Aldrin learned the techniques of the Japanese color woodcut from Frank Morley Fletcher. In 1928, he studied for six months at the California School of Fine Arts in San Francisco before settling permanently in Los Angeles. That same year Aldrin made his first color woodcut and continued to experiment with the medium until 1937. Many of Aldrin's woodcuts are listed in the G.S.A. survey of WPA artworks held in Non-Federal repositories.
Aldrin’s color woodcut process often involved reworking not just a block but a scene, adding or taking away horizon lines or textures or even, on occasion, figures, but never leaving any impression without a sense of completion.
In this iteration of “California Hills,” a cool, spring landscape emerges from the paper, with trees whose greens are unfurling and a central peak in the distance nearly glowing in the late stages of shedding its wintery cobalt mantle. Aldrin uses a bold keyblock in this piece, making the scene pop forward just slightly. Other impressions may use a red palette or no outline, depending on the mood Aldrin chose to portray that day.