146+ Amazing Facts of Earth Science
This information is a quick overview of the important concepts of the Virginia SOL's for Earth Science. If you
know these facts, then you should do well on your SOL test!
GENERAL SCIENCE & MAPPING
1. Density = mass/volume. The metric units for Density are: g/cm3 or g/ml
2. Volume for irregular objects is found by water displacement using a
graduated cylinder.
3. Warm air, water, magma etc. rises because it is less dense. Denser, cold
air, water, magma sinks.
4. As pressure increases so does density.
5. Water is most dense as a liquid. [Density = 1 g/ml] Ice floats because it
is less dense than water.
6. The instrument to measure the density of a liquid is called a hydrometer. In
less dense liquids the hydrometer will float lower, while in more dense liquids it will
float higher.
7. A hypothesis is a prediction about a problem that can be tested.
8. A variable is a changeable factor in an experiment.
9. Constants are factors that are the same.
10. Any valid scientific theory has passed tests designed to invalidate it.
Accurate results are needed to become a theory.
11. There can be more than one explanation or theory for any observation
or phenomena.
12. The altitude of Polaris equals your Latitude.
13. Latitude lines go East-West but measure North and South of the
Equator.
14. Longitude lines go North-South but measure East and West of the Prime Meridian.
15. The closer the Contour Lines, the steeper the slope.
 Contours with hash marks are depression contours
meaning the land is slopes downward.
16. Contour lines form V's and point upstream of rivers and
creeks.
PLATE TECTONICS
17. The Earth consists of a solid inner core( Fe & Ni), A liquid outer core( Fe &
Ni), a plastic- like mantle (Si, O, Fe, Ni) and a thin rocky crust (Si & O)
 The inner core of the Earth is solid iron because of intense pressure.
 Iron core produces earth’s magnetic field.
18. The lithosphere is the crust and upper mantle. Ocean Crust is thinner,
younger, & denser than continental crust.
 Oceanic crust is made of basaltic rock.
19. Similar fossils found across continents support the theory of continental drift.
20. Convection currents move tectonic plates.
 Hot material rises, cools, becomes denser and sinks.
21. Convergent Boundaries are colliding plates which cause folded or
thrust faulted mountains, subduction zones forming volcanoes &
trenches, Reverse faults are found here and caused by compression).
22. Divergent boundaries are dividing plates and cause Sea- Floor
Spreading, Mid-Ocean Ridges, Rift Valleys, & Volcanoes. Normal faults
are produced from this movement due to tension.
23. Transform boundaries slide past each other. Strike slip faults and Earthquakes are produced.
24. Earthquakes can result with any plate movement.
25. Hot Spots are not related to plate boundaries. Hawaii is a hot spot.
26. A fault is a break or crack in the Earth's Crust where movement has occurred.
27. Appalachian Mountains are folded mountains made by continental collisions..
28. Volcanic activity is associated with subduction, rifting, or sea floor spreading.
29. An Ocean plate will always sink under a continental plate because it is more dense.
30. 3 seismic stations are needed to find the epicenter of an Earthquake.
Seismometers detect earthquake waves and monitor magmatic movements in
volcanoes to predict eruptions.
31. P waves travel the fastest and reach the Seismic station first.
 travel through solids and liquids.
33. S waves reach the seismic station 2nd. They do not travel through liquids.
This is how we know the outer core of the earth is liquid.
WEATHERING & EROSION
34. Weathering is the process that rocks are broken down by water, air, and organisms.
35. Chemical Weathering occurs in warm, humid climates. Rocks compositions are changed into
new material.
36. Mechanical Weathering - breaks rocks into smaller pieces. Ex: Ice Wedging
37. Erosion is the process by which Earth materials are transported by moving water, ice, or wind.
 Gravity causes all these to happen.
38. Streams and moving water are the major agents of Erosion.
39. Deposition is the dropping or settling out of sediment. Rivers sort sediment by size however,
Glaciers deposit unsorted sediment known as till.
40. High Erosion = high relief areas
High deposition = low relief areas
41. Large particles settle out first. (gravel, sand, silt, clay)
 Sediment size from largest to smallest- breccia/conglomerate, sandstone, siltstone, shale.
42. As particle size increases, permeability (the ability to transport water)
increases.
43. Soil Evolution starts with the weathering of bedrock. Soil forms best on level
surfaces. Organic material called humus must be present in order to have Soil.
44. Soil profile consists of 3 horizons
A- Top Soil, humus (most evolved)
B- leaching from A C- Weathered Rock
A
B
C
GOUNDWATER & VA PROVINCES
45. Karst Topography has caves and sinkholes produced by acidic groundwater dissolving
limestone.
