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Announcements I will be writing PS #1 over the weekend, and posting it by Monday… It will be due Feb 9 th .
Clarification: The angle of Earth’s tilt does not change during the year! Views of the Earth from the Sun’s perspective It...
The axis is always parallel to itself.
Quiz 2!
2. Sun Angle: insolation curves
2. Sun Angle: insolation curves Winter Summer Autumn Spring Winter
Insolation 23.5 o  axis tilt 0 o  axis tilt
An Equation for the Sun Angle On an equinox Declination = 0 °
An Equation for the Sun Angle On an equinox Declination = 0 ° At the equator Lat = Sun angle = 0 ° 90 °
An Equation for the Sun Angle On an equinox Declination = 0 ° At the north pole Lat = Sun angle = 90 °N 0 °
An Equation for the Sun Angle On an equinox Declination = 0 ° At some latitude x Lat = Sun angle = x °N 90 °- x° x ° 90 °-...
But then we have to adjust for declination! Equator is sub-solar point North pole tilted toward the sun North pole tilted ...
But then we have to adjust for declination! Sun Angle = 90 °-x° Sun Angle = 90 °-x° Sun Angle = 90 °-x°-23.5° Sun Angle = ...
Final Formula Sun Angle at Noon = 90 ° - Latitude° + declination° Summer Note: this formula is for the angle with the sout...
Lithosphere:  solid Earth
Geologic time: dating <ul><li>2 types </li></ul><ul><li>Relative Dating = sequential age </li></ul><ul><ul><li>based on po...
Dating using Geological Laws <ul><li>Law of superposition </li></ul><ul><ul><li>- younger rocks are deposited on top of ol...
Grand Canyon Layers
<ul><li>Law of original horizontality </li></ul><ul><ul><li>- sedimentary rocks & lava are originally laid down horizontal...
A roadcut photo that I stole… WV maybe?
<ul><li>Law of cross-cutting relations </li></ul><ul><ul><li>rocks that intrude into other rocks are younger than their ho...
Roadcut near Moab, UT
A B C D Events: A deposited B deposited C deposited D deposited Faulting Erosion of Surface X Erosion of Canyon But in wha...
Events: A deposited B deposited C deposited D deposited E deposited F deposited G deposited Folding Erosion of Surface X O...
Events: A deposited B deposited C deposited D deposited E deposited F deposited Folding Faulting Erosion of Surface X Eros...
Events: Cooling of Granite A Deposition of Sandstones B, E, & I Deposition of Shales C & H Deposition of Limestone D & F C...
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Lecture5 lawsofgeology

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Transcript of "Lecture5 lawsofgeology"

  1. 1. Announcements I will be writing PS #1 over the weekend, and posting it by Monday… It will be due Feb 9 th .
  2. 2. Clarification: The angle of Earth’s tilt does not change during the year! Views of the Earth from the Sun’s perspective It only looks that way from the sun’s frame of reference .
  3. 3. The axis is always parallel to itself.
  4. 4. Quiz 2!
  5. 5. 2. Sun Angle: insolation curves
  6. 6. 2. Sun Angle: insolation curves Winter Summer Autumn Spring Winter
  7. 7. Insolation 23.5 o axis tilt 0 o axis tilt
  8. 8. An Equation for the Sun Angle On an equinox Declination = 0 °
  9. 9. An Equation for the Sun Angle On an equinox Declination = 0 ° At the equator Lat = Sun angle = 0 ° 90 °
  10. 10. An Equation for the Sun Angle On an equinox Declination = 0 ° At the north pole Lat = Sun angle = 90 °N 0 °
  11. 11. An Equation for the Sun Angle On an equinox Declination = 0 ° At some latitude x Lat = Sun angle = x °N 90 °- x° x ° 90 °- x°
  12. 12. But then we have to adjust for declination! Equator is sub-solar point North pole tilted toward the sun North pole tilted away from the sun Equator is sub-solar point Summer Winter Fall Spring
  13. 13. But then we have to adjust for declination! Sun Angle = 90 °-x° Sun Angle = 90 °-x° Sun Angle = 90 °-x°-23.5° Sun Angle = 90 °-x°+23.5° Summer Winter Fall Spring
  14. 14. Final Formula Sun Angle at Noon = 90 ° - Latitude° + declination° Summer Note: this formula is for the angle with the southern horizon, so it makes the most sense to only use it in the Northern Hemisphere
  15. 15. Lithosphere: solid Earth
  16. 16. Geologic time: dating <ul><li>2 types </li></ul><ul><li>Relative Dating = sequential age </li></ul><ul><ul><li>based on positions of rocks relative to each other </li></ul></ul><ul><ul><li>e.g., rock layer B is older than A and younger than C </li></ul></ul><ul><li>2. Absolute Dating = actual age </li></ul><ul><ul><li>based on radiometric dating </li></ul></ul><ul><ul><li>e.g., rock layer B is 50 million years old </li></ul></ul>
  17. 17. Dating using Geological Laws <ul><li>Law of superposition </li></ul><ul><ul><li>- younger rocks are deposited on top of older rocks </li></ul></ul>younger young oldest older old
  18. 18. Grand Canyon Layers
  19. 19. <ul><li>Law of original horizontality </li></ul><ul><ul><li>- sedimentary rocks & lava are originally laid down horizontally </li></ul></ul>Roughly horizontal Dating using Geological Laws
  20. 20. A roadcut photo that I stole… WV maybe?
  21. 21. <ul><li>Law of cross-cutting relations </li></ul><ul><ul><li>rocks that intrude into other rocks are younger than their host rocks </li></ul></ul><ul><ul><li>faults are younger than the rocks they cut through </li></ul></ul><ul><ul><li>folds are younger than the rocks they bend </li></ul></ul>Dating using Geological Laws
  22. 22. Roadcut near Moab, UT
  23. 23. A B C D Events: A deposited B deposited C deposited D deposited Faulting Erosion of Surface X Erosion of Canyon But in what order? Order of Events: D deposited C deposited B deposited Faulting Erosion of Surface X A deposited Erosion of Canyon X
  24. 24. Events: A deposited B deposited C deposited D deposited E deposited F deposited G deposited Folding Erosion of Surface X Order of Events: G deposited F deposited E deposited D deposited C deposited Folding Erosion of Surface X B deposited A deposited A B C D X E F G
  25. 25. Events: A deposited B deposited C deposited D deposited E deposited F deposited Folding Faulting Erosion of Surface X Erosion of Surface Y Order of Events: F deposited E deposited D deposited C deposited Folding Erosion of Surface Y B deposited Faulting Erosion of Surface X A deposited A B C D X E F Y
  26. 26. Events: Cooling of Granite A Deposition of Sandstones B, E, & I Deposition of Shales C & H Deposition of Limestone D & F Cooling of Basalt G Folding (Tilting) Faulting Erosion of surfaces X, Y, Z Formation of mesa Order of Events: 1 . A 9 . E 2 . X 10 . F 3 . B 11 . Z 4 . C 12 . G 5 . D 13 . H 6 . fold/tilt 14 . I 7 . Y 15 . mesa 8 . fault
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