Geology 12. Presents. UNIT 3. Chp 10 Earth’s Interior and Isostacy Chp 11 Ocean Basin Chp 12 Plate Tectonics Chp 9 Seismology Chp 13 Structure. Handout WS 10.1 Note Helper. Chapter 10 Earth’s Interior and Isostacy. atmosphere. hydrosphere. continental crust.
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Handout WS 10.1 Note Helper
Oceanic Crust 0.16 3.0 upper: basalt
Continental Crust 0.44 2.7 granodiorite
Mantle 83 3.3 – 5.7 peridotite
Outer Core 15.7 9.9 – 12.2 88%Fe, +S,O2,Ni, K
Inner Core 0.7 12.6 – 13.0 80 - 90% Fe, +Ni
i) rock density: higher density speeds waves
(ex: Earth’s density increase towards the core: S-waves travel faster at the bottom of the mantle)
ii) Rock elasticity = tendency to return to original shape
higher elasticity increases wave speed
(ex: P-waves travel slow through liquid outer core than through solid inner core)
Low velocity zone = asthenophere
EQ in every direction (like ripples on a pond)
Please refer to WS 10.1, p.2 of notehelper, bottom diagram.
Upper mantle (6.75 km.sec)
Low velocity zone = Asthenosphere
Upper Mantle (6.75 km.sec)
How Layers of Earth was Determined (6.75 km.sec)
Hand out WS 10.2 Note Helper
Island arc (volcanoes)
Heat flow Cal/cm2/sec
Remember Chp 7! lowest at trenches
Region Temperature Geothermal Gradient
Crust base: 800- 1200 25
Mantle base: 3500-5000 1
Core base: 6500 <1
m1 x m2
Double the distance = ¼ the gravity
a) Earth is not round: less gravity at equator
b) less gravity at high altitudes lowest at trenches
2. Centrifugal force at equator “throws” you away from Earth = less gravity
3. Density of rock below Earth = less gravity
(Positive gravity anomaly = more gravity)
Centrifugal Force is seen here with indirect high tides Earth = less gravity
Positive gravity anomaly Earth = less gravity
Negative gravity anomaly
Low density sedments
Salt dome (low density
a) glaciers/ice age
b) sediments accumulates in a delta or basin
(Evidence: sunken cities, docks, forests, beaches)
a) glaciers melt/recede
b) erosion of a mountain
(Evidence: above sea-level: docks, beaches, marine fossils)
1. on denser mantle.
Ice melts (i.e. Hudson’s Bay
Mtn’ on denser mantle.
Low density root
See question 11, WS 12.2 on denser mantle.
See question 16, UNIT 3 Review WS on denser mantle.
True north pole
Inclination/tilt of compass needle
Lines of magnetic force
True north pole (Santa’s home)
magnetic north pole
Important for surveying…more on this in Chp 13
The Magnetic Pole moves clockwise (precesses) CW around and generally near the True Pole. The large scale movement of the magnetic pole/magnetic field indicates plate movement
See WS 10.2 Note helper, top of page 2.
+ mag’ anom’ generally near the True Pole. The large scale movement of the magnetic pole/magnetic field indicates plate movement
- mag’ anom’
Lava flow/ diamond pipe
Salt dome/ reef