What Is Earth Science
Topic I: Branches of Earth Science
A volcano erupts in Hawaii, destroying several homes and covering a major highway. An
earthquake destroys a city in Central America. A three-kilogram meteorite travels
millions of kilometers through Space and crashes through a roof of a home in Virginia.
Tornadoes weave erratic paths through the Great Plains, causing loss of life and property.
A hurricane lashes the Gulf Coast, resulting in floods and extensive coastal erosion. A
tsunami batters the coast of Indonesia, drowning thousands. As a result of heavy rains,
the Potomac River floods its banks causing flood damage in Old Town Alexandria,
Virginia.
All of these occurrences are Earth Science events. The Earth is like a very complex
machine. Each of the above occurrences impacts some “piece of the machine”, but they
do not all impact the same “piece”, nor do they impact the Earth in the same way. Earth
includes more than just the solid Earth. It also includes Earth’s oceans and atmosphere, as
well as the Universe, of which the Earth is part. Over the course of the year, you will
learn about the Earth and the processes and forces that change it, the materials from
which it is made, its long history, and its place in the Universe.
The scope of Earth is vast. Dinosaur bones on display at museums were once imbedded
in the rocks that make up some of the Earth’s cliffs and canyons. Mining certain rocks
produces some of the gold used by jewelers and dentists. Computer models simulate the
movement of the blanket of air that surrounds Earth so that scientists (meteorologists, to
be more exact) can better understand the Earth’s weather. Ocean-floor exploration has led
scientists to understand the movement of the Earth’s continents, as well as why tsunamis
occur. And, the study of objects in Space has revealed much about our own planet. As
you can see, there are many different areas of Earth Science. This broad field can be
broken into five major areas of specialization of study: Astronomy, Meteorology,
Geology, Oceanography and Hydrology.
The events mentioned above are studied by scientists who would “fit in” to one of the
above areas of specialized study. To which “branch” of study of Earth Science do the
events mentioned above belong? The volcano and earthquake are part of the discipline
called Geology, the study of the Earth’s surface and interior. The meteorite belongs to the
branch of Earth Science called Astronomy, the study of the Space. Tornadoes and the
hurricane belong to Meteorology, the study of the Earth’s atmosphere. The tsunami
belongs to the discipline called Oceanography, the study of the Ocean. The flooding
Potomac River belongs top the discipline called Hydrology, the study of the Earth’s
freshwater environments. Many, if not most, Earth Science events involve more than one
branch of Earth Science. For example, the tsunami would be studied by scientists who
study earthquakes, as well as those who study the waves caused by their occurrence in the
ocean. As was stated earlier, the Earth is a very complex machine, and no event occurs in
an isolated environment, where it does not have an impact on many different things.
Topic IA: Geology and the Activities of Geologists
Geology is the study of the origin, history and structure of Earth, and the processes that
formed it and continue to shape it, today. Geology is the study of the materials that make
up the Earth’s and the processes that form and change those materials. Geologists are
scientists who study Geology. Geologists do things such as identifying rocks, studying
the effects of glaciers, interpreting the Earth’s 4.6 billion year history. They explore
Earth’s crust to discover new sources of oil, coal, Uranium and geothermal power, as
well as other important metallic and nonmetallic minerals. They do research in
forecasting earthquakes and volcanic eruptions. They make topographic maps showing
details of Earth’s surface, and geologic maps to show Earth’s rock structure. Using data
from spacecraft, geologists can even make maps of moons and planets.
Topic IB: Astronomy and the Activities of Astronomers
Astronomy is the study of objects beyond the Earth’s atmosphere. Astronomy is a
discipline that studies objects and happenings beyond the physical reach of those who
study it. Prior to the invention of the telescope and other technology, astronomers,
scientists who study Astronomy, were only able to describe the position of objects in
Space relative to one another. Today astronomers, with the benefit of telescopes such as
Hubble, are able to study the Universe and everything in it.
Astronomers study the radiations sent out by objects in Space, and learn about the stars
and planets from these radiations. Satellites, lunar explorers and space probes have been
most useful to astronomers.
Some astronomers study the planets and their moons. Others devote all of their studies to
comets, the study the origin of the Universe, or the life cycles of the stars. Still others
work on ways of discovering whether life exists elsewhere in the Universe.
Some astronomers are fortunate to have “outer-space materials” to study. Astronomers,
as well as geologists, study meteorites that have fallen to Earth. Apollo astronauts
brought Moon rocks back to Earth. In addition satellites such as Mariner, Pioneer, Viking
and Voyager have provided many photos and observations of members of the solar
system.
