I have a polyline shapefile that is a syncline. In the Symbol Selector I'm using the syncline under the Geology 24K symbol set. But the arrows are too tiny. They're so small you can barely tell the difference between synclines and anitclines. Is there a way I can scale up the arrow size? Using ArcGIS Desktop 9.3.1.
Go to Cartographic Line Symbols/Line Properties/Line Decoration/Symbols to make the arrow symbol taller. It will not get thicker by increasing its size using this method. These symbols are just fonts.
You can experiment with adding another similar symbol (perhaps a vertical line) in a layer behind it to make it stand out even more. Keep in mind that the symbols in the palette can be rotated and offset to change their look and placement.