Many coastal areas of California and Oregon have emergent Quaternary marine terraces that have been assigned only indirect, approximate ages because of the paucity of suitable datable material for the U-series method, or because of the =40-ka limit of the radiocarbon-dating method. We report three thermoluminescence (TL) ages for clayey estuarine deposits from the San Simeon area of south-central California. A weighted mean TL age of 95±13 ka for clayey silt underlying marine deposits of the San Simeon (Q,) terrace suggests that this terrace correlates to oxygen isotope substage 5c (105 ka), or more likely substage 5a (80 ka). A single-analysis TL age of 230±70 ka for clayey beds in tilted estuarine deposits at San Simeon Bay is consistent with the available stratigraphic and age control for the underlying Careaga Formation (early Pleistocene or Pliocene) and the overlying Q_p marine terrace (=60 ka). This TL age most probably compares to a time of high sea level at 200±20 ka (equivalent to marine oxygen isotope stage 7). The large analytical error in this TL age is consistent with deposition shortly before or after the =200 ka highstand of sea.