Maps Maps are model representations of a three dimensional world. Latitude and Longitude give us two dimensions Elevation gives us the third In order to fit a spherical world on a two dimensional surface maps must have some distortion.

Projections

Fields and Isolines A field is any region of space that has some measurable value at every point in that region. An isoline is a line that connects points of equal value in a field.

Type of Isolines Isotherm - an isoline for temperature Isobar - an isoline for air pressure Contour Line - an isoline for elevation

Rules for Drawing Isolines Lines must connect points of equal value Lines can not cross each other Lines can not end in the middle of the field, they must run off the edge of the field or connect with themselves

Same Latitude and Longitude Two different elevations

Features Cliffs or steep slopes –Contour lines are closer together

Features Cliffs or steep slopes –Contour lines are closer together Streams As contour lines cross a stream they point upstream

Features Cliffs or steep slopes –Contour lines are closer together Streams As contour lines cross a stream they point upstream Depressions Pits or depressions are shown by hachure lines

Do Now Define the following ters: Gradient Relief Contour interval Benchmark Isoline Index Contour Line Haschure Line