If it can be said that Marcel Duchamp is the grandfather or great grandfather of Conceputal Art, and Yves Klein it's father, then Robert Smithson must, at the very least be it's first practitioner. It is Smithson's work that the label of Conceptual Art was coined for - perhaps more than any other. Smithso was directly involved in the 'Land Art' movement of the late 60s to mid-70s, whose other players included Walter De Maria, Michael Heizer, Mary Miss, etc... though Smithson's interest always seemed to oblique to the concerns of the others in this group - often making internal references where the others were 'external'. A prime example of this is his Mirror Displacement series. While the mirrors themselves reflect an image of their environment and of the sun, what is clear and distinct from the others' work is their objecthood and their formal arrangement independent of the space of their surroundings. Smithson confirmed this by moving some of these relationships into the art gallery .

Robert Smithson - Ithaca Mirror Trail, 1969.

Spiral Jetty - Aerial Photograph

Antarktis Circular Map, 1967