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75 Earth Science Facts that will help you pass the Final Exam

(these are not the only things you need to know, but they will certainly help)

1.          Independent variable is the one you change, and is graphed on the x axis.

2.          Dependent variable changes in response to changes in the independent variable, and is graphed on the y axis.

3.          Metric System uses factors of 10.  Meter for length, Gram for mass, Liter for volume
Kilo    Hecta    Deka    meter     deci    centi    milli
If converting within the metric system all you have to do is move the decimal place over

4.          Matter is defined as anything with mass and volume; therefore it has density.  The formula for density is D=m/v

5.          The same substance always has the same density.

6.          Atoms are composed of protons (positively charged particles), neutrons (neutral particles), and electrons (negatively charged particles). 

7.          Atoms with different numbers of protons are different elements.

8.          Atoms with the same number of protons, but different numbers of neutrons are isotopes of the same element.  Carbon 14 dates recent, once living objects.  Uranium 238 dates old non-living objects, such as rocks.

9.          When atoms are chemically combined they form compounds, which cannot be separated by physical means.  An example is water, H2O, or table salt, NaCl.

10.      A mixture can be separated by physical means.

11.      5 characteristics of all minerals are: it must be solid, inorganic, naturally occurring, regular repeating pattern, and a definite chemical composition.

12.      Oxygen and silicon are the two most abundant elements in the Earth’s crust.

13.      5 physical properties of a mineral are: color, luster, hardness, streak, fracture/cleavage.  Color is the least reliable.

14.      A mineral can be a rock, but a rock cannot be a mineral.

15.      Rock Cycle describes the formation of igneous, sedimentary, and metamorphic rocks.

16.      Rocks are classified by how they are formed.

17.      Magma is molten rock within the Earth; lava is molten rock on the Earth’s surface.

18.      Igneous rocks are classified by chemical composition and texture.  Igneous rock: cools fast-small crystals-mafic-extrusive-basalt; cools slow-large crystals-felsic-intrusive-granite

19.      Metamorphic rocks: banding-distorted structure caused by temperature/pressure/chemistry.

20.      Metamorphic rocks can be created from either sedimentary or igneous rocks under conditions of heat and pressure.

21.      Most of the rocks present on the Earth’s surface are sedimentary, while most of the rocks on Earth are igneous (they are below the surface).

22.      There are 3 types of sedimentary rocks; clastic (such as sandstone), chemical (such as halite), and organic (such as limestone).

23.      Sedimentary rocks may have flat layers – only rocks to have fossils.

24.      Alfred Wegener’s hypothesis of Continental Drift was based on 4 clues:  jigsaw fit of certain continents; distribution of fossils such as Mesosaurus and Glossopteris; similar distinctive rocks; and ancient climates.

25.      Plate Tectonics explains the movement of the about 30 plates.  The movement is driven by convection currents in the asthenosphere.

26.      Convection: through fluids (gases, liquids) due to density differences.  Warm rises; cool sinks

27.      Plates are made of lithosphere = crust and upper part of the mantle; and float on the asthenosphere = lower part of upper mantle. 

28.      Continental crust is thick, less dense and made of granite.  Oceanic crust is thinner, more dense and made of basalt.

29.      3 categories of plate boundaries:  converging, diverging and transform.  These are further divided by the type of crust at the boundary.

30.      Crust is destroyed at converging boundaries (subduction and collision); and created at diverging boundaries (seafloor spreading/mid-ocean ridge and rift valleys).  Examples of each.

31.      Polarity reversals – occurred when poles changed during formation of igneous rock – are evidence of seafloor spreading.  Proof that rock further away from the ridge/rift is progressively older, while new rock formed at the ridge.

32.      Trenches – indicate a subduction zone.

33.      Viscosity and trapped gases influence volcanic eruptions.  Felsic magma is thick, traps gases, more silica and more violent eruptions; Mafic magma is thinner, traps less gas, less silica and less violent eruptions.

