🔍 Key Concepts

• AHP (Above Head of Passes) river mile references on inland river charts • Common symbols on U.S. inland river charts such as gages, daymarks, and information signs • How a river gage is shown versus how aids to navigation (like daymarks) are shown

💭 Think About

• Think about which chart feature would most likely need to be referenced by an exact river mile (like 435.6 AHP) for operational reasons such as water level or clearance planning • Visualize how an information board or daymark is normally drawn—do they use a circle divided into quadrants, or do they use shapes like squares/triangles with numbers or letters? • Ask yourself which item in the choices is NOT an aid to navigation but still very important for safe river transit, and how that might be symbolized distinctly on a chart

✅ Before You Answer

• Confirm which option is specifically used to measure or indicate water level along a river • Recall that daymarks and information boards are aids to navigation and usually have numbers/letters and geometric shapes, not a circular quadrant symbol • Consider whether an electrical tower would be shown with a special circular symbol, or more likely as a structure icon with height/clearance information