Introduction to Earth Science

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Introduction to Earth Science
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First, what is Science?

• Science is a way of learning about things.
• It is the acquisition of reliable but not
  infallible knowledge of the real world including
  explanations about phenomena.

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• Science is only one approach to gaining
  knowledge.
• Science can be applied to anything that can be
  observed in the universe.
• Gather data
• Process data think about it, what is this
  data telling us?
• Classify what field of science?
• Analyzes - information draw some conclusions
• Store information - for future use to apply to
  other investigations.

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• For something to be a subject of scientific
  inquiry it must be measurable.
• We say that science is empirical
• It relies on observation and experiment.

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Earth science is the name for the group of
sciences that deals with Earth and its neighbors
in space This includes branches of geology
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• Geochemistry - The chemistry of the composition
  and alterations of the solid matter of the earth
  or a celestial body.
• Geophysics- Geology that uses physical principals
  to study properties of Earth.
• Geobiology -Studies the history of life on earth
  as well as the role the biota continue to play in
  shaping modern environments though exploring
  molecular evolution.
• Paleontology - The study of living things that
  lived in prehistoric times.
• Oceanography study of the composition and
  movement of seawater, the movement of water and
  marine life.
• Meteorology the study of the atmosphere and
  processes that produce weather.
• Astronomy the study of the universe and the
  forces that created our solar system.

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There are two broad areas of Geology Physical
Geology - examination of the materials that make
up Earth and the possible explanations for the
many processes that shape our planet. These
include mountain building forces, earthquakes,
erosion forces and volcanic forces. All these
processes create different landforms Historical
Geology tries to establish a timeline of the
physical and biological changes that have
occurred in the past.
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Earth is one of nine (oops, eight) planets that
revolve around the sun. There is an order to the
arrangement of the sun and planets. is an order
to the arrangement of the sun and planets. The
nebular hypothesis is a suggestion that the
planets and the sun formed from a huge rotating
cloud called a nebula. This nebula was formed
mostly of hydrogen and helium and a small amount
of heavier elements.
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The inner planets are relatively hot. They are
not able to hold onto the lighter gases, (H and
He). They were able to hold onto heavier gases
like CO2 and H2O. Decay of radioactive
materials caused the dense elements, like Iron
and Nickel to sink to Earths center. Lighter
rock tended to float outward towards Earths
surface. As these processes continued, gases,
which are light, escaped to Earths surface.
This gradually formed the atmosphere and the
oceans.
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A View of Earth
Earth consists of three major spheres Hydrospher
e the water portion of Earth Atmosphere the
gaseous portion surrounding Earth Geosphere the
solid portion of the Earth Biosphere the life
forms on Earth
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Water exists as solid, liquid and gas on Earth.
(the only substance that exists naturally on
Earth in all three forms) 97 of the water on
Earth is found in the oceans. Only 3 of the
water on earth is fresh water. This fresh water
is found in groundwater, streams, lakes and
glaciers.
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The gaseous envelope surrounding Earth is called
the atmosphere. It thins out quite dramatically
as we go up from the surface. 90 is found
within 16 km. It protects us from intense heat
from the sun and dangerous radiation. The
exchange of energy between space, the atmosphere
and Earths surface produce weather and climate.
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The geosphere consists of the core, the mantle
and the crust. The crust is thinnest beneath the
oceans and thickest beneath the continents. The
crust and the upper mantle form the lithosphere.
Beneath the lithosphere, the rocks are partially
molten and can slowly flow like plastic. This
region is called the asthenosphere. (A -sthenos
means without strength, or weak.) Because of
extreme pressure, the region under the
asthenosphere is rigid again. This area is
called the lower mantle.
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The biosphere includes all life on earth. It
extends from the ocean floor into the
atmosphere. Plate Tectonics Earth is dynamic.
Early Earths surface and land masses were
different from the land masses and surface very
different from what we experience today.
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• Two forces shape Earth.
• Destructive forces weathering and erosion.
  These tend to wear away and flatten.
• Constructive forces volcanism and mountain
  building. These tend to build up the surface by
  raising the land and depositing new material.
  The radioactive decay of heavy elements in
  Earths interior are the energy source for these
  forces.

