The Quaternary climate record exhibits a structure of superimposed, aperiodic oscillations starting at the 11-yr sunspot cycle and spaced by powers of 2 in period through the major 90,000-yr glacial cycle. Climate cycles that do not fall in this structure typically correspond to harmonics of the structure oscillations. The inclusion of the known solar cycles and the presence of increased abundances of cosmogenic radionuclides at many structure periods suggest that the structure is related to long-period solar variability. ¿ 1999 American Geophysical Union