity located?
Plate Boundaries
A Model of Earth’s Interior
Scientists use seismic waves to create a modelWhat happens to pressure as you go from crust to core?What happens to temperature as you go from crust to core?
Zones of the Earth LithosphereThinnest layer (shell on a hard boiled egg)2 Types of Crust1) Continental Crust:
Rock that makes up the continentsCompositio
n:Granite
Density:
2.7 g/cm3
2) Oceanic Crust:
Rock that makes up the ocean floorCompositio
n:Basalt
Density:
3.0 g/cm3
Zones of the Earth Moho:
The interface between lithosphere and the mantleAsthenospher
e:Upper mantle (like silly putty) able to flowMantl
e:Layer of rock between the Asthenosphere and outer core
Core:
Central part of the earth
Makes Up 80% of Earth’s Volume
2 Cores1) Outer CoreComposition
: Iron and NickelState of Matter:Liquid
2) Inner Core Composition: Iron and NickelState of Matter:Solid
NO WE ARE NOT GOING TO WATCH THE MOVIE THE CORE BECAUSE IT IS DUMB
Also Dumb!!
Plate Tectonic Theory
What is a plate?
Large section of the lithosphereThe lithosphere of the earth is made up of 12 major PlatesHow fast do these plates move? 3 to 10 cm/yr.
Evidence of Plate Tectonics
Fossils:
Land fossils match on different continentsGeolog
y:Rock types and ages match on different continentsPuzzle
:Continents fit together like a puzzle
The Driving Force Behind Plate Movements
The Three Types of Plate Boundaries1)
Divergent:Plates move away from each other
a.) Midocean ridges:
Mountain ranges in the middle of oceans
b.) Rift valleys:
Deep valleys formed from separating plates
How it happens
The Three Types of Plate Boundaries
2) Convergent:
Plates are coming together3 Varieties of ConvergenceOceanic-Oceanic:
2 oceanic plates collide-Volcanic island arcs-Destruction due to subduction
The Three Types of Plate Boundariesb) Oceanic-
Continental:Collision of oceanic and continental plates
-Mountain ranges and volcanoes-Deep sea trenches
The Three Types of Plate Boundariesc.) Continent-
Continent:2 continental plates collide
-Mountain ranges -Earthquakes
Creation and Destruction
The Three Types of Plate Boundaries3.) Transform Plate
Boundaries:Plates grind horizontally
-Deformation of rock and many quakes
San Andreas Fault
Hot Spots
Hot Spots:
Major volcanic activity in the middle of plate-Caused by concentrations of radioactive
elements-Ex: Hawaii and the GalapagosHow do they form
Effects of Plate Tectonics
Appearance of Continents:
Fit togetherFeatures of Landmasses:
Fossils on different continents, coal bed correlation, tropical fossils in NYS, marine fossils on mountainsHeat and Age
PatternsAge:
Edges of the ocean is the oldest, new material at MOR
Heat Patterns:
Rock gets cooler and denser towards the continents
Magnetic Patterns-Poles have reversed throughout
history
Sea Floor Spreading
Polarity