subtly transformed into dark blues, greens, grays and blacks. His final series of paintings from the mid-1960s were gray, and black with white borders, seemingly abstract landscapes of an endless bleak, tundra-like, unknown country. Rothko, during the mid-1940s, was in the middle of a crucial period of transition, and he had been impressed by Clyfford Still's abstract fields of color, which were influenced in part by the landscapes of Still's native North Dakota. In 1947, during a subsequent semester teaching at the California School of Fine Art (known today as the San Francisco Art Institute), Rothko and Still flirted with the idea of founding their own curriculum or school. Still was considered one of the foremost color field painters – his non-figurative paintings are largely concerned with the juxtaposition of different colors and surfaces. His jagged flashes of color give the impression that one layer of color has been "torn" off the painting, revealing the colors underneath, reminiscent of stalactites and primordial caverns. Still's arrangements are irregular, jagged, and pitted with heavy texture and sharp surface contrast as seen above in 1957D1. Another artist whose best known works relate to both abstract expressionism and to color field painting is Robert Motherwell. Motherwell's style of abstract expressionism, characterized by loose opened fields of painterly surfaces accompanied by loosely drawn and measured lines and shapes, was influenced by both Joan Miró and by Henri Matisse. Motherwell's Elegy to the Spanish Republic No. 110 (1971) is a pioneering work of both abstract expressionism and color field painting. While the Elegy series embodies both tendencies, his Open Series of the late 1960s, 1970s and 1980s places him firmly within the color field camp. In 1970 Motherwell said, "Throughout my life, the 20th-century painter whom I've admired the most has been Matisse", alluding to several of his own series of paintings that reflect Matisse's influence, most notably his Open Series that come closest to classic color field painting. Barnett Newman is considered one of the major figures in abstract expressionism and one of the foremost of the color field painters. Newman's mature work is characterized by areas of color pure and flat separated by thin vertical lines, or "zips" as Newman called them, exemplified by Vir Heroicus Sublimis in the collection of MoMA. Newman himself thought that he reached his fully mature style with the Onement series (from 1948) seen here. The zips define the