Intro to Maps Since most of you purchased your lab books today, I’ll give this little introduction Normally you are expected to study the lab before coming to class

Points of the Compass

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

X

Global Positioning 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

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

0 degrees Longitude at Greenwich, England

X 40 o 0’0”N 74 o 0’0”W

Topo Maps Types of contours

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 are always four intermediate contours for every index contour. The closer contour lines are to one another, the steeper the slope Contour Interval, Scale, Series, Sectors Use the scale to measure distance UNITS MUST MATCH

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