46. Valley and Ridge Province is famous for Karst topography.
47. Ground water layers from the surface down would include zone of aeration, water table, &
zone of saturation.
48. An Aquifer is a layer of rock that transports groundwater freely.
 Largest aquifer in VA is ground water filled from rain/precipitation.
49. A spring is an area where the water table reaches the land's surface which is the source of rivers.
 A delta forms at the end of the river which is similar to an alluvial fan that forms over land.
50. Hydrologic (water) cycle includes the processes of evaporation, condensation, precipitation, and
runoff.
51. The Coastal plain is the flattest area underlain by all types of sediments produced by the erosion
of the Appalachian Mountains. Fossils are abundant here.
52. Piedmont is underlain by igneous and metamorphic rocks produced by ancient volcanoes. It is
separated by the fall line from the Coastal plain.
53. Blue Ridge- oldest in the State
54. Valley and Ridge- long parallel ridges composed of folded and faulted rocks that occurred during
the collision of Africa and North America during the Paleozoic.
 Karst Topography & fossils are abundant.
55. Appalachian Plateau is underlain by sedimentary rocks. Coal resources are found here which is
the most abundant resource in VA. Fossils present.
ROCK & MINERALS
56. A mineral is found in nature, inorganic, solid, with a definite chemical composition and structure.
A gem is a valuable mineral known for their hardness. Mineral properties depend on their atomic
structure.
57. Moh’s scale of hardness refers to a mineral’s ability to resist abrasion or scratching. On a scale
from 1-10, 1 is the softest and 10 is the hardest. Harder minerals can scratch softer ones. Minerals
with a hardness greater than 5 can scratch glass.
 Calcite is a mineral that breaks into pieces of the same shape (rhomboids). That property is
called cleavage.
58. Mineral Ores are useful & profitable.
 The mineral Quartz is used in making glass and is found in the rock granite.
 Hematite & Magnetite are ores of iron.
 Galena is an ore of lead.
59. Igneous rocks are classified by composition and texture.
60. Igneous Rocks are produced by the cooling of magma or lava.
61. Fast cooling = Extrusive - Texture includes small mineral grains, glassy,
vesicular = air holes from gases. ( Pumice, Basalt, Obsidian)
62. Slow cooling = Intrusive- Texture includes coarse or large mineral grains.
(Granite)
63. Metamorphic rocks formed by heat and pressure. Pressure from colliding
plates can fold rocks and morph them.
64. Metamorphic include foliated (banded) and nonfoliated.
65. Foliated rocks are slate, schist, gneiss. Nonfoliated include marble and quartzite.
 Makes good building material.
66. Limestone morphs into marble. Sandstone morphs into quartzite.
67. Sedimentary rocks form from rock fragments, organic material, or chemical precipitation through
compaction and cementation.
68. Sedimentary are found in flat layers or strata. Fossils are found in these layers.
69. 3 types of Sedimentary rocks are
 Clastic – made from rock fragments (conglomerate, sandstone, shale)
 organic – made from plants (including phytoplankton) & animals (including seashells)
 chemical – made from dissolved minerals that evaporate or precipitate from water
70. Limestone is formed both chemically (caves) and organically (sea shells).
71. Clastic SR are made of fragments- Conglomerate, sandstone, and shale.
RESOURCES & GEOLOGIC DATING
 life has become more complex over geologic time: bacteria  fish  birds  humans
72. Virginia resources include limestone, coal, and gravel.
 Gravel is used in construction like building roads.
73. Renewable resources can be replaced by nature at a rate close to the rate at which they are
used. Includes vegetation/trees, water, wind, and soil.
74. Nonrenewable are renewed very slowly or not at all. Ex: coal, oil, and minerals.
75. The Earth's Water Supply is renewable but also finite.
76. A fossil is the remains, impressions, or other evidence of a former existence of life preserved in
rock. Can be a cast or mold.
77. Virginia's fossils are mostly marine and are from all Era's in history.
78. Law of Superposition states that the oldest rocks are found on the bottom of strata and the
youngest on top of strata.
79. Law of Cross-cutting relationships states that an igneous intrusion is
younger than the layers it cuts across.
80. Relative ages are placing events in sequence without assigning exact
numerical ages.
81. Fossils, Superposition, and Cross-cutting are used to determine relative ages.
82. Absolute time or Absolute age places a numerical age to an event.
83 .Radioactive decay or half-life is used to determine the absolute age of rocks. Rock disappears
at an equal rate.
