Examining the ecology and archaeology of black turban snails (Chlorostoma [Tegula] funebralis), found along North America's Pacific Coast from British Columbia to Baja California, we present evidence for 12,000 years of human predation in Northern Channel Island shell middens. Often viewed as evidence for Late Holocene economic intensification along the southern California Coast, we identified black turban middens dated to the terminal Pleistocene, as well as the early, middle, and late Holocene. Despite their small size and lower ranking as a prey species, humans harvested black turban snails because of their abundance, aggregation, and accessibility during daily tidal cycles. Examining 19 discrete archaeological components (with a total MNI of similar to 7,800) from San Miguel and Santa Rosa islands, we used a Shell Weight/MNI Index to document fluctuations in the mean size of black turban shells through time, identifying patterns attributed to a combination of environmental and demographic changes, including variation in the intensity of human predation.

Using several methods to distinguish dart and arrow points, archaeologists have suggested that the bow and arrow appeared in various parts of the world between similar to 65,000 and 1,000 years ago. Hildebrandt and King (2012) proposed a dart-arrow index (DAI) to help differentiate dart and arrow points, rejecting claims that the bow and arrow was introduced to western North America prior to the Late Holocene. We used the DAI and other methods to evaluate similar to 11,700-year-old projectile points from Santa Rosa Island, obtaining mean values below the threshold for darts, comparable to several North American arrow point types. We have no direct evidence that these small points were used on darts, arrows, or hand-thrown spears, but faunal associations suggest that they may have served as harpoon tips used on atlatl darts to capture birds, fish, and marine mammals. The DAI and other methods for discriminating between dart and arrow points are based almost exclusively on ethnographic and archaeological specimens from interior regions. Our analysis suggests that such methods should not be applied universally, especially in coastal or other aquatic settings, and that archaeologists should continue to critically assess the antiquity of the bow and arrow and the function of projectile points worldwide.

We estimate seasonality of shellfish harvest and site occupation for four Early Holocene shell middens on California's San Miguel Island using a robust dataset of 449 delta O-18 measurements from 84 mussel shells (Mytilus californianus). Seasonality was assigned to prehistoric mussels using palaeo sea-surface temperature (PSST) estimates from isotopic data obtained across full shell profiles.The results suggest that PSSTs around San Miguel Island were generally cooler between similar to 10,000-8600 calBP and that mussels were harvested in a range of water temperatures which suggest a mix of seasonal and year round harvesting at the four sites.Two substantial shell middens dated to similar to 10,000 and similar to 9000 calBP appear to have been residential basecamps where Paleocoastal peoples harvested shellfish during all four seasons. These data suggest that Early Holocene peoples occupied the Channel Islands year round and highlight the importance of stable isotope analysis of marine shells for helping evaluate human settlement and subsistence strategies along the Pacific Coast.

Analyzing stable isotopes in mollusk shells allows archaeologists to address issues ranging from seasonality of harvest, to settlement and subsistence strategies, sea surface temperatures, and nearshore paleoecology. Studying California mussel shells from an approximate to 8,800-year-old shell midden on San Miguel Island, we investigate how mollusk growth rates influence sampling strategies for determining seasonality. Using a fully profiled shell as a standard to interpret more limited measurements (terminal growth band plus one) on 39 additional shells, we identified what appeared to be a multi-seasonal occupation. Sampling 20 of the 39 shells more intensively, however, changed our conclusions about season of harvest for 35 percent of the analyzed shells, producing data more consistent with other evidence for a short-term occupation of CA-SMI-693. Sampling strategies for determining seasonality from marine mollusks should carefully consider the ecology of individual species, particularly for fast-growing shellfish such as California mussels. [Supplementary material is available for this article. Go to the publisher's online edition of Journal of Island & Coastal Archaeology for the following free supplemental resource(s): Appendix 1. Reported C-13 and O-18 and inferred temperature values for all isotopic determinations from forty analyzed California mussel shells from CA-SMI-693.]

Three archaeological sites on California’s Channel Islands show that Paleoindians relied heavily on marine resources. The Paleocoastal sites, dated between ~12,200 and 11,200 years ago, contain numerous stemmed projectile points and crescents associated with a variety of marine and aquatic faunal remains. At site CA-SRI-512 on Santa Rosa Island, Paleocoastal peoples used such tools to capture geese, cormorants, and other birds, along with marine mammals and finfish. At Cardwell Bluffs on San Miguel Island, Paleocoastal peoples collected local chert cobbles, worked them into bifaces and projectile points, and discarded thousands of marine shells. With bifacial technologies similar to those seen in Western Pluvial Lakes Tradition assemblages of western North America, the sites provide evidence for seafaring and island colonization by Paleoindians with a diversified maritime economy.

During the Pleistocene, California’s Northern Channel Islands were parts of the paleo-island of Santarosae, colonized by maritime peoples at least 13,000 years ago. Since the last glacial maximum, rising seas have flooded over 700 km2 of former coastlines and coastal lowlands of Santarosae where additional and earlier evidence for human occupation may exist. Recent research has shown that an archaeological search of these drowned landscapes may provide broader insights into the nature of Santarosae’s earliest human settlement, unobtainable through terrestrial archaeology. Using GIS, elements of the terrestrial landscape (topography, geology, caves, and springs) of Santarosae were overlain with reconstructed shorelines and the location and characteristics of known terrestrial archaeological sites to predict where sites may exist in the submerged maritime landscape. The key goals of the project were to evaluate the efficacy of predictive models in the search for early coastal sites, to determine whether the location and environmental variables of sites above the sea hold predictive value for finding submerged sites offshore, and to search for submerged cultural evidence in the high priority areas of the submerged landscape determined by the models.

To investigate potential human impacts on California Channel Island shellfish stocks over the past 10,000 years, we measured 1718 owl limpet shells from 19 archaeological components on San Miguel Island. Inhabiting the middle intertidal zone of Pacific Coast rocky shores, owl limpets are slow-growing mollusks that can live for 30 years and reach lengths of over 100 mm. Recent ecological studies indicate that owl limpets are highly susceptible to heavy human predation, which results in reduced mean shell sizes among Lottia populations along the coasts of Alta and Baja California. On San Miguel Island, we identified a significant trans-Holocene reduction in mean owl limpet size, beginning more than 6500 years ago and accelerating at least 4400 years ago. Fluctuations in limpet size show no clear correlation with changes in sea surface temperature and marine productivity, suggesting that increased predation by growing human populations was primarily responsible for the reduction in Lottia size over time. Our results provide further evidence that prehistoric peoples significantly influenced nearshore fisheries long before the development of the commercial and industrialized fisheries of historic times. (C) 2010 Elsevier Ltd. All rights reserved.