[2] His father, a Department of the Interior employee, moved the family to Blackfoot, Idaho[3] and eventually to San Francisco, where the young Hammersley first took art lessons.

During this period, Hammersley met Pablo Picasso, Georges Braque and Constantin Brâncuși, visited their studios,[1][6] and made sketches.

[1][2][6] Hammersley first gained widespread acclaim when his paintings were featured in the landmark Four Abstract Classicists exhibit, which also showcased the work of Karl Benjamin, John McLaughlin, and Lorser Feitelson.

[1] This 1959 exhibit was organized by the Los Angeles County Museum of Art and curated by Jules Langsner, who, with Peter Selz, coined the term "hard-edge painting" to describe the work of these artists.

Los Angeles Times art critic Christopher Miles wrote that "they show Hammersley to have been, from the start, as keen a student of Modernist style as he was of color and composition.

The triangles, squares, and other geometric shapes combine to form interlocking relationships to each other, creating a rhythmic composition with interchangeable positive and negative space.

These works, produced in 1964 and from 1982 into the 2000s, also contain interlocking shapes, but, as Miles wrote, they "are more evocative and suggestive, with elements seeming to probe and penetrate, embrace and envelop one another.

Another savvy and refreshing move Hammersley makes is to counter the clean, impersonal precision of hard-edge painting with the amusing presence of his own personality, his own hand.

By reinforcing a connection to the familiar world of touch, the frames also scuttle the notion that abstraction belongs to a rarefied superstratum of experience.

[10]Art critic David Pagel commented that the complex arrangements of colors and geometric shapes in some paintings featured in a 2002 show made Hammersley "look like a Baroque artist in Minimalist clothing.