The Oregon Coast Archaeological Survey:

Radiocarbon Dating and Geoarchaeology Program

Jon M. Erlandson, Robert J. Losey, and Madonna L. Moss

Department of Anthropology, University of Oregon, Eugene, OR 97403-1218


For much of the past 10 years, with colleagues at the University of Oregon (UO), we have been involved in an intensive effort to study and protect the archaeology and history of the Oregon Coast. Our work, encouraged by the natural beauty of the Oregon Coast, has been driven by a sense of urgency because the archaeology and history of the area is rapidly being lost to erosion, development, and looting. The knowledge that much less is known about the archaeology of the Oregon Coast than adjacent areas adds to that urgency. With the support of federal and state agencies, several Oregon Coast Native American tribes, and literally scores of volunteers, we have made tremendous progress in understanding Oregon Coast archaeology and the destructive processes that threaten it. There is much left to be done, but we summarize some of the highlights of our recent work here, focusing on efforts to radiocarbon date Oregon Coast sites, develop more accurate chronologies for Oregon Coast archaeology, and examine the geological processes that have affected the peoples and archaeological record of the region. Here, we also provide a link to the Oregon Coast Archaeological Survey’s (ORCAS) Radiocarbon Data Base.

The University of Oregon and the Oregon Coast: A Brief History

Archaeological studies of the Oregon Coast began in the 1870s, as members of the U.S. Coast and Geodetic Survey mapped the area and explored its natural and cultural history. Early work by UO researchers included Leatherman and Krieger’s work on the lower Coquille River in the 1930s. Intensive coastal research began in 1950, when Luther Cressman initiated an Oregon Coast Prehistory Program at the UO. Cressman’s interest in the coast stemmed from his work in the Great Basin and his curiosity about the relationships between interior and coastal peoples in Oregon and the Pacific Northwest. Cressman hired Lloyd Collins, who spent 120 days surveying the coast from the Columbia River mouth to Cape Blanco, complementing a survey of the southern Oregon Coast done in the 1930s by Joel V. Berreman. Collins and Cressman recorded 133 sites, which brought the total number of documented Oregon Coast sites to about 178.

Between 1952 and 1958, Cressman directed excavations at two Oregon Coast village sites: 35-CS-5 near Bandon and 35-TI-1 near Netarts. Four seasons of fieldwork at the latter site were reported in Thomas Newman’s dissertation in 1959, the first PhD degree granted by the UO’s Department of Anthropology. Cressman and Newman’s work at 35-TI-1 also produced the first radiocarbon (14C) dates from an Oregon Coast archaeological site. In 1963, however, Cressman settled into an active retirement, focusing mostly on work that took him away from the Oregon Coast. By the 1970s, the Oregon Coast Prehistory Program had faded to a memory and the focus on Oregon Coast archaeology shifted to Oregon State University, where former UO students Richard Ross and Roberta Hall were teaching and developing interests in coastal archaeology.

In the 1980s, UO work on the Oregon Coast was revived by the Ph.D. research of Rick Minor (1983) around the Columbia River mouth and Thomas Connolly (1986) in the Klamath Mountains area. Momentum grew in 1988, with Connolly’s multidisciplinary research in the Seaside area of the north coast. In 1990, Rick Minor and Ruth Greenspan revived the Coastal Prehistory Program and began a series of excavations sponsored by the Museum of Natural History. In 1990, Moss and Erlandson joined the UO Anthropology faculty, bringing extensive experience in Pacific Coast archaeology and an enthusiasm for the study of maritime peoples in general. This fortuitous coalescence of individuals with common interests led to dramatic growth and development in an interdisciplinary UO program that has come to be known as the Oregon Coast Archaeological Survey (ORCAS).

Oregon Coast Archaeology: A Chronological Perspective

In 1991, Lee Lyman of the University of Missouri published the book, Prehistory of the Oregon Coast, summarizing the status of Oregon Coast archaeology and stimulating further research on a variety of issues. As a benchmark for measuring our progress in the 1990s, Lyman listed approximately 50 Oregon Coast sites that had been excavated in the last 120 years and 123 14C dates from 25 coastal sites. Lyman also suggested that the Native peoples of western Oregon did not intensively use the resources of the sea until after about 3500 years ago. This conclusion, based on the dearth of older 14C dated Oregon Coast sites, was at odds with the antiquity of maritime adaptations in regions to the north and south, especially the southern and central California coasts and the British Columbia and southern Alaska coastal regions. It is similar, however, to patterns found along the coasts of northern California and Washington, in areas that fall within what geologists call the Cascadia Subduction Zone (figure 3).

In evaluating Lyman’s hypothesis that maritime cultures did not develop along the Oregon Coast until the Late Holocene, UO scholars felt there were too few 14C dated sites to support such conclusions and suspected that geological forces may play an unusually powerful role in shaping the archaeological record of the area. To examine these issues, ORCAS archaeologists set out to increase the number of 14C dated sites for the Oregon Coast, to systematically excavate samples from a larger number and broader range of coastal sites, and to more closely examine the geological processes that might bias the archaeological record.