34.      3 volcanic activities related to plate tectonics: rift eruptions (Iceland or Mid-Atlantic Ridge); subduction (Mt. St. Helens in the Cascades or Andes Mts.) eruptions; hot spots (Hawaiian volcanoes)

35.      3 volcano types:  shield, composite and cinder cone created under different conditions

36.      Focus of an earthquake is the location on the fault where stress if first released underground (movement first occurs).  Epicenter = location on the surface directly above the focus.

37.      Need 3 seismometer stations to locate an epicenter.

38.      P waves are faster than S waves which are faster than L waves.

39.      P waves travel through solids and liquids while S waves only go through solids. L waves travel only on the surface.

40.      Elastic rebound theory explains earthquakes = Stress deforms the crust until the stress is released.

41.      Time-travel graph shows the relationship between arrival times of waves and the distance that they traveled in that amount of time.  It is used to determine the distance to the epicenter from each location.  Where 3 circles representing distance traveled overlap at one point = epicenter

42.      Richter scale measures amount of energy released at the focus in magnitude 1-10, and the seismic moment measures the total amount of stress released by the entire fault also in magnitude 1-10.

43.      Fault is break in Earth’s crust where there is movement.

44.      3 types of stress produce faults: compression (pushing together), tension (pulling apart), shear (twisting)

45.      Normal fault = tensional, Reverse fault = compression; Strike-slip fault = shear

46.      Mountains form by uplift, folding and faulting.  Folded mountains created by compressional force; faulted mountains created by tensional force.

47.      Connecticut was created by “crunch and crack” of 4 terranes over the course of history.  Proto-North America is the northwest hills; Iapetos is the ancient sea which was divided by the newest terrane called Newark (the central valley); and Avalonia = eastern portion which is the remnants of Africa.  Sleeping Giant, West Rock and East Rock are all remnants of volcanic activity.  The features of the state were also carved by glaciers, which left boulders and rocks as they moved along.

48.      Uniformitarianism is concept that the present is the key to the past.

49.      Relative dating is used by geologists to determine the approximate date of rock layers using 4 laws: Superposition, Cross-cutting, Igneous Intrusions, and Included Fragments.

50.      Undisturbed layers - bottom layer is oldest

51.      Unconformity means erosion (time gap in the layers)

52.      Index fossils are good time markers (widely spread, lived a short time)

53.      Intrusion and faults are younger than the rock they are in.

54.      Weathering is the breakdown of rock, erosion is the transport of weathered materials

55.      2 types of weathering:  chemical and mechanical

56.      When a rock is broken into smaller pieces, surface area increases and weathering rate increases

57.      Water increases the rate of weathering, and must be present for chemical weathering

58.      Physical weathering occurs mostly in cold, humid climates (good for ice wedging)

59.      Water expands when it freezes – cause of ice wedging.

60.      Chemical weathering occurs mostly in warm, humid climates.

61.      Gravity causes all erosion

62.      Water is the number one agent of erosion.

63.      As particle size increases, permeability increases

64.      Capillarity increases when particle size decreases.

65.      Permeability (connection of holes); as particle size increases, permeability increases.

66.      Porosity (the amount of holes); it DOES NOT depend on particle size.

67.      Water cycle = Hydrologic cycle; evaporation – condensation – precipitation – runoff – percolation – transpiration.  Sun is the energy source to drive the cycle.

68.      Water table can be described by isolines (contour lines), and the groundwater flows perpendicular to the contour lines – in the downhill direction.

69.      Heavy, round, and dense particles settle out first

70.      Graded bedding (vertical sorting): biggest sediments are on bottom

71.      Stream deposits are sorted, round and smooth, V shaped valley.

72.      Glacial sediments are unsorted with scratches in a U-shaped valley

73.      Stream velocity depends on slope and discharge.

74.      Velocity is faster on outside of meander bend.

75.      Youthful streams have steep gradient, high speed, little to no meanders, water falls, rapids and close valley walls.  Mature streams have many meanders and oxbows, alluvial fans and deltas, low gradient, slower speed and valley walls far away.