Gorge Letchworth State Park

twelve intrumentalists

Robert Morris

Program Notes

Strata (1974) is scored for flute, oboe, clarinet, bassoon, trumpet, percussion, piano, two violins, viola, 'cello, and bass. It was written in 1974 on a commission from the Yale School of Music and performed that summer at Norfolk, Keith Wilson conducting the new music ensemble. As its title implies, the piece concerns itself with the transformation and interactions between and among different lines, textures and processes. It shares its germinating theme with much of my music since the mid-1970s, forging an analogy between types of musical change with natural--albeit "slow"--processes. Here terms such as "fault", "dome", "plate", "fissure" found in geology and "turbulence", "front", "stream", "jet-stream" from meteorology seem adequate enough to describe some of the types of events that occur in Strata.

Looking back on this piece thirty years later, I am struck with how many compositional innovations I packed into a piece that I wrote hurriedly in a month amid a turbulent and emotionally charged year. Many of the pitch transformations relating harmonies in the work were to form the basis of theoretical work I later published in 1983. The contrapuntal arrangement of musical lines into arrays is an early manifestation of generalized combinatoriality, which has played a central role in my music ever since. The division of the piece's duration into embedded temporal ratios was also a new direction, leading to a more holistic conception of rhythm and form.