Thursday, November 17, 2016

99 Geological/Earth Science Facts

My 9th grade Earth Science teacher and friend Chris Visco, had put together a list of 99 Earth Science facts (or as he put it, the "99 ways to pass the Earth Science Regents"). I thought they were very well thought out and provided a ton of basic Earth science information so I figured I would pass them on to you.


  1. The true shape of the earth is an oblate spheroid.
  2. The earth's true shape is most easily confirmed by photographs from space
  3. The earth appears to be perfectly round
  4. Compared with its size, the earth's surface appears to be smooth
  5. To determine the circumference of the earth, you need to measure the altitude of a star above the horizon from two or more locations
  6. The earth's equatorial circumference is slightly larger than its polar circumference
  7. The lithosphere is the earth's solid outer layer of rock
  8. The hydrosphere is the thin layer of water on the earth's surface
  9. The atmosphere is the thin shell of gases surrounding the earth
  10. The densest sphere is the lithosphere
  11. The least dense sphere is the atmosphere
  12. The thickest sphere is the lithosphere
  13. The thinnest sphere is the hydrosphere
  14. Over time, elevations represented on a topographic map change
  15. The building blocks of rocks are minerals
  16. Minerals are identified on the basis of well-defined physical and chemical properties
  17. Minerals are grouped into families according to their chemical composition
  18. The basic unit of most minerals is the silicon-oxygen tetrahedron (pyramid shape)
  19. The physical properties of minerals depends upon the arrangement and bonding of their atoms
  20. Rocks are classified on the basis of their origin (bow they formed)
  21. Igneous rocks form by the crystallization of molten magma or lava
  22. Crystal size in igneous rocks depends on rate of cooling
  23. Intrusive igneous rocks form slowly beneath the earth's surface
  24. Extrusive igneous rocks form quickly on the earth's surface
  25. Continents are granitic, Oceans are basaltic
  26. Sedimentary rocks form from sediments, evaporation of water, and organic remains
  27. Sedimentary rocks form at or near the surface of the earth
  28. Fossils are found almost exclusively in sedimentary rocks
  29. Metamorphic rocks form from other rocks by the action of beat and or pressure
  30. Contact metamorphism occurs when molten rock comes in contact with surrounding rocks
  31. Regional metamorphism occurs over large areas and is associated with mountain building
  32. Earthquakes and volcanoes occur in specific zones (ring of fire, mid atlantic) ·
  33. The speed of a seismic wave depends on the density of the material thru which it travels
  34. Richter and Mercalli measure the strength of an earthquake
  35. The Richter scale gives the power released
  36. The Mercalli scale gives the damage caused
  37. Plate tectonics the earth's crust is divided into pieces called plates which move
  38. The three types of plate boundaries are divergent (moving way, mid ocean ridge), convergent (coming together) and transform (sliding)
  39. Subduction is when one plate sinks under another forming a trench
  40. Weathering occurs when rocks are exposed to the hydrosphere, biosphere, and atmosphere
  41. Moist and warm climates favor chemical weathering
  42. Moist and cold climates favor physical weathering
  43. Weathering is slow in dry climates
  44. As particle size decreases surface area increases and the rate of weathering increases
  45. Soils develop as a result of weathering and biological activity
  46. The primary force that drives the agents of erosion is gravity
  47. The most important agent of erosion is running water
  48. The amount of stream erosion depends on the velocity of a stream and the volume of water
  49. Stream velocity depends on gradient and volume of water
  50. The outside of a meander bend is fast and erodes. The inside of a meander bend is slow and deposits
  51. As stream velocity increases, the size of the particles that can be transported increases
  52. Streams carry sediments by solution, suspension, bouncing and rolling
  53. The particles that settle out first are larger, most dense, and roundest
  54. Water and wind deposits are sorted by size and layered
  55. Gravity and glacial deposits are unsorted
  56. Arid landscapes are angular. Humid landscapes are smooth
  57. Glacial landscapes show U shaped valleys, depressions, irregular hills, scratched boulders
  58. In undisturbed sedimentary rocks, the bottom layer is the oldest
  59. Faults, folds, and intrusions are younger than the rocks they are found in
  60. Index fossils are found over a wide area and existed for a short period of time
  61. Geologic time is divided into units based on the fossil record
  62. An unconformity is a buried erosional surface
  63. Unconformities represent a gap in the geologic record
  64. Radioactive isotopes decay at a predictable rate known as half 1ife
  65. Carbon is used to date recent, organic remains
  66. Most life forms of the geologic past have become extinct
  67. As temperature increases, relative humidity decreases
  68. As altitude increases, air pressure decreases
  69. Wind is named for the direction it comes from
  70. The closer air temperature is to the dew point the greater the chance of precipitation
  71. Air in a low pressure area is warm and moist
  72. Air in a high pressure area ls cool and dry
  73. A rising barometer indicates good weather coming. A falling barometer indicates bad weather coming. A steady barometer indicates no change
  74. Fronts occur where air masses of different temperature and humidity meet
  75. The most likely areas for precipitation are the leading edges of air masses (fronts)
  76. The circulation in a low pressure system is counterclockwise, toward the center, where air rise. The circulation in a high pressure system is clockwise, away from the center, where air sinks.
  77. Weather systems in the U.S. usually move from west to east
  78. cT warm & dry.  cP cool & dry. mT warm & moist. mP cool & moist
  79. Hurricanes form over warm oceans ln summer and autumn
  80. Tornadoes form in the spring where very different air masses collide
  81. Hurricanes lose strength as they move over land or cool water
  82. The earth rotates west to east, 15 degrees per hour, in 24 hours or in one day
  83. In the U.S. the sun appears to rise in the east, move through the southern sky and set in the west
  84. The earth revolves counterclockwise, 1 degree per day, in 365 ¼ days or one year
  85. As a planet gets closer to the sun the faster it orbits
  86. The earth’s orbit around the sun is nearly circular
  87. The moon revolves around the earth, in an elliptical orbit, in approximately one month
  88. The seasons are caused by the tilting of the earth’s axis and revolution around the sun
  89. The intensity of sunlight varies with the angle of the sun above the horizon
  90. The sun is most intense at an angle of 90 degrees
  91. Shadows get longer as the sun gets lower ln the sky
  92. Summer solstice: June 21.
    1. The sun rises north of east.
    2. The sun sets north of west.
    3. The sun reaches highest altitude of year.
    4. Vertical ray hits tropic of cancer.
    5. NY gets approx. 16 hours of daylight.
    6. North pole gets 24 hours daylight
  93. Winter solstice: December 21
    1. The sun rises south of east
    2. The sun sets south of west
    3. The sun reaches lowest altitude of year
    4. Vertical ray hits Tropic of Capricorn
    5. NY gets approx. 8 hours daylight
    6. North pole gets 0 hours daylight
  94. Equinoxes: Vernal March 21, Autumnal September 22
    1. The sun rises due east
    2. The sun sets due west
    3. Vertical ray hits equator
    4. The whole earth gets 12 hours daylight
  95. The equator always receives 12 hours of daylight
  96. The earth absorbs mostly short wavelength light energy. The earth reradiates mostly longer wavelength heat radiation
  97. Gases such as carbon dioxide prevent the escape of heat causing the greenhouse effect
  98. Marine climate cool summers, warm winters. Continental climate cold winters, hot summers
  99. Leeward side of a mountain dry & warm due to compression
  100. Windward side of a mountain cool & moist due to expansion

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