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GEO 125

Physical Geography

Methods of Location

Land survey systems (metes and bounds, Louisiana long-lot, U.S. Public Land Survey System also known as the township and range system)
Grid systems (simple grid cell systems such as those found on road maps and more complex gird systems such as the geographical grid which locates points by latitude and longitude

Importance of the earth's dimensions in formulating the geographical grid system

Dimensions of the earth (equatorial diameter, polar diameter, and equatorial circumference
Natural reference points of the earth (north pole, south pole, and the equator

Lines of latitude (also known as parallels)

Relationship with the natural reference points of the earth
Angular measurement of distance in degrees north or south of the equator
Location of the geographic north pole versus the location of the magnetic north pole
Range of lines of latitude

Lines of longitude (also known as meridians)

Importance of the Prime Meridian established at an international convention in 1884
Angular measurement of distance in degrees east or west of the prime meridian
Range of lines of longitude
International Date Line

Sample location problems using the geographical grid system

Relative location continents with regard to latitude and longitude

Great circles versus small circles

A plane passed through the outline of a great circle drawn on a globe will divide the globe into equal halves or hemispheres
The equator is the only line of latitude that is a great circle and all other lines of latitude are small circle. A small circle will divide the globe into equal halves.
All lines of longitude represent great circles
One degree along any great circle is equal to approximately 70 miles
One degree in an east or west direction along the small circles represented by 60 degrees north and south latitude is equal to approximately 35 miles

Sample distance problems using great circles