In Mark Tansey’s Purity Test , from 1991, Native Americans on horse back stand on a mountain top looking down onto Robert Smithson’s Spiral Jetty , 1970.

Judi Freedman argues in “Metaphor and Inquiry in Mark’s Tansey’s Chain of Solutions,” that “Smithson had sought to create a pure image. The Indians, unaware of the spiral’s function as a work of art, attempt to decipher it as a symbol instead.”