In the last 10 years or so, the first component of this research campaign has obtained more than 350 14C dates from over 160 Oregon Coast sites. With support from an Oregon Sea Grant award associated with PSU’s Paleodunal Landscapes Project, we also completed a data base including all known 14C dates from Oregon Coast archaeological sites. Ten years after Lyman’s summary, we now have 539 14C dates from 194 coastal sites in our ORCAS Radiocarbon Data Base. This is an increase of almost 450 percent in the total number of 14C dates and an increase of 775 percent in the number of dated sites.

Our data base includes 14C dates obtained by different investigators over the past four decades, dates run by different laboratories using different techniques, and dates based on the analysis of different types of organic materials (marine shell, charcoal, wood, bone, etc.). For a variety of reasons, 14C dates often differ from calendar ages and different organic materials used by humans at the same time can produce ages that vary by centuries. To compensate for some of these problems, 14C dates have to be calibrated to calendar ages for effective comparison and maximum chronological resolution. As part of the Sea Grant Paleodunal Landscapes project, we have calibrated nearly all of the 14C dates in our data base using the CALIB 4.3 program designed by Minze Stuiver and Paula Reimer of the University of Washington’s Quaternary Isotopes Laboratory. These calibrated dates are presented in Figure 1,which plots all dates from Oregon Coast archaeological sites by 250 year time intervals over the past 9250 years.

The distribution of dates shows that a number of Oregon Coast archaeological sites have produced 14C dates greater than 3500 years, suggesting that Native peoples did occupy the Oregon Coast during the Middle and Early Holocene. Some of the earliest of these dates, in fact, come from a small shell midden site located on the southern Oregon Coast dated between about 8400 and 8500 years ago, where thousands of burned mussel shells show clear evidence for the use of marine resources. The chronological distribution of 14C dates also shows, however, a dramatic increase in the number of dates during the Late Holocene, particularly after about AD 500. Figure 2, which plots the number of 14C dated Late Holocene coastal sites per 100 year interval illustrates this exponential growth even more effectively. During the 400 years between AD 200 and 600, for instance, there is an average of just 5.5 14C dated sites per century on the entire Oregon Coast. In the next 400 years (AD 600-1000), the average number of dated sites doubles to 11, then more than doubles again between AD 1000 and 1400, with an average of 23 dated sites per century. The century from AD 1600 and 1700 sees yet another doubling to 46 dated Oregon Coast sites before a precipitous drop in the following century.

The overall distribution of 14C dates from Oregon Coast sites supports both an early human occupation of the region and a dramatic increase in coastal sites during the Late Holocene. A sharp increase in the number of Late Holocene sites is typical of the entire Pacific Coast of North America, but the very limited number of Early and Middle Holocene sites in Oregon and the broader Southern Northwest Coast region is atypical. Was Lyman correct in proposing that intensive occupation and use of the Oregon Coast did not develop until the Late Holocene? We strongly suspect that geological forces have played an unusually significant role in structuring the archaeological record of the Oregon Coast, so that the spatial and temporal distribution of surviving sites does not accurately represent the full range of sites left by early peoples.

Geological Processes Affecting the Oregon Coast Archaeological Record

So far, exploration of geological influences on Oregon Coast archaeological sites has focused primarily on coastal erosion and an emerging record of large episodic earthquakes associated with the Cascadia Subduction Zone (Figure 3). The west-facing Oregon Coast is exposed to the full brunt of swells generated by North Pacific trade winds and storms, and is characterized by the highest average wave energies along Pacific Coast. These high waves cause relatively intensive coastal erosion that is currently damaging or destroying scores of Oregon Coast archaeological sites. When this wave energy is combined with a history of large subduction earthquakes, which have caused rapid subsidence of many Oregon Coast landforms, it seems likely that significant numbers of coastal archaeological sites have been destroyed over the millennia. Such destruction should affect older sites more heavily than recent sites, since the older a site is the more earthquake-erosion cycles it will have been exposed to, not to mention impacts related to postglacial sea level rise and other geological processes.

In a recent paper, Erlandson, Tveskov, Moss, and Wasson (2000) also explored erosional changes in Oregon Coast river mouths as a mechanism for the destruction of archaeological sites. They documented the rapid and dynamic migration of one river mouth along the southern Oregon Coast as it cut through a large dune field and destroyed numerous archaeological sites during a period of relative tectonic stability. Since Oregon Coast river mouths were generally the location of intensive Native American settlement, and such migrations are well documented for other river mouths in the area, Erlandson et al. (2000:14) proposed that such shifts may help account for the lack of early sites along the Oregon Coast and linked such changes to the formation of extensive dune sheets:

Such processes are not unique to Oregon or the southern Northwest Coast, but they seem to be more pronounced in the area. This may be due, in part, to the extent of recent dunes along the shorelines of Oregon and Washington, where approximately 45% and 31% of the coast is lined with sand dunes . . . . Such coastal dunes - unconsolidated, unstable, and prone to rapid erosion - tend to block or deflect many rivers and streams of the southern Northwest Coast, adding an element of coastal dynamism that is much less common in adjacent areas of the Pacific Coast.

