Introducing Geographic Information Systems with ArcGIS: A Workbook Approach to Learning GIS, 3rd Edition

Overlaying the Feature Classes

____ 21. Start the Union tool in ArcToolbox by selecting Analysis Tools > Overlay. For input, use Soils_with_Characteristics, Oilw_bufs, and Wagt_bufs. Call the new feature class Union_So_Ow_Wt_mpp, and, with an OK, put it in the feature data set pgdbfd_gold. After it is added to the map, examine its attribute table. How many polygons are represented? ________. What are the names of the fields you will use to extract the polygons where the gold might be? ________________, ________________, ________________. (Hint: There would be one field for each of the three feature classes in the Union.)

____ 22. Explode the multipart polygons that Union makes, using the Multipart To Singlepart tool. Call the resulting feature class Union_So_Ow_Wt. Look at its attribute table. Now how many polygons are there? _______________

____ 23. Add Getrich_County to the map. Since the gold lies within the county boundaries, you can limit yourself to the part of Union_So_Ow_Wt that lies within Getrich County. Fortunately there is a tool that will trim away the area we don’t need to look at. Use ArcToolbox > Analysis Tools > Extract > Clip. Determine by reading the sidebar Help what needs to go in each field. Give the resulting feature class the name GR_Cnty_only. Use the T/C to display that feature class by itself on the map. Use Identify to check out a number of polygons, paying attention to whether the gold might be there, based on CHARACTERISTIC, Wagt_areas, and OilwNoGold. ...