Trained as a scientist, Tony Cragg creates art that investigates the natural world. Yet if his sculptures comment on such topics as molecular structure, the human vascular system, or the Newtonian light spectrum, it is his use of man-made forms (either found or constructed) that transforms them into complex meditations on contemporary life. Here Cragg has constructed steel elements on a granite base—two smooth-surfaced concave cylindrical forms and two elemental biomorphic shapes—that comment on the Ordovician geological era of 500 million years ago, when oxygen was introduced into the atmosphere. While the oxygen gave rise to terrestrial life, it simultaneously killed off the species of algae that had produced it. The close resemblance of the cylinders to the cooling towers of nuclear power plants perhaps suggests an analogous life-death conundrum for our own technological age.