84. Uranium dating is used to find the ages of the oldest rocks. Carbon-14 is used to find the ages of
human artifacts.
85. The Earth is about 4.6 billion years old.
86. Coal Evolution from softest to hardest- Peat, Lignite, Bituminous, Anthracite
87. Unconformities are missing rock layers usually a result of erosion.
OCEANOGRAPHY
88. 2 high tides and 2 Low tides occur each day. Earth, moon and sun align for highest high tides.
89. Tides are caused by the gravitational pull of the Earth and the Moon.
90. The salinity of the ocean is referring to the salt in the ocean. Ocean water with more salt is
denser than water with less salt. Salinity helps drive ocean currents because dense water will sink
and less dense water will rise.
 Currents move from cold to warm areas because density difference too.
 Currents move in a clockwise or counter clockwise direction because of the earth’s rotation
which is called the coriolis effect.
91. Upwelling brings cold, nutrient rich water from the bottom of ocean to the surface.
 This is rich in biological activity.
92. Estuaries are areas where salt water mixes with fresh water producing variations in salinity and
high biological activity. Ex: Chesapeake Bay
93. Sea Level rises when ice caps melt adding more fresh water into the oceans.
94. Cyanobacteria (blue-green algae) is responsible for producing the first oxygen on Earth.
 Presently Blue Green Algae is an important source of Oxygen.
 Oxygen in the oceans made the iron in ocean rocks rust.
95. The ocean is the largest reservoir of heat at the Earth's surface.
 It drives the weather of the Earth. Warm ocean water produces the energy for storms like
hurricanes and typhoons.
96. Cities that lie near water will experience different temperatures than cities that lie inland.
 Coast cities will experience medium temperatures the whole year.
 Inland cities will experience really hot temperature and really cold temperatures over the
course of the year.
97. Large bodies of water have a moderating effect on climates.
METEOROLOGY
 Weather describes day-to-day changes in atmospheric conditions.
 Climate describes the typical weather patterns for a given location over a period of many years
that is based on average rain fall and average temperatures.
98. The Dew Point is the temperature when the air is saturated with water.
99. The early atmosphere was mostly CO2 and very little O2.
100. The Earth's atmosphere is 21% Oxygen, 78% Nitrogen, and 1% trace gases.
 Mars’ atmosphere is very thin and mostly CO2
101. Human activities such as burning fossil fuels has increased CO2 levels.
102. High CO2 levels produce the Greenhouse effect.
 Venus’ atmosphere is high in CO2 so that’s why it is the hottest in the solar system.
103. CFC's are decreasing the ozone levels of the upper atmosphere
104. Areas near the Equator receive the most direct radiation.
105. Clouds form when rising air is cooled at or below its dew point and condensation nuclei are
present.
106. The Coriolis Effect causes deflections of air currents (and ocean currents) due to Earth’s
rotation.
107. A psychrometer measures humidity. A barometer measures air pressure. An Aenometer
measures wind speed.
108. High pressures are cool and dry: Low pressures are warm and rainy.
109. Wind is due to unequal cooling that causes air pressure differences. Wind blows from High
pressure to Low pressure.
Global Wind Patterns
Sea Breeze
110. The Hadley Cell involves air rising near the equator, flowing toward the North and South Poles,
returning to the surface of the Earth in the subtropics, and flowing back toward the equator at the
surface of the Earth. This produces winds called the trade winds.
111. Cold fronts move quickly and produce rain at the Front.
112. Warm fronts move slow and produce miles and miles of clouds.
113. Typically, the highest pressure is found at Sea level. Air pressure decreases with altitude.
114. Air around a High pressure moves clock-wise and outward. Sinking air produces clear skies.
115. Low pressure moves Counter- Clockwise, inward and upward.
 A typhoon is the same thing as a hurricane. They are low pressure systems that form over
warm water. Hurricanes lose energy as they move over cold water and land. The lowest
pressure in a hurricane is located in the eye.
 Tornados are rotating columns of air that occur during thunderstorm most often in the
afternoon when temperature are the warmest.
