Topic/Objective:______ / Full Name: ______
Class: ______Period: _____
Date: ______ / Tutor Use Only:
Essential Question:
Chapter 3: Modeling The Planet
Map:
A Map is a flat, two dimensional model or representation of the Earth’s surface.
Map Projection:
Modeling a round Earth on a flat surface produces distortion. For example, a projection that accurately represents the shapes of the continents will distort their size (example: Greenland).
  • Cartographers have developed different map projections to reduce distortion to different areas for different purposes.
Projection:
A projection is a mathematical means of transferring information from the Earth's three-dimensional curved surface to a two-dimensional map.
Mercator Projection:
Strengths:
-shows the entire world
-shows direction as a straight line which makes it good for navigation
-true shape and distances within 15 degrees of the equator
Weakness:
-great distortion of area and shape at high latitudes
Gnomonic Projection:
Strengths:
-shows the shortest distance between two points
-true shape and distance at the poles
Weakness:
-great distortion of area and shape as you move away from the center point (the lower the degree the greater the distortion)
-does not show the entire world on one map
Polyconic Projection:
Strengths:
-shows true shape and size of land masses relative to other land masses at Mid-Latitudes
Weakness:
-great distortion of area and shape as you move away from the Mid-Latitudes
-does not show the entire world on one map
Summary:
Essential Question:
Position On the Map
Every point on the map has a unique and unchangeable “address”. This is because cartographers (map makers) have established a set of lines called a parallels (horizontal lines) and meridian (vertical lines), which, together, create a grid on the Earth’s surface.
  • Parallels are also referred to as Lines of Latitude.
  • Meridians are also referred to as Lines of Longitude.
  • At its simplest, this grid divides the Earth into vertical and horizontal halves called hemispheres (def.: Half).
  • The Equator divides the Northern from the Southern Hemisphere, and the Prime Meridian divides the Eastern and the Western Hemispheres.
Latitude lines circle the Earth running (drawn) east to west.
  • Each line of Latitude forms a circle equidistant from and parallel to the Equator.
  • Latitude lines measure distance from the Equator, which has a latitude of 0 (zero) degrees.
  • The latitude of the North and South Pole is 90 degrees.
Longitude lines run (drawn) north and south between the poles.
  • Form half-circles equidistant and parallel to the each other at the equator.
  • Longitude measures distance in degrees East and West of the Prime Meridian (from 0 (zero) degrees at the Prime Meridian, up to 180 degrees).
  • The 180 degree line is a special Meridian, it is called the International Date Line.
  • Basic unit of measurement is the degree. There are times that more accuracy is needed so latitude and longitude also have minutes and seconds.
  • Example: 45o35’15”N, 75o35’15”W
All “addresses” on Earth have both Latitude and Longitude coordinates. You may, for example, be at 45 degrees North Latitude, 120 degrees West Longitude
Global Positioning System
GPS is a system of satellites and receivers that allow accurate positioning on the Earth.
  • Consists of three parts: ground control, satellites and receivers
  • Allow for determining position, speed, and distance.

Summary:
Essential Question:
Map Scale
Map scale expresses the relationship between the distance on a map and the true, corresponding distance of the same area of the Earth’s surface.
This comparison is usually shown as a ratio or fraction and is called a fractional Scale.
  • On Topographic Maps, both sides of the ratio represent the same units.
  • For example, 1:12,000 means that one centimeter of distance on the map is equal to 12,000 centimeters on the ground.
A Bar Scale, or map ruler, is a line drawn on a map of known ground length.
  • Bar Scales are useful because they allow the map reader to quickly estimate distance by laying a piece of paper next to the scale, marking the paper, and then using the paper like a ruler to measure map distance.
Map Orientation
  • Orientation is using the cardinal directions of North, South, East and West on the map and determining the same directions on the ground.
  • A compass is usually used to determine the cardinal directions on the ground.
  • A compass does not normally point to true north. Only in a few places does magnetic North and geographic North line up with each other.
  • The direction in which the compass needle points is referred to as magnetic north, and the angle between magnetic north and the true (geographical) north direction is called Magnetic declination.
  • Effects of Magnetic Declination:
Declination or Degrees off course / Error off target after 10 miles
1o / 920 feet (280 meters)
5o / 4,600 feet (1,402 meters)
10o / 9,120 feet (2,795 meters)
Summary:
Essential Question:
Topographic Maps
A topographic Map is the representation on a flat surface of part of the Earth’s surface drawn to scale.
Topographic maps show distance relationships and elevation, and help visualize Topography, or the way the land actually looks in three dimensions. Topography actually means “the shape, elevation, and slope of the land”.
  • On topographic maps different symbols and colors are used to indicate different features including bodies of water and human-made structures.
  • The color blue indicates features associated with water.
  • The color green indicates features associated with vegetation.
The color brown indicates elevation
Contour Lines
The distinctive characteristic of a Topographic Map is that the shape of the Earth's surface is shown by contour lines. They are always shown as brown lines on a topographic map.
  • Contour Lines are imaginary lines that join points of equal elevation on the surface of the land above and below a reference point, such as sea level.
  • Every point on a contour line, therefore, has the exact same elevation.
  • Contours make it possible to determine the shape of the land, measure the height of mountains, depths of the ocean bottom, and steepness of slopes.
  • Depending on the degree of elevation change that occurs in a given area, a topographic map can have few or many many on it.
  • The greater the elevation change, the more contour lines there will be on a map.
  • Contour lines can be drawn for any elevation, but to prevent a map from becoming “cluttered”, only certain elevations are drawn.
  • These elevations are chosen to be evenly spaced vertically.
  • This spacing is referred to a Contour interval, which we will discuss later.
There are several different types of contour lines on topographic maps. They are index
Contours, intermediate Contours and depression Contours.
  • Contour Lines that have elevations shown are called index Contour Lines.
  • These types of contour lines tend to be displayed on every 100 meter or foot contour line.
  • They are darker than others.
  • Contour lines that are draw between Index contour lines are referred to as intermediate Contour Lines
  • They do not have their elevations shown.
  • depression Contours are contour lines that show areas that are surrounded on all sides by higher elevations. Depression Contours have perpendicular hash marks on them. And are often circular in shape.

