As far as completing your geologic map goes, you will be keen to know what
other information is necessary to show on the map. Because things could get cluttered
fairly quickly by adding new map layers, you will naturally want to limit the
number of map layers as much as possible while still providing the necessary interpretive
information. To that end, you may want to include hydrography, which, since
it is a linear feature type, does not threaten to clutter the map very much. The main
purpose of adding a hydrography layer is to aid in a viewer’s understanding of geologic
features since rivers and streams often follow geologic fracture lines.