Earth Systems Semester A Final Exam Study Guide
Chapter 1
Earth science is the name for the group of sciences that deals with Earth and its neighbors
in space.
• Geology means “study of Earth.” Geology is divided into physical geology and historical
geology.
• Oceanography is the study of the Earth’s oceans, as well as coastal processes, seafloor
topography, and marine life.
• Meteorology is the study of atmosphere and the processes that produce weather and climate.
• Astronomy is the study of the universe.
The nebular hypothesis suggests that the bodies of our solar system evolved from an
enormous rotating cloud called the solar nebula. It was made up mostly of hydrogen and
helium, with a small percentage of heavier elements.
• Shortly after the Earth formed, melting occurred in the Earth’s interior. Gravity caused denser
elements to sink to Earth’s center. Less dense elements floated toward the surface. As a result,
Earth is made up of layers of materials that have different properties.
Earth can be thought of as consisting of four major spheres: the hydrosphere, atmosphere,
geosphere, and biosphere.
• The hydrosphere is the water portion of Earth.
• The atmosphere is an envelope of gases that surrounds Earth.
• The geosphere is the layer of Earth under both the atmosphere and the oceans. It includes the
core, the mantle, and the crust.
• The biosphere is made up of all life on Earth.
Because the geosphere is not uniform, it is divided into three main parts based on
differences in composition—the core, the mantle, and the crust.
• The core, Earth’s innermost layer, is located just below the mantle.
• The mantle is 2890 kilometers thick. It is located below the Earth’s crust and above the
Earth’s core.
• The crust is the thin, rocky, outer layer of Earth.
The theory of plate tectonics provided geologists with a model to explain how earthquakes
and volcanic eruptions occur and how continents move.
• Destructive forces wear away Earth’s surface.
• Constructive forces build up the Earth’s surface.
• Tectonic plates move constantly over the Earth’s mantle.
Latitude is the distance north or south of the equator, measured in degrees. Longitude is
the distance east or west of the prime meridian, measured in degrees.
• The equator divides Earth into two hemispheres—the northern and the southern.
• The prime meridian and the 180º meridian divide Earth into eastern and western hemispheres.
No matter what kind of map is made, some portion of the surface will always look either
too small, too big, or out of place. Mapmakers have, however, found ways to limit the
distortion of shape, size, distance, and direction.
Topographic maps show elevation using contour lines.
• Atopographic map represents Earth’s three-dimensional surface in two dimensions.
• Acontour line indicates the elevation of the land.
• Acontour interval tells the difference in elevation between adjacent contour lines.
• A scale helps to determine distances on a map.
A geologic map shows the type and age of exposed rocks. Today’s technology provides us
with the ability to more precisely analyze Earth’s physical properties.
• Satellites and computers provide more accurate maps.
Earth System Science
Earth system science aims to understand Earth as a system made up of interacting parts,
or subsystems.
A system can be any size group of interacting parts that form a complex whole.
• In a closed system, matter does not enter or leave the system.
• In an open system, energy and matter flow into and out of the system.
• Most natural systems are open systems.
• The Earth system is powered by energy from two sources.
One source of energy for Earth systems is the sun, which drives external processes that
occur in the atmosphere, hydrosphere, and at Earth’s surface.
• The sun’s energy drives weather, climate, ocean circulation, and erosion.
Earth’s interior is the second source of energy for Earth systems.
• Heat powers the internal processes that cause volcanoes, earthquakes, and mountains.
• The Earth system’s processes are interlinked. A change in one part of the system can affect the
whole system.
Our actions produce changes in all of the other parts of the Earth system.
• Environment refers to things that surround and influence an organism.
• Environmental science focuses on the relationships between people and Earth.
• Resources include water, soil, metallic and nonmetallic minerals, and energy.
Renewable resources can be replenished over relatively short time spans.
• Plants, animals, and energy such as water, wind, and the sun are some examples of renewable
resources.
Although these and other resources continue to form, the processes that create them are so
slow that it takes millions of years for significant deposits to accumulate.
• Iron, aluminum, copper, oil, natural gas, and coal are examples of nonrenewable resources.
• Population growth equals an increase in demand for resources.
Significant threats to the environment include air pollution, acid rain, ozone depletion, and
global warming.
• Understanding Earth’s environment and the impact of humans on limited resources is
necessary for the survival and well-being of the planet.
Once data have been gathered, scientists try to explain how or why things happen in the
manner observed. Scientists do this by stating a possible explanation called a scientific
hypothesis.
• A hypothesis becomes a scientific theory if it survives tests and analyses.
A scientific theory is well tested and widely accepted by the scientific community and best
explains certain observable facts.
• Scientific investigations often have four steps—collecting facts; developing a hypothesis;
observing and experimenting; and accepting, modifying, or rejecting the hypothesis.
The Biogeochemical Cycles
 Carbon makes up the basis for all organic life
 Most nitrogen is unusable in the atmosphere; we all depend on bacteria to “fix” it for us
 Phosphorus does not cycle through the atmosphere
 Long-term part of each cycle includes forming and eroding rock; whereas the short-term
part of each cycle is the movement between living things
The major reservoir (storage) of carbon is carbon dioxide (CO2) in the atmosphere.
Carbon In the atmosphere
Carbon dioxide (CO2)
Carbon In living things
Glucose (C6H12O6) or sugar/carbohydrates, fats, proteins
Carbon Underground
Rocks (limestone) and fossil fuels, ex. coal, oil, natural gas
Where is nitrogen found?