116. U.S. weather is dominated by prevailing westerlies. Weather moves west to east.
Isotherms connect lines of
equal temperatures
ASTRONOMY
117. Seasons occur because Earth’s axis is tilted 23½ o
118. Solstice is when the sun is at its most Northern or Southern Point.
 Winter Solstice is Dec. 21st (shortest day). [Southern hemisphere is tilted
away from the sun]
 Summer Solstice is June 21st (longest day). [Northern hemisphere is
tilted toward the sun]
119. Equinoxes are when the sun is directly over the equator.
 Spring March 21st and Fall September 22nd (equal hours of daylight and
night)
120. The Earth is closer to the sun in the winter.
121. The Earth rotates W to E once in 24 hours.
122. The Earth revolves CCW around the sun once in 365 ¼ days.
123. The Earth is the 3rd planet from the sun. It is special mainly because it’s the
only planet where water exist in all three states of matter (solid, liquid, gas)
123. Moon phases result from reflected sunlight and the angle at which we view
it. Half of the moon is always lit by the sun. That half always faces the sun.
 New moon – waxing crescent – 1st quarter – waxing gibbous – full moon –
waning gibbous – 3rd quarter – waning crescent
 Spring tides occur at new and full moon
 Neap tides occur at 1st and 3rd quarter moons.
124. Foucault's pendulum and Coriolis Effect prove that the Earth rotates.
125. Parallax and Seasonal constellations prove the Earth's revolution.
126. Two types of planets-- Inner (rocky) and Outer (gaseous)
 Inner planets – small, rocky, dense, few moon, short orbit periods
 Outer planets – big, gaseous, many moons, rings, long orbit periods
127. Comets are known as dirty snowballs in space and originate in the Oort
cloud.
128. Comet's tail is the result of the Solar Wind and points away from the sun.
129. Comet's coma is the result of the sun's radiation.
130. Asteroids are rocky or iron objects with origins between Mars and Jupiter.
131. AU = distance of Earth and Sun. We measure planet distances in AU's.
132. A Light Year is the distance light travels in a year. We measure star and galaxy distances with
Light years.
133. Neil Armstrong on Apollo 11 was the 1st manned landing on the moon. Sputnik was the first
satellite to orbit Earth.
134. The Big- Bang explains the origin of the Universe stating the
Universe began as an infinitely small dense sphere that expanded and
condensed into galaxies.
135. The Solar Nebula Theory explains that the sun and the planets
formed from the condensing of a giant cloud of gas and dust.
136. Our Sun's Life cycle is Nebula - protostar -Yellow Main Sequence
Star - Red Giant – Planetary nebula - White dwarf - black dwarf.
 Nebulae are clouds of hydrogen gas and dust where stars are
formed. (nebula are “nurseries”)
 A stars energy source is the fusion of hydrogen into helium
which takes place in the core.
 After a star runs out of hydrogen it will become a red giant and star fusing helium.
137. More massive stars burn through their hydrogen faster and have shorter lives than smaller stars.
 Black holes are a death stage of massive stars after it explodes as a supernova.
138. We are located in the Milky Way Galaxy, which is a spiral galaxy. So is the Andromeda galaxy.
Both are in the Local Group of galaxies.
139. The 3 types of Galaxies are grouped by shape: spiral, elliptical, and irregular.
141. The Hubble Space telescope has improved our knowledge and
understanding of the Universe.
142. Red Shifts indicate the Universe is expanding outward.
 Stars and galaxies spectrums that “red shift” mean that they are
moving away from us.
 This is used to support the Big Bang Theory.
ENVIRONMENTAL
143. Uranium power is a non renewable energy source that is cost efficient, produces little waste
and little pollution.
 However, the waste can be dangerous as well as uranium mining. Plus any accidents can be
devastating.
144. Wind power is a renewable energy source that produces no waste or pollution, and doesn’t
destroy the land.
 However, need strong winds, inefficient, no power storage, and kills birds
 A disadvantage of solar power is that it can be affected by cloud cover and is not always
available.
145. Coal mining requires forests to be stripped and destroys the land.
146. Burning coal or other fossils fuels contribute to Global Warming by releasing CO2 into the
atmosphere.
 CO2 (Carbon dioxide) is a greenhouse gas that traps heat in the atmosphere causing
temperatures to rise. It is called the greenhouse effect.
 Burning fossil fuels can also emit sulfur dioxide into the atmosphere (just like volcanoes do
when they erupt) which contributes to acid rain.
Tips to do well on your SOL's:
1. Relax; you've seen this stuff before!
2. Take your time. Read the question and all the answers. Don't leave any questions blank!
3. Try to eliminate 2 answers. This gives you a 50 - 50 chance.
4. Use your ruler to read graphics and to mark points on a graph & draw diagrams to help you visualize
questions.
5. Skip over hard questions and come back to them later. Something else in the test might give you an idea of
the answer.
6. Get good nights sleep and have a healthy dinner and breakfast before the test.
7. The most important thing is to try your best!