Quantifying the marine radiocarbon reservoir effect, offsets (ΔR), and ΔR variability over time is critical to improving dating estimates of marine samples while also providing a proxy of water mass dynamics. In the northeastern Pacific, where no high-resolution time series of ΔR has yet been established, we sampled radiocarbon (14C) from exactly dated growth increments in a multicentennial chronology of the long-lived bivalve, Pacific geoduck (Paneopea generosa) at the Tree Nob site, coastal British Columbia, Canada. Samples were taken at approximately decadal time intervals from 1725 CE to 1920 CE and indicate average ΔR values of 256 ± 22 years (1σ) consistent with existing discrete estimates. Temporal variability in ΔR is small relative to analogous Atlantic records except for an unusually old-water event, 1802–1812. The correlation between ΔR and sea surface temperature (SST) reconstructed from geoduck increment width is weakly significant (r2 = .29, p = .03), indicating warm water is generally old, when the 1802–1812 interval is excluded. This interval contains the oldest (–2.1σ) anomaly, and that is coincident with the coldest (–2.7σ) anomalies of the temperature reconstruction. An additional 32 14C values spanning 1952–1980 were detrended using a northeastern Pacific bomb pulse curve. Significant positive correlations were identified between the detrended 14C data and annual El Niño Southern Oscillation (ENSO) and summer SST such that cooler conditions are associated with older water. Thus, 14C is generally relatively stable with weak, potentially inconsistent associations to climate variables, but capable of infrequent excursions as illustrated by the unusually cold, old-water 1802–1812 interval.

After a summary assessment of certain selected early man sites in various parts of America, the environment of the Venezuelan coastal plain is discussed in order to evaluate the stratigraphy and radiometric dating of the Taima-Taima site, near Coro, Venezuela, where mammals, many now extinct, were killed by people making El Jobo points about 13,000 years ago.

Potentially important areas in Peru, Chile and Brazil are mentioned. Certain problems in the models and interpretation of South American paleoclimates are pointed out.

The presence of at least four different bifacially flaked stone projectile point traditions in widely separated and environmentally diverse parts of America between 11,000 and 13,000 yr ago suggests that the immediate cultural antecedents of these traditions were essentially independent of one another. From this it is argued that several early American flaked-stone point traditions developed indigenously in America from technological bases which were present in the Old World Middle Paleolithic.

The description of major South American Pleistocene sites by Lynch (1990) contains significant errors and omissions. The artifact assemblage at the Colombian site of Tibitó, dated at 11,740 ± 140 B.P., is much larger than indicated by Lynch and well represents the Abriense industry, which features small unifacially retouched flake tools and core tools, with no stone projectile points. Lynch did not describe the 1976 stratigraphic profile at the Venezuelan site of Taima-Taima, and he failed to refer to the evidence for butchering of the juvenile mastodon with which an El Jobo projectile point fragment and a utilized flake were associated directly. The descriptions of Brazilian sites also feature serious mistakes. For the site of Alice Boër, Lynch overlooked a thick sterile stratigraphic unit (Bed IV) that intervenes between Bed III, with its thermoluminescence dates as early as 10,970 ± 1020 B.P. and radiocarbon dates as early as 14,200 ± 1150 B.P., and the artifact-bearing surface of Bed V. For Lapa Vermelha, Lynch failed to indicate that several artifacts were recovered from an older cemented cave fill that yielded radiocarbon dates of 22,410 B.P. and > 25,000 B.P. Lynch’s description of the site of Toca do Boqueirào da Pedra Furada does not correspond to eyewitness reports, and his description of the nearby Toca do Sitio do Meio was incomplete and confused. Finally, in his description of the stratigraphy of the Patagonian site of Los Toldos, Cueva 3 Lynch misquoted and misconstrued the original reports, which indicate clearly the stratigraphic priority and integrity of the Level 11 industry. For accurate descriptions of early South American archaeological sites, readers are urged to examine the original sources.