I'm using a mirror because the mirror in a sense is both the physical mirror and the reflection: the mirror as a concept and abstraction; then the mirror as a fact within the mirror of the concept. So that's a departure from the other kind of contained, scattering idea. But still the bi-polar unity between the two places is kept. Here the site/non-site becomes encompassed by mirror as a concept- mirroring, the mirror being a dialectic. 
The mirror is a displacement, as an abstraction absorbing, reflecting the site in a very physical way. It's an addition to the site. But I don't leave the mirrors there. I pick them up. It's slightly different from the site/non-site thing. Still in my mind it hasn't completely disclosed itself. There's still an implicit aspect to it. It's another level of process that I'm exploring. A different method of containment.
From Selected Interviews with Robert Smithson: 'Fragments of a Conversation,' edited by William C. Lipke.

1 - 3: Details from Yucatan Mirror Displacements (1–9), 1969. Nine chromogenic-development slides.
4: Mirror Displacement. Chilsea Beach, Portland Island, England, 1969.
5: Mirror Displacement (Vertical On Rocky Bank). England, September 1969.
6: Mirror Displacement (Grassy Slope). England, September 1969.
7: Mirror Displacement (Brambles). England, September 1969.
8: Mirror Displacement on Compost Heap. Dusseldorf, Germany, October 1969.
© Estate of Robert Smithson.