Points of the Compass Degrees Minutes Seconds l

Points of the Compass

Degrees, Minutes, Seconds l There are 360 o degrees around a circle l Each degree can be divided into 60’ minutes l Each minute can be divided into 60” seconds

X

Global Positioning l We can use lines parallel to the equator and lines between the poles to position objects on the surface 30 o. N Lat 60 o. W Long

Latitude 90 degrees North Latitude 0 degrees Latitude (Equator) 90 degrees South Latitude

0 degrees Longitude at Greenwich, England

40 o 0’ 0”N 74 o 0’ 0”W X

Topo Maps Types of contours

500 Use the scale to measure distance UNITS MUST MATCH Contour Interval, Scale, Series, Sectors • Every point on a contour line represents the exact same elevation • Contour lines can never cross one another. • Moving from one contour line to another always indicates a change in elevation. • On a hill with a consistent slope, there always four intermediate contours for every index contour. • The closer contour lines are to one another, the steeper the slope http: //geology. isu. edu/geostac/Field_Exercise/topomaps/topo_interp. htm

Making a Topo Map • Suppose you measured elevations and positions with your GPS • Use the Latitudes and Longitudes you measured and lay out the elevations • Pick an elevation you will draw

Making a Topo Map • Pick an elevation you will draw • Find a place with two nearby elevations, one larger, one smaller

Making a Topo Map • Pick an elevation you will draw • Find a place with two nearby elevations, one larger, one smaller • Place a X where the elevation would lie

Making a Topo Map • Pick an elevation you will draw • Find a place with two nearby elevations, one larger, one smaller • Place a X where the elevation would lie • Repeat and connect the X’s

Drawing a Cross-Section (Elevation Profile) 1. Hold a sheet of paper along line 2. Mark contours 3. Write elevation next to each

• Make a vertical scale (usually exaggerated) • Make a dot at each contour at its elevation

• Connect the dots for your elevation profile • Later we will use these to make geologic cross sections • Topo Maps, Air Photo Pairs, GPS, etc