Hawks Crag is a prominent landmark in the Lower Buller Gorge, where the road has been cut into a cliff that drops into the Buller River. In 1955, two elderly prospectors, Frederick Cassin and Charles Jacobsen, made the first discovery of uranium on the roadside, about a kilometre downstream. The area is made up of a rock type called Hawks Crag Breccia (pronounced ‘bretcha’) – a mass of angular fragments, probably formed by floods near a mountain range where rock was being eroded rapidly. At the time it seemed a most unlikely place to find uranium, so had been overlooked by prospectors.