 The major reservoir of nitrogen is the atmosphere as nitrogen gas (N2)
Important processes that cycle nitrogen into living organisms:
 Nitrogen fixation - Bacteria that live on roots of legumes (bean plants like soybean or
clover) convert atmospheric N2 to a “fixed” form that plants can absorb
 Absorption
 Heterotrophy (food chain) - As organisms consume food, nitrogen travels from one
organism to another is used to make proteins
Processes that cycle nitrogen out of living organisms:
 Excretion
 Decomposition
 Denitrification
Where is phosphorus found?
 The major reservoir of phosphorus is in salts & rock sediment
 Other reservoirs include waterways (washed from eroded rocks and emptied in oceans)
How phosphorus cycles into living organisms:
 Erosion of rocks
 Absorption
 Heterotrophy (food chain)
Short-term
 Absorption & decomposition
Long-term (always think the “rock cycle”)
 Phosphorus cycle mainly involves reserves underground and on the bottom of the ocean
 Most nitrogen is unusable in the atmosphere; we all depend on bacteria to “fix” it for us
 Phosphorus does not cycle through the atmosphere
 Long-term part of each cycle includes forming and eroding rock; whereas the short-term
part of each cycle is the movement between living things
Sulfur Cycle
A hydrothermal vent is a hot spring on the ocean floor, found mostly along
mid-oceanic ridges, where heated fluids exit from cracks in the earth's crust. Iron, sulfur, and
other materials precipitate from these waters to form dark clouds. Also known as a black smoker
which occur along mid-oceanic ridges.
Oxygen Cycle
Earth has an unusually high concentration of oxygen gas. The reason is the oxygen cycle. There
are three main oxygen reservoirs on Earth: The atmosphere, The biosphere, The geosphere
Photosynthesis is the main driving factor for the oxygen cycle. Without photosynthesis Earth's
atmosphere would be very different - not supporting life as we know it. Photosynthesis produces
oxygen which rises into the atmosphere. Respiration chemical reactions remove oxygen from
the atmosphere.
* A large portion of the Earth’s oxygen is found in rocks.
Origins of Earth and our Solar System:
Know difference between aphelion & perihelion; apogee & perigee; geocentric & heliocentric; rotation vs.
revolution; umbra/penumbra, solar vs. lunar eclipses; Length of time for moon phases; KNOW all 8 phases!!
*Surface features of the moon: rays, craters, rilles, regolith, lunar highlands, maria
*theory of moon formation
The elements of the earth separated (differentiated) into the molten iron core at the center and the lighter silicate
rock towards the surface.
The present atmosphere of the Earth is very different from the original atmosphere.
The boundary between the mantle and outer core is detected due to significant density differences; called the “D”
layer. The moho is the density boundary between the crust and mantle.
Mantle convection distributes heat through the mantle and is the mechanism that drives plate tectonics.
The present day heat flux of the Earth is only 20% of what it was originally.
The center of the nebula became the sun. The terrestrial planets formed closer to the sun at higher temperatures,
and the Jovian planets formed further away under much colder temperatures.
Know the three stages of planetary formation.
The asteroid belt lies between Mars and Jupiter.
Be able to identify the crust, upper mantle, lower mantle, outer core, and inner core on a diagram.
Continental crust has an average composition of granite; oceanic crust is composed primarily of basalt.
Know the major distinguishing characteristics of each of the planets in our solar system.
Know the major characteristics of terrestrial planets vs the Jovian planets.
The Earth’s core is made of what?
What is accretion? Accretion can explain what planetary characteristics?
Formation of the oceans and initial atmosphere began by volcanic outgassing.
What is a comet? Know the differences between meteor, meteoroid, and meteorite.
Most of the information about Earth’s interior was obtained by studying seismic waves. S-waves in particular, do
not travel through liquids, and do not travel through the outer core.
Two sources of heat within the Earth are: residual heat from gravitational contraction from the early Earth, and
the 4 radioactive elements U-235, U-238, K-40, Th-232.
Plate Tectonics
Plate Tectonic Theory – The Earth’s outer shell (lithosphere) is composed of rigid plates that are
moving relative to one another.
What moves the Plates? Slab Pull and Mantle Push
Divergent Plate Boundaries aka Mid-ocean Ridges - Where Oceanic Crust is Made!
2 Types: Mid
oceanic ridges and continental rifting.
Basalt – Rock Type of the Oceanic Crust - Remember: Melting the mantle makes mafic magma!! Always!
Continental Rifting The creation of new ocean basins; tearing a continent apart: East African Rift Valley
Divergence: To split apart. Associated with Normal Faulting. Deformation by tension: occurs at plate
boundaries and locations of where upwelling mantle stretches the lithosphere.
Crust stretches and thins by brittle normal faulting in upper crust and plastic flow in lower crust.
Convergent Boundaries - Where the Action Is!!
Consequences of Convergence: Explosive Volcanism, Mountain Building &
Rock Deformation, Earthquakes
Three (3) Types of Convergent Boundaries:
1) Ocean-Ocean convergence: The Aleutian Islands, Alaska; Japan, etc.
2) Continent-Ocean Convergence: Volcanic Arc Mountain Ranges; Example: The Andes Mountains,
South America; Cascade Range (Mount St. Helens) in Oregon and Washington state.
3) Continent-Continent Convergence: Mountain Building; Example: The Himalayas, India
Transform Boundaries -What are they?
Examples: San Andreas Fault in Calif.
Mantle Hotspots Creation of over-thickened oceanic crust. Form islands that appear in the middle of a
tectonic plate, not associated with a plate boundary. An example is the Hawaiian Islands.