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Introduction to Maps


Map Projections. Method of turning the globe into a flat surface ... Many maps can't have one scale due to distortion. Large scale: the map closer to the ... – PowerPoint PPT presentation

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Title: Introduction to Maps

Introduction to Maps
  • Used to show unfamiliar things in a familiar way
  • Might not always look the same as the actual
  • Must behave the same as the actual thing

Reasons to use Models
  • 1. real thing is too big or too small
  • 2. real thing is too dangerous
  • 3. real thing is to expensive
  • 4. real thing is too far away
  • 5. help understnd how the real thing works (let
    you see the insides)

Map Projections
  • Method of turning the globe into a flat surface
  • No map can ever show all 4 of the following
  • 1. true direction
  • 2. true distance
  • 3. true area
  • 4. true shape

Types of Map Projections
  • Mercator
  • true direction
  • true distance along the equator
  • areas and shapes distorted, especially near poles
  • Robinson
  • true direction along all parallels and central
  • distances constnat along parallels, but scales
  • area and shapes less distorted than Mercator

Mercator vs. Robinson
  • Mercator projection
  • Robinson projection

Types of Map Projections Cont.
  • Gnomonic
  • a straight line between 2 points shows the
    shortest route between the 2 points.
  • used for planning long land, sea, or air voyages
  • badly distorted scale
  • Polyconic
  • the most accurate conical represntation
  • cone placed in contact with map

Gnomonic vs. Polyconic
  • Gnomonic Projection
  • Polyconic Projection

Coordinate Systems
  • Latitude
  • latitiude parallels that circle the world
    running east to west
  • equator is 0 degrees latitude
  • poles are 90 degrees north and south
  • one degree is divided into 60 minutes
  • latitude is a measure of distance

Coordinate systems cont.
  • Longitude
  • longitude meridians that run pole to pole going
    north and south
  • prime meridian is 0 degrees
  • international date line is 180 degrees
  • longitude is a measure of time 15 degrees 1
    hour time difference

Public Land Survey
  • developed to divide land for selling
  • each state has principal meridians and baselines
  • townships (36 sq. miles each) are numbered in
    reference to meridians and baselines
  • 36 sections (1 sq. mile each) make up each
    township, and can be further divided

Map scale
  • Ratio of distance on the map to distance on earth
  • Many maps cant have one scale due to distortion
  • Large scale the map closer to the acutal land
  • Small scale the map is more in-depth on roads,
    building, etc.

Map Type / Features
  • Maps can show many different types of
  • land use
  • roads
  • landforms
  • elevation
  • natural resources
  • political boundaries
  • topographic or contour maps

Topographic or Contour Maps
  • Rules of Contour Lines
  • a contour line connects points of equal elevation
  • contour lines do not cross
  • closely spaced contour lines represent steep
  • widely spaced contour lines represent gentle
  • contour lines V up stream valleys (they form a
    V that points upstream)
  • relief the highs and lows on the earths surface

Rules cont.
  • a closed contour line (loop) represents a hill
  • a closed contour line with hachure marks
    represents a depression
  • the contour interval is the set or established
    elevation change that happens between two
    successive contour lines