A Line Describing the Sun by William Lamson involved a day long performance in the Mojave desert in which he followed the path of the sun with a large Fresnel lens mounted on a rolling apparatus. The lens focuses the sun into a 1,600-degree point of light that melts the dry mud, transforming it into a black glassy substance. Over the course of a day, as the sun moves across the sky, a hemispherical arc is imprinted into the lakebed floor.