Topic IC: Meteorology and the Activities of Meteorologists
Meteorology is the study of the air that surrounds our planet. Meteorologists, scientists
who study the atmosphere, study the forces and processes that cause the atmosphere to
change to produce weather. These scientists also predict the weather, and how changes in
weather might affect the Earth’s climate.
Earth’s atmosphere covers Earth’s entire surface and reaches a height of hundreds of
kilometers. The weather is created in its bottom layer. Today, jets fly above the weather,
and satellites go much higher. Therefore, scientists are very interested in all of the layers
of the atmosphere.
The meteorologists that we know best are weather forecasters. Behind these forecasters
are those that study the effects of solar energy in changing the weather. Others, do
research on hurricanes, thunderstorms and tornadoes. Still others are concerned with air
pollution, global warming, and changes in climate, which means “long-term weather”.
“Weather” describes the state of the atmosphere at a given moment.
Topic ID: Oceanography and the Activities of Oceanographers
Oceanography is the study of the Earth’s oceans, which cover nearly three-fourths of the
Earth’s surface. Oceanographers, scientists who study the Oceans, study the physical and
chemical properties of the oceans, as well as study the effects of human activity on
Earth’s saltwater bodies. An oceanographer might study the behavior of an oil spill, for
example. Oceanographers work from special research ships to measure the depth of the
Ocean and map the ocean floor. They drill into the ocean floor to study its rocks and its
history. They might attempt to locate deposits of valuable resources, such as oil. They
also track ocean currents and chart the movements of icebergs. The do research to
discover the effects of the ocean on weather and climate (El Nino). From studying
tsunamis and undersea earthquakes, oceanographers are able to develop early warning
systems for threatened coastal regions.
Topic IE: Hydrology and the Activities of Hydrologists
Hydrology, as it relates to this course, is the study of the Earth’s freshwater systems, both
on and below the surface, and the movement of this water through the water cycle
(Because Hydrology studies the movement of water through the entire water cycle,
including saltwater, Hydrology, in reality, also includes the study of the ocean component
of the Earth’s water. But, again, for this course, we will, for the most part, identify
Hydrology as the study of the Earth’s freshwater systems). Hydrologists, scientists that
study these freshwater systems, might study how to keep our streams, lakes, reservoirs,
and subsurface water supplies from being polluted, and how to clean up the water that has
already been contaminated. They might search for water supplies for cities or irrigated
farms, or work to control river flooding or soil erosion. Others might study the movement
of groundwater (water underground) to determine how best to protect the water supplies
of those who rely on groundwater (water wells).
Topic II: Earth’s Systems
A system is a group of things that are studied as a whole. For example, the mouth,
stomach, large and small intestines are part of the Digestive system. Each of the above
organs is different, yet they “operate” together for a single purpose. The Earth is made up
of many different “pieces”, yet most, if not all, of them are interactive with one another.
Scientists who study the Earth have identified five main Earth systems: the Lithosphere,
the Hydrosphere, the Atmosphere, the Biosphere and Space. Each system is unique, yet
each interacts with the others. None of Earth’s systems is independent of the others, nor
of the global system of the Earth itself.
Topic IIA: The Atmosphere
The Atmosphere is the blanket of gas that surrounds our planet. It is necessary for
respiration by most living things. It also protects life by acting as a shield against harmful
radiation from the Sun, and helps to maintain a temperature that is suitable for life. The
atmosphere contains about 78% nitrogen, 21% Oxygen and 1% water vapor, Carbon
Dioxide and trace gases.
Topic IIB: The Biosphere
The biosphere includes all living organisms on Earth, as well as the environments in
which they live. At this time, Earth’s biosphere is the only known biosphere. Scientists
have not yet found evidence of life, past or present, on other planets in our solar system,
or others. However, we have barely “scratched the surface” in this area of exploration and
discovery.
Topic IIC: The Lithosphere
The Lithosphere consists of the solid and molten layers of the Earth, and includes all of
the nonliving, inorganic material that makes up our planet (rocks, minerals and molten
material). More technically, from the perspective of the Earth’s layers, the Lithosphere is
only the solid, upper layers of the Earth’s surface and interior, but from the perspective of
Earth’s systems, the Lithosphere is all solid or molten inorganic rock-forming material
that makes up the Earth.
Topic IID: The Hydrosphere
The Hydrosphere consists all of the Earth’s water, which includes the Earth’s oceans,
seas, lakes, rivers and streams, groundwater, glacial ice and atmospheric water. 97% of
all of the Earth’s water is saltwater. The remaining 3% is fresh water contained in
glaciers, lakes, rivers and groundwater. About 75% of Earth’s freshwater is contained in
glacial ice in mountains, Iceland, Greenland and Antarctica. Most of the rest is found as
groundwater. Only a fraction of the Earth’s freshwater is in lakes and rivers.