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1 summary From San Francisco Bay to the Santa Barbara Channel, the California coast is well known for its large prehistoric shell middens and mounds created by sedentary hunter-gatherer populations who harvested rich marine, estuarine, and terrestrial habitats. Except for the very large shell mounds that once lined San Francisco Bay, most of California’s largest shell middens are considered distinct from megamiddens that have been identified in many parts of the New and Old Worlds. Here, we examine large shell middens of the Santa Barbara Channel region, including the Northern Channel Islands, focusing on factors that contributed to the creation of massive accumulations of shell refuse at some sites. Population size, sedentism, freshwater availability, and a long occupational history are key variables contributing to the formation of large shell mounds, but the long-term productivity and resilience of intertidal habitats, the dietary importance of shellfish, and other factors are also important. introduction First coined in the late 1970s, the term megamiddens usually refers to large coastal shell mounds created by complex or sedentary coastal hunter-gatherers around the world. The most recognizable of these may be from the megamidden period defined for the west coast of South Africa, dating between about 3,000 and 2,000 years ago (Jerardino 1998; Mitchell 2002, 10). In the New World, another widely recognized series of large shell mounds has been identified in coastal Brazil (see Gaspar et al.; Klokler; and Okumura and Eggers, chaps. 7, 11, and 8 in this volume), with the largest of these Brazilian sites estimated to contain some 2.5 billion shellfish, and dated to after about 5,000 years ago when eustatic sea-level rise began to slow and shorelines stabilized. Along the southwest coast of Mexico, Barbara Voorhies and Douglas J. Kennett have investigated a series of large mounded shell deposits up to 7.0 meters deep, with dense midden deposits dominated by marsh clam shell and dated between about 5,000 and 3,500 years ago (Kennett, Voorhies, and Martorana 2006; Voorhies and Gasco 2004). Kennett and colleagues (2006) argued that these sites are key to understanding the transition from hunter-gatherer populations to maize-based agriculturalists in the region. In the United States, large shell mounds dating between about 7,200 and 2,400 years old have been identified in southeastern and midwestern sites (Sassaman 2004, 255– 58). This time period is often called the Shell Mound Archaic and usually refers to interior, freshwater shell mounds, although large coastal shell rings and mounds have also been identified along the Gulf and Atlantic coasts (e.g., Thompson and Pluckhahn 2010). In some cases these shell mounds may have been created as midden deposits and tied to the stabilization of sea levels and river morphology and the increased productivity of shellfishing during summer months (Steponaitis 1986). However, a growing number of researchers argue that many of these large shell mounds and coastal shell rings were intentionally constructed as part of ceremonial and burial landscapes that evolved in complexity through time (e.g., Claassen 1996; Russo 1994). From its foundation in the Middle Archaic, shell mounding traditions in the American Southeast extended into the Historic period. At European contact, the Calusa of southwestern Florida constructed massive shell mounds, which served as living and CHAPTER ONE Factors Influencing the Formation of Large Shell Mounds in California’s Santa Barbara Channel Region Todd J. Braje, Jon M. Erlandson, and Torben C. Rick 2 Todd J. Braje, Jon M. Erlandson, and Torben C. Rick ceremonials platforms (Widmer 1988), and represent the fruition of thousands of years of coastal hunting and gathering , sociopolitical evolution, sea-level rise, and the construction of anthropogenic landscapes. In California, the most widely recognized large shell mounds come from the San Francisco Bay area. In the early 20th century, Nels C. Nelson (1909) recorded 425 shell middens along San Francisco Bay; some of these were very large shell mounds, the earliest of which are now known to date to about 4,000 years ago (Broughton 1994a, b, 376; Lightfoot and Luby 2006). The Emeryville shell mound, for instance, was 300 meters long, 100 meters wide, and nearly ten meters deep (Broughton 1994a, b; Schenck 1926). San Francisco Bay shell mounds vary tremendously in size and shape and have been regarded, primarily, as refuse debris, or kitchen middens. Many of the mounds contained human burials, however—thousands of them in some instances—and certainly served a ceremonial function...

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