Sir

Martin Kemp's series on Art and Science has been very welcome and I commend Nature for bringing this issue to the attention of readers.

A couple of Kemp's articles have focused on artists who have reached outside the studio and used nature as their artistic medium; I am thinking in particular of “Turrell's tunnelling”1. Perhaps the best-known work of ‘Earth-art’ was created in 1970 by the American artist Robert Smithson (1938-73). I am referring to his monumental Spiral Jetty, a counterclockwise coil of rock and earth, 1,500 feet long and approximately 15 feet wide in the Great Salt Lake, Utah.

The spiral form is, of course, common in the natural world, such as mollusc shells; but, more importantly, the Spiral Jetty raises issues of time and scale, central theses in Smithson's work. As Smithson wrote, “each cubic salt crystal echoes the Spiral Jetty in terms of the crystal's molecular lattice. Growth in a crystal advances around a dislocation point, in the manner of a screw. The Spiral Jetty could be considered one layer within the spiralling crystal lattice, magnified trillions of times”2.

Smithson, like his contemporary Donald Judd (1928-94), had a strong interest in geology and especially the nature of geologic time.

The Spiral Jetty, now submerged, continues to evolve as it is eroded, until nothing will remain. As an ephemeral work of art it confronts time, and forces us to think about the duration, not only of art, but also of geological processes and the shaping of the geologic past.

Smithson sought an art form that could encapsulate the furthest reaches of time and space; a purist notion, indeed, but one most worthy.