Models of the earth
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Models of the Earth. Earth. Very nearly perfect sphere No top, bottom or sides Earth’s axis of rotation can be used to establish reference points Reference points: North and South poles Equator divides earth into northern and southern hemisphere. Latitude. Parallels-

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  • Very nearly perfect sphere

    • No top, bottom or sides

  • Earth’s axis of rotation can be used to establish reference points

  • Reference points:

    • North and South poles

    • Equator divides earth into northern and southern hemisphere


  • Parallels-

    • describes north and south of the equator

    • Run east-west parallel of the equator

  • Latitude

    • Angular north or south of the equator

Degrees of latitude
Degrees of Latitude

  • Measured in degrees

  • Equator is 0°

  • North Pole and South Pole is 90°

  • Each degree consists of 60 equal parts called minutes

    • 1.85 km

    • Symbol is ‘

  • Each minute is divided into 60 equal parts called seconds

    • Symbol is ‘’


  • Meridian

    • is a semicircle that runs from pole to pole

    • Prime meridian is 0°

  • Longitude-

    • is the angular distance east or west of the prime meridian

Degrees of longitude
Degrees of Longitude

  • All locations have a longitude between 0° and 180° east or west of the prime meridian

  • A degree of longitude equals approximately 111 km

    • Decreases as you move towards the pole

Great circle
Great Circle

  • Any circle that divides the glove into halves or marks the circumference of the globe

    • Any circle formed by two meridians of longitude that are directly across the globe from each other is a great circle

    • Can run in any direction around the globe

    • Air and sea routes often follow great circles

Finding direction
Finding Direction

  • Use a magnetic compass

  • Geomagnetic poles- areas of earth’s surface above where the poles of the imaginary magnet

  • Needles of compass points to geomagnetic north pole

Magnetic declination
Magnetic Declination

  • Angle between the direction of the geographic pole and the direction in which the compass needle points is called magnetic declination.

  • Measured in degrees east or west of the geographic north pole

Gps global positioning system
GPS (Global Positioning System)

  • GPS can be used to find their location on earth

  • Based on a global network of 24 satellites that transmit radio signals to Earth’s surface.

  • First one was NAVSTAR (launched in 1978)

  • Can be accurate within 10-15 meters of position


  • Globe- model of earth

    • Accurately represent locations, relative areas, and relative shapes

    • Useful for large surface features

    • Too small to show details of earth’s surface

Making maps
Making maps

  • Cartography

    • Scientists who make maps

    • Collect data by a field survey or remote sensing

  • Remote sensing

    • The process of gathering and analyzing information about an object without physically being in touch with the object

Map projections
Map projections

  • Map is a flat representation of Earth’s curved surface

  • Area may be distorted in size, shape, distance or direction

    • Map of a city shows slight distortion

    • Map of earth shows greatest distortion

  • Map projection

    • A flat map that represents a spherical surface

Cylindrical projections
Cylindrical Projections

  • Meridians appear as straight, parallel lines that have an equal amount of space between them

  • Advantage:

    • Parallels and meridians form a grid (locating positions is easier)

Azimuthal projections
Azimuthal Projections

  • Place a sheet of paper against a transparent, lighted globe so that paper touches the globe at only one point

  • Great for air travel and finding great circles

  • Little distortion at point of contact

  • Unequal spacing between parallels causes distortion in both direction and distance

Conic projections
Conic Projections

  • Made by placing a paper cone over a lighted globe so that the axis of the cone aligns with the axis of a globe.

  • Touches the globe at a parallel

  • Where the cone and globe are in contact have the slightest distortion

Reading a map
Reading a Map

  • North on top, east on the right, south on the bottom, west on the left

    • Never Eat Soggy Waffles

  • Parallels run from side to side

  • Meridians run from top to bottom

  • Legend- a list of map symbols and their meanings

Map scales
Map Scales

  • Scale- the relationship between the distance shown on a map and the actual distance

  • Graphic Scale- Printed line that has markings on it that are similar to those on a ruler

  • Fractional Scale- 1:25,000 (one unit of distance represents 25,000 of the same unit on earth

  • Verbal Scale- Sentence form (One cm is equal to one km)


  • A line on a map that represents a constant or equal value of a given quantity

  • Meteorologists use to show atmospheric pressure

Topographic maps
Topographic Maps

  • The size and shape of the land surface features of a region including its relief

  • Natural features

  • Shows elevation

    • The height of an object above sea level

Topographic maps1
Topographic Maps

  • More detailed information about the surface

  • Shows size, shape and elevation

  • Contour lines- a line that connects points of equal elevation on a map (is an isogram)

  • Relief- the difference between the highest and lowest elevations in a given area

Topographic maps2
Topographic Maps

  • Widely spaced contour lines indicate gradual change in elevation

  • Closely spaced contour lines is a rapid change in elevation

  • Contour lines that bend to form a V is a valley

  • Closed loop contour lines indicate a hilltop

Topographic maps3
Topographic Maps

  • Buildings, boundaries, roads, and railroads- normally in black

  • Major highways-red

  • Bodies of water-blue

  • Forest-green

  • Contour lines- brown and black

Geologic maps
Geologic Maps

  • Show distribution of geologic features

  • Types of rocks, locations of faults, folds, etc.

Geologic maps1
Geologic Maps

  • Geologic unit- volume of rock of a given age range and rock type

  • Assigned by color

  • Letters represent age

    • One capital letter- symbolizes age of rock

    • Lowercase letters- represent the name of the unit or type of rock

Geologic maps2
Geologic Maps

  • Contact lines-indicates places at which two geologic meet

  • Strikes-indicates direction in which beds run

  • Dips- Indicates the angle at which the beds tilt

  • Two types of contacts

    • Faults- cracks where rocks can move past each other

    • Depositional contacts-show where one rock layer formed above another

Soil maps
Soil Maps

  • Classify, map and describe soils

  • Based on soil surveys

  • NRCS (Natural Resources Conservation Service maps soil

Soil maps1
Soil Maps

  • Soil Survey

    • Text- general information about the geology, topography and climate of area being mapped

    • Tables- describes and volumes of soils in the area

    • Maps-

      • General map shows the approximate location of different types of soil within the area

      • Detailed information about soils

  • Uses- agricultural and land management