KEY IDEAS

• Smithson is one of the most influential artists of the diverse generation that emerged in the wake of Abstract Expressionism and Minimalism, known as the Post-Minimalists. Although inspired by Minimalism's use of industrial materials and interest in the viewer's experience of the space around the art object (as much as the object itself), the Post-Minimalists sought to abandon even more aspects of traditional sculpture. Smithson's approaches are typical of this group; he constructed sculptures from scattered materials, he found ways to confuse the viewer's understanding of sculpture (often by using mirrors or confusing scales), and his work sometimes referred to sites and objects outside of the gallery, leading the viewer to question where the art object really resided.

• Much of Smithson's output was shaped by his interest in the concept of entropy, the second law of thermodynamics that predicts the eventual exhaustion and collapse of any given system. His interest in geology and mineralogy confirmed this law to him, since in rocks and rubble he saw evidence of how the earth slows and cools. But the idea also informed his outlook on culture and civilization more generally; his famous essay Entropy and the New Monuments (1969) draws analogies between the quarries and the strip malls and tract housing of New Jersey, suggesting that ultimately the later will also perish and return to rubble.

• Smithson's concepts of Site and Nonsite - the former being a location outside the gallery, the latter being a body of objects and documentation inside the gallery - were important contributions to the body of ideas surrounding Land art in the 1960s. His discussion of monuments and ruins in his writing also helped many to think about the purpose art might have in the landscape, after the demise of the tradition of commemorative public sculpture.