Introduction to Earth Science

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Introduction to Earth Science

• Chapter 1

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Essential Questions

1. What does an Earth Scientist study?
2. What information do various maps give to an Earth
   Scientist?
3. How do Earth Scientists (and all scientists) seek
   knowledge?

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Overview of Earth Science

• Earth science is the name of the group of
  sciences that deals with Earth and its neighbors
  in space.
• Earth science is divided into four broad
  categories

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The Earth Sciences

• Geologythe study of the solid Earth
• Oceanographythe study of the Earths oceans
• Meteorologythe study of the Earths atmosphere
• Astronomythe study of the Earths place in the
  universe

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Formation of Earth

• The Nebular Hypothesis suggests that bodies in
  our solar system evolved from an enormous
  rotating cloud called the solar nebula.
• Mostly hydrogen and helium, with some heavier
  elements.

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Differentiation

• As the newly formed Earth cooled layers formed
  through a process called differentiation.
• Denser elements (iron and nickel) sink to the
  Earths core.
• Lighter rocks and materials migrate outward
  forming the mantle and crust.

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A View of the Earth

• Earth can be thought of as consisting of four
  major spheres
• Hydrosphere
• Atmosphere
• Geosphere
• Biosphere

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Earths Major Spheres

• The hydrosphere includes all liquid water on
  Earthboth saltwater and fresh water.
• The atmosphere consists of the gaseous envelope
  surrounding the Earth.
• Although the atmosphere extends more than 100km
  up, 90 is within 16km of the surface.

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Earths Major Spheres

• The biosphere includes all life on Earth.
• The biosphere is concentrated in a zone that
  extends from the ocean floor upward several
  kilometers in the atmosphere.
• The geosphere consists of the solid parts of the
  planet and is not uniform.
• Based on differences in composition it is divided
  into three main regions, the core, the mantle,
  and the crust.

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Geosphere Divisions

• The dense core has two parts a solid inner core
  and a liquid outer core.
• The rocky mantle is divided into an lower mantle
  and upper mantle.
• The rock in the upper part of the upper mantle is
  somewhat flexible and pliableits called the
  asthenosphere (weak sphere).

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Geosphere Divisions

• The outer crust is divided into continental crust
  and oceanic crust.
• This rigid outermost layer is called the
  lithosphere (rock sphere).

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Plate Tectonics

• The lithoshpere is broken into several sections
  called plates.
• The Theory of Plate Tectonics states that
  earthquakes, volcanoes, mountain building, and
  the movement of continents are the result of the
  movement of lithospheric plates.

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Earth System Science

• Earth system science aims to study the Earth as a
  system made up of numerous interacting parts, or
  subsystems.
• A system can be any size group of interacting
  parts that form a complex whole.

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Earth as a System

• The Earth system is powered by two sources of
  energy
• The Sun which drives external processes in the
  atmosphere, hydrosphere, and at the surface.
• The Earths interior heatwhich drives plate
  tectonics.

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Each system affects the other.

• The actions of nature and people produce changes
  in all of the other parts of the Earth system.
• Resources (some renewable, some not), population,
  pollution, global warming, species extinction,
  etc. are some examples.

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Scientific Inquiry

• All science is based on two big assumptions
• The universe behaves in a consistent and
  predictable manner.
• Through study, we can understand this behavior.

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Hypothesis

• Once observations have been made and data
  gathered, scientists try to explain how or why
  things happen in the manner observed.
• They state a possible explanation called a
  scientific hypothesis.

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Theory

• Once further observations have been made and/or
  tests performed, scientists either accept,
  modify, or reject their hypothesis.
• The hypothesis is elevated to a Scientific Theory
  once it has been well tested and accepted by the
  scientific community as the best explanation of
  observable facts.

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Representing Earths SurfaceMAPPING

• Specifying a location on Earths surface is done
  using a grid system of latitude and longitude.
• Latitude is the distance north or south of the
  equator (measured in degrees).
• Longitude is the distance east or west of the
  prime meridian (also in degrees).

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The Global Grid
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Because lines of latitude never meetthey are
also known as Parallels circles around the
globe N or S of the Equator

• Each degree consists of 60 equal parts called
  minutes.
• Each minute is divided into 60 equal parts called
  seconds.

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Because lines of longitude never meetthey are
also known as Meridians semicircles running
from pole to pole.

• As with latitude, there are minutes and seconds

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Great Circle any circle that cuts the Earth into
a perfect half.

• any 2 lines of longitude directly across from
  each other on opposite sides of the globe, or
• the Equator (the only parallel of latitude that
  forms a great circle)

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Great Circle any circle that cuts the Earth into
a perfect half.
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Using Coordinates

• Both latitude and longitude are needed to locate
  positions on Earth precisely.
• When giving coordinates, latitude is always given
  first.

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• Latitude 38 8' 57" N38 degrees, 8 minutes, 57
  seconds North
• Longitude 79 4' 18" W79 degrees, 4 minutes,
  18 seconds West

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Distance

1. The distance on Earth's surface for each one
   degree of latitude or longitude 69 miles (111
   kilometers)
2. The distance between lines of latitude remains
   constant. Why?
3. What happens to the distance between lines of
   longitude as you move north or south of the
   Equator?

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Time Zones

• Earth is divided into 24 time zones
• Why 24?

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• Earth takes about 24 hours to rotate
  once on its axis (360)
• 360 24 hours 15 per hour
• Each time zone is 15 wide
• Each time zone represents a different hour

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International Date Line (IDL)

• 180 meridian
• gain or lose a day
• travel WEST across the IDL ? advance one calendar
  day (add 24 hours)
• travel EAST across the IDL ? move back one
  calendar day (subtract 24 hours)

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Why is the IDL crooked?
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Why is the IDL crooked?
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Wed. Feb. 2, 2011 030550
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Maps and Mapping

• No matter what type of map is made, some portion
  of the surface will always appear too small, big,
  or out of place.
• Cartographers (mapmakers) have found ways to
  limit the distortion of shape, size, distance,
  and direction.

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Types of Maps

• Maps are flat projections that come in many
  different forms

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Reading a Map

• Legend list of symbols and their meanings
• Scale ratio between distances on a map and
  actual distances on Earths surface
• 125,000 - one unit on the map equals 25,000
  units on Earths surface

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Map Projections

• Map projection a flat map that represents a
  3-dimensional globe

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The Mercator Projection

1. Accurate at the equator and highly distorted at
   the poles.
2. Directions accurate
3. Size and distance distorted.

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Robinson Projection

• Shows most distances, sizes, and shapes
  accurately.
• Distortions present along edges.

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Other map projections

• A conic projection is made by wrapping a cone
  around the Earth at a particular line of
  latitude. (almost no distortion at that line)
• A gnomonic projection is made by placing a sheet
  of paper on a globe so that it is touching only
  one spot.
• See page 13 in text.

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Topographic Maps

• Topographic maps show Earths elevation using
  contour lines.
• All spots along a particular contour line have
  the same elevation.

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Topographic Maps

• The contour interval on a topo map gives the user
  the difference in elevation between each contour
  line.
• Geologic Maps are those that also contain
  information about the type and age of rock
  formations in the area.

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More on maps

• All maps represent a certain area so a scale is
  included to compare actual distances.
• Satellites have made accurate cartography much
  simpler than in the past.