A system for mapping horizontal bores below a ground surface is provided. A transmitting source radiates a location signal from a bore. The bore may be a newly dug bore or a bore containing an existing utility. A receiver device receives a location signal and indicates, responsively to the location signal, the lateral position of the horizontal bore with respect to the receiver device. A measurement device measures the depth of the bore with respect to the ground surface at selected locations along the bore. A monitor device receives the depth data from the measurement device, compiles the depth data associated with the selected locations with respect to at least one reference position, and outputs the compiled depth data so that the depth of the bore at the selected locations may be collectively identified.