There's a definite connection in terms of objects at hand - dealing with objects or material at hand. Pop art was very much enamored with popular imagery, and popular imagery was of course available and at hand. And land art was also using what was at hand.

I think the four land artists I showed all worked within a few years of each other. And they were standard bearers, I suppose, for land art. They each did very separate things. Apparently, later in California, a lot of artists started working in that medium and there was something of a rush of earthworks. But I wasn't involved with that.

People tend to view land art as something that happened at a certain historical moment - like minimal art, which I was also very much involved with. But it still goes on. It's very much alive.

Making the effort is quite a pleasure in itself.

I didn't know Michael Heizer until I was preparing for my "Earthworks" show in 1968, and somebody called and told me to look at his work. Heizer had already made land art before any of the others and was deeply into it. But he was very young and working out West, so I wasn't aware of his work until he came and showed it to me.

I myself had lived in the San Fernando Valley many years ago, when it was a much wilder place, and we used to go walking in the wild areas. So that early experience had a lot of similarities for me to the places that Double Negative was being done.

I opened with Edward Kienholz's The Beanery, and that's such a controversial piece that I think that brought people right away. It was a room-size work that one walked into. It was a bar with Kienholz-type figures sitting and drinking and talking - all life-size characters in a life-size setting. The exhibition was covered in Time, Newsweek, and Life, so it had huge recognition right away.