Geologic maps are our most important and complete compilation of information about the solid Earth we live on, and we cannot understand the Earth without them. Meeting Challenges with Geologic Maps presents 16 examples that show how geologic maps are helping to delineate fragile habitat and ecosystems, protect against natural hazards (earthquakes, volcanic eruptions, landslides and sinkholes), and find needed resources (groundwater, metals, coal, and sand and gravel).