Noun
land art (uncountable)
Artworks created from, and sited within, the natural environment.
Likely, these artworks could have been created and installed in the vein of the Earth Art (Land Art) Movement which emerged in the 1960s and 70s. Source: Internet
This theory seems to be far more plausible as similar artworks and objects had emerged in the Land Art Movement which was on its peak during the 1960s-70s. Source: Internet