Summary:
Essential Question:
Contour Lines make it possible to determine the shape of the land without looking being at the location depicted on the map. Using the following Rules make it helpful in understanding the information Contour lines can tell us about an area.
Rules of Contour Lines
1. All points on a contour line are at the same elevation.
2. Contour lines are drawn at uniform vertical intervals, called the contour interval.
3. Contour lines do not cross, except at overhangs, which are rarely mapped. Contour lines may meet only at a vertical cliff.
4. The spacing of contour lines indicates the degree and kind of slope:
Closely spaced = steeper
Widely spaced = gentler
5. U-shaped or V-shaped lines indicate valleys or ridges. Contours crossing a river or gully form a V or U whose apex points uphill. Contours crossing a ridge form a V or U which points down the ridge.
6. Closed contour lines (circles or ellipses) indicate peaks.
Exception: depressions also have closed contour lines, but these lines have hash marks on them and are at the same elevation as the closest non-hachured contour.
7. Spot elevations (or bench marks, B.M.) may be marked on the map with an exact altitude. Mountain summits are very often marked in this way.
8. The difference in elevation between the highest and lowest point of a given area is the 'maximum relief' of that area.

Contour Interval

Contour Interval is the difference in elevation between adjacent contour lines.
  • Contour interval for a map is found in the legend or in the margin.
  • The contour interval is different for each map.
  • In areas with a large elevation increase, contour interval is usually larger to prevent the map from becoming cluttered with too many contour lines.
  • There are times you will be required to identify the contour interval map sections that do not show the information usually found in the map margin. (Usually when only a portion of a map is shown or the margin of the maps has been removed)
  • This is accomplished by:
  • Finding the elevations of two different Index Contours.
  • Determining the total elevation change between the two Index Contours
  • Dividing the total elevation change between the two Index Contours by the number of contour lines from one Index Contour to the next Index contour.

Summary:
Essential Question:
Slope and Elevation
Topographic maps are not just used for determining elevation. They can also be used to help visualize topography.
  • One of the most basic visualizations is Slope or Gradient.
  • Slope or Gradient refers to the change in elevation over a certain distance (rise over run).
  • On a map, this is shown as the distance between one contour line and the next.
  • High (steep) gradient or slope occurs where there is a large change in elevation over a short distance, and low (or gentle) gradients occur in areas where there is little change in elevation over a given distance (the land is “flat”).
How to determine Slope or Gradient:
  • You need to determine the change in elevation that occurs between those two points (example: if you start at 1400 feet in elevation and the end of your measurement is at 3165 feet, your elevation change is 1765 feet).
  • Then you need to determine the distance between two points (example: 2 mile).
  • Then you divide the change in elevation by the distance. (Slope = Rise/Run).
Topographic Map Profiles
Topographic map profile allows you a visual side perspective of an area so that you can see the land forms from a side view. Similar to what you would see if you were standing on the ground in that area.
Profiles are created using the following steps:
  1. Draw a line between two points on a map
  2. Using a piece of paper transfer the elevation readings (corresponding to the contour lines drawn on the map) on to the paper
  3. Then using a vertical graph paper transfer the elevation data on to the graph paper.
  4. Connect the elevations to show the profile of area along the line you drew on the map.

Summary: