-53- 



APPENDIX III. MAPPING AND GRAPHIC ANALYSIS 



A primary goal of the ampping and graphic analysis of data was to 

 use a grographic inventory approach whereby each element of data would 

 be mapped at a common scale on a standard base map of the entire 

 Chesapeake Bay study area. In investigating the map resources available 

 for the Bay area, there was no existing map of the entire bay that would 

 be sufficiently detailed to portray area information such as wetlands 

 or other important natural areas. Thus, it was necessary to prepare a 

 base map by making a mosaic of the seven 1:250,000 scale U. S. Geological 

 Survey topographic maps that cover the area. 



It was decided that data should be mapped on transparent overlays, 

 to allow for manipulation and analysis, and on topographic map base 

 sheets that could be inexpensively reproduced as osalid prints. Several 

 reproducible mylar base sheets were prepared, each containing a photographic 

 copy of the map mosaic, and displaying the standard information such as 

 cities and towns, roads, topography, and water features. 



Because of the need for more detailed mapping of specific sites and 

 natural phenomena, it was necessary to prepare a sit of 1:24,000 

 scale (7-1/2 minute) USGS topographic quadrangle maps covering the study 

 area . represented on the 1:250,000 scale map. A complete set of 285 

 maps was assembled and keyed to the larger study area map by numerical 

 index. 



