In a 1922 monograph on the California chaparral, William S. Cooper called attention to some patches of chamise (Adenostoma fasciculatum) growing robustly on deep alluvial soils on the west side of the lower Sacramento Valley. He submitted that these patches were relicts of “the true regional climax,” suggesting that centuries of Indian burning accounted for the prevalence of grass instead of brush when the Sacramento Valley was first seen by Europeans. We examined available historical evidence and found that Cooper was right in concluding that the chamise patches he saw were vestiges of a much more extensive (ca. 4000 ha) aboriginal stand. Whether the controlling local influence was edaphic or anthropogenic, and whether the local pattern had any wider regional implications, are questions that remain open to speculation.