On bed with Michael Heizer in Munich (#1)

Circular Surface Planar Displacement Etching, New York City, 1972

Etched in baslt block in the sidewalk. Collection: Sam Wagstaff 

(Zdenek Felix, Michael Heizer, Ed. Fourcade, New York, 1979, p.19)

Related link:
On Line: Drawing Through the Twentieth Century (MoMA, 2010)

Tangential Circular Negative Line (2012)
On bed with Michael Heizer in Munich (#2)