Geography Reference
In-Depth Information
20.
Restart ArcMap. Add North_Island_Polygons. Use the Identify tool to make sure you have
proper GIS polygons. Open the attribute table and inspect it. How many entries are there?
_______________. Dismiss the attribute table and the identify window.
Making Multipart Polygons
It turns out that several jurisdictions are involved in the chain of islands. As shown in Figure 5-12, the
land area is divided into a West County and an East County, by a north-south line that runs from 515000,
4300000) south to (5151000, 4160000). This line splits the square island. However, all inland lakes
are controlled by the Region Aqua Board. The volcano is responsibility of the Safety Board, except for its
cauldron, under the jurisdiction of the Seismic Group.
West County
East County
Region Aqua Board
Safety
Board
Seismic
Group
FIGURE 5-12 Five islands divided by county and agency
Five islands divided by county and agency
As a first step, you will split the square island, except for its lake, into two polygons.
21.
Start Editing. Use the Select features tool on the Tools toolbar to select the land part of the
square island. You should see the outer border of the island and its inner border (separating
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