Technique 2: Manual GIS
Element 1: Making Feature Overlays
 
Materials:
            1997/1993 1:24,000 scale  San Mateo, CA / Redwood City, CA, USGS Topographic Quadrangle
            (2) 11”x 17” clear film overlay
            drafting tape
            Colored marker pens: Red, Blue, Black
 
Exercise:      

1.          Use the 1:24,000 scale San Mateo, CA / Redwood City, CA, USGS Topographic Quadrangle.
2.          Use clear film 11”x 17”overlay.
3.          Tape clear film overlay on top of 1:24,000 scale map.  Tape at the top edge.
4.          Use the Blue pen.
5.          Use the Blue pen to make four “corner marks” (tick mark ^) on the overlay, one at each corner of the study site.
6.          Trace the shoreline in Blue on the overlay.
7.          At the bottom of the overlay (in Blue) draw a short horizontal line and label beside it “1997/1993 Shoreline.”
 
                        Hint:    Use of a symbol with a short description beside it is a “key,” or means of identifying selected features.
 
8.          Remove the “1997/1993 Shoreline” overlay.
9.          Use a second 11” x 17” clear film overlay.
10.      Tape the film overlay on top of the 1:24,000 scale  San Mateo, CA / Redwood City, CA, USGS Topographic Quadrangle.  Tape at top edge.
11.      Use the Red pen.
12.      Use the Red pen to make four  “corner marks” (tick mark) on the overlay, one at each corner of the study site.
13.      Outline areas of marsh in Red on the overlay.
14.      At the bottom (in Red) draw a polygon (circle) and label it  “Marsh.”   
15.      Remove the “Marsh” overlay. 
16.      Use the third 11” x 17” clear film overlay.          
17.      Tape the clear film overlay on top of the 1:24,000 scale San Mateo, CA / Redwood City, CA, USGS Topographic Quadrangle.  Tape the top edge.
18.      Use the Black pen.
19.      Use the Black pen to make four “corner marks” (tick mark ^) on the overlay, one at each corner of the study site.
20.      Outline all mudflats on the overlay.
21.      At the bottom (in black) make a polygon (circle) and label it “Mudflat”
 
                        Hint:    Combining several single “key” items creates a “legend.” Every map should have a legend
 
22.   Tape the “Shoreline” and “Marsh” overlays one on top of each other, over the “Mudflats” overlay.  Use the four corner marks to line-up
         (“register”) the overlays on top of each other.
 
            Hint:    Tape one overlay at the bottom edge and the other overlay at the left or right edge.  By attaching the overlays at opposite edges, you can flip the overlays up and down in various alignments.