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• Plate tectonics is a relatively new theory based
  on knowledge gained during the last few decades.
  The plate tectonics theory suggests that Earths
  surface is composed of individual sections called
  plates. It is the movement of these plates that
  produces earthquakes, volcanoes and forms
  mountains.

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Section 1.3, Representing Earths Surface

• Earths surface is most conveniently represented
  using some sort of global grid. These global
  grids are what we call maps.
• The global grid consists of imaginary vertical
  and horizontal lines. The vertical lines are
  called longitude lines. The horizontal lines are
  called latitude lines.
• Latitude is measured in distance north or south
  of the equator. The equator is 0 degrees.
  Longitude is measured in degrees east of west of
  the prime meridian. The prime meridian is a line
  running hypothetically through Greenwich,
  England. The prime meridian is 0 degrees. These
  grid lines allow you to locate any point of
  Earth.

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• Globes are models of the Earth. On globes
  mapmakers show how the continents and oceans
  really are. The only difference is the scale.
  Could you make a globe that would show streets in
  your community?

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Maps and Mapping

• No matter how big or small the map, there is
  always some feature that is too small, too big or
  out of place.
• A map us a flat representation of Earths
  surface. Earths features cannot be represented
  on a flat surface without distorting them.

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• The Mercator projection is a map in which the
  lines of longitude are parallel making the grid
  rectangular. The sizes and distances between
  land masses are distorted but directions are
  accurate. Mercator projections are used today.

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What is wrong with Greenland and Antarctica?
Which areas are most accurate and least distorted?
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Advantages

• Conformality - the shapes of places are accurate
• Distance - measured distances are accurate
• Area/Equivalence - the areas represented on the
  map are proportional to their area on the earth
• Direction - angles of direction are portrayed
  accurately

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• The Robinson projection show most distances,
  sizes and shapes accurately. Most of the
  distortions are toward the edges of the map.

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The Robinson Projection
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• A conic projection is made by wrapping a cone of
  paper around a globe. Points and lines are
  projected onto the paper. There is almost no
  distortion where the paper would touch the globe.
• They are useful in making road maps and for
  weather maps.

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How a conic projection shows distortion
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A Conic Projection
What happens to the maps accuracy the greater
the distance from the north pole?
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Gnomonic Projection

• Gnomonic projections are made by projecting a
  globe onto a piece of paper so that it touches a
  single point on the globes surface.
• Distances and direction are distorted but all
  lines of longitude are as spokes on a wheel.
• They are useful to navigators as they show the
  shortest distance between two points.

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Topographic Maps

• Topographic maps show elevation by means of
  contour lines.
• They show bodies of water, roads, buildings,
  political boundaries and place maps.
• They are important to geologists and hikers.

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• Elevations on the map are indicated by contour
  lines. All areas on a map along the same line
  have the same elevation.
• Every 5th line is bold and is labeled with the
  elevation. The contour interval tells you the
  difference in elevation between two adjacent
  lines. Areas with contour lines that are close
  together are steep. Areas where the contour
  lines are far apart are less steep. Steepness is
  called grade.

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The top figure shows how the heights of the hills
are translated into contour lines on a flat map.
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• Scale represents a certain amount of area on
  Earths surface translated onto a map that can be
  useful to people.
• If you want to build a scale model of a boat that
  is 20 feet long and use a scale of 1/5, the boat
  would be 4 feet long. If the scale were 1/10,
  the boat would be 2 feet long.
• Most topographic maps use a scale of 124,000.
  This means that any unit on the map represents a
  unit 24,000 times as large on Earth.

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• Geologic maps not only show contour lines but
  also give information on types of rock.

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• Satellites and computers help us create accurate
  maps with up to the minute precision. Features
  can be mapped as they are created on Earths
  surface.

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• This is called remote sensing. And can be used to
  study rivers, oceans, fires., pollution. Natural
  resources, etc.
• Satellites and computers are now used to create
  maps that are accurate and up to date.
• GPS (global positioning systems) is an instrument
  that is not only used by explorers and ships, but
  can be used in our cars to help us find our
  destination. It can tell precisely the users
  latitude and longitude.