Throughout this apogee of avant-garde work, Takemitsu's musical style seems to have undergone a series of stylistic changes. Comparison of "Green" (for orchestra, 1967) and "A Flock Descends into the Pentagonal Garden" (1977) quickly reveals the seeds of this change. The latter was composed according to a pre-compositional scheme, in which pentatonic modes were superimposed over one central pentatonic scale (the so-called "black-key pentatonic") around a central sustained central pitch (F-sharp), and an approach that is highly indicative of the sort of "pantonal" and modal pitch material seen gradually emerging in his works throughout the 1970s. The former, "Green" (or "November Steps II") written 10 years earlier, is heavily influenced by Debussy, and is, in spite of its very dissonant language (including momentary quarter-tone clusters), largely constructed through a complex web of modal forms. These modal forms are largely audible, particularly in the momentary repose toward the end of the work. Thus in these works, it is possible to see both a continuity of approach, and the emergence of a simpler harmonic language that was to characterise the work of his later period.