Currently, working with geologists from Portland State University and Oregon State University, Erlandson, Losey, and Minor are evaluating the effects of Holocene dune building on the archaeological record of the Oregon Coast. As alluded to above, relatively recent sand dunes are present along almost one-half of the Oregon Coast, including the massive dune field extending for over 50 miles (80 km) from the mouth of the Siuslaw River near Florence to the entrance of Coos Bay. The chronology of dune building along the Oregon Coast is still being worked out, but many of the Holocene dunes appear to have begun forming between about 7000 and 3000 years ago. Where such dune formations are deep or extensive, they often dramatically altered the Oregon Coast landscape. In many cases, they must have buried older coastal archaeological sites or created lakes that flooded such sites. Although we are still analyzing this issue, the formation of Holocene dune fields seems likely to be a significant contributor to the dearth of Oregon Coast archaeological sites 14C dated to the Middle and Early Holocene.

As Erlandson et al. (2000:14) noted:

To fully understand the geological forces shaping the archaeology of the southern Northwest Coast, researchers must consider not just the tectonic history of the area, but its riverine dynamics, the unprotected and wave-battered nature of much of the coast, the extent of Holocene dune fields, and the earthquake, tsunami, and erosion history of the area. All these forces, working independently at times and together at others, exert a powerful influence on the preservation of archaeological sites. Before we can attribute the dearth of early sites along the southern Northwest Coast to a relatively late development of maritime societies, we must understand the effects of geological processes on the preservation of coastal archaeological sites. In recent years, the accumulating archaeological and geological data are building a compelling case that the archaeological record of coastal settlement is fundamentally shaped and biased by geological forces.

Currently, studies of the geological forces shaping the archaeological record of the Oregon Coast are just one aspect of ORCAS’ multidimensional analysis of the history of Oregon Coast tribes and environments taking place at the University of Oregon.

The Oregon Coast Archaeological Survey: Overview of Accomplishments

Since the 1990s, University of Oregon archaeologists have changed the archaeological landscape of the Oregon Coast from something of a black hole into an area vital for understanding a variety of issues in Pacific Coast archaeology and history. Our ORCAS colleagues - including Mel Aikens, Kitty Bernick, Scott Byram, Tom Connolly, Lori Erickson, Ruth Greenspan, Charlie Hodges, Jennifer Jones, Don Ivy, Robert Kentta, Chris Landreau, David Lewis, Pat McDowell, Rick Minor, Denise Mitchell, Guy Tasa, Mark Tveskov, Stead Upham, George Wasson, Don and Patty Whereat, Jason Younker, and many others - have included scores of faculty, staff, graduate and undergraduate students, tribal members, and other volunteers. To support a variety of projects, ORCAS participants have obtained grants, contracts, or other support from the National Science Foundation,University of Oregon, Oregon State Historic Preservation Office, National Park Service, Oregon Department of Transportation, Oregon Sea Grant, U.S. Forest Service, U.S. Fish and Wildlife Service, Coquille Indian Tribe, Confederated Tribes of the Coos, Lower Umpqua, and Siuslaw Indians, Confederated Tribes of Siletz Indians, Sigma Xi, the Smithsonian Institution, and the Association of Oregon Archaeologists.

A major component of ORCAS research has involved the salvage of archaeological data from threatened sites. Such investigations have included detailed research led by Minor and Greenspan at a number of sites in the Cannon Beach, Nehalem Bay, Cape Perpetua, Siuslaw Dunes, Winchester Bay, Hauser, Cape Blanco, and Boardman State Park areas. Similar projects have been conducted by Connolly and Tasa at sites in the Clatsop Plain, Seaside, and Central Coast areas, by Tveskov and Byram at several sites in the Coquille River and Coos Bay areas, by Erickson and Erlandson in the Heceta Head area, by Losey in the Netarts and Nehalem areas, and by Moss and Erlandson in the Pistol River area.

Another major component of ORCAS has involved a coast-wide survey, evaluation, and dating project directed by Moss and Erlandson for archaeological sites on State Lands of the Oregon Coast. During this project, over 100 sites were visited to evaluate their condition and 14C date most of them, and 89 sites located in coastal State Parks were nominated to the National Register of Historic Places. In 1997, all 89 nominated sites were officially placed on the National Register. During 1998-99, Erlandson, Byram, and Losey extended this effort by nominating 10 more sites located on State Park, State Tidelands, and National Forest lands to the National Register, including a number of important intertidal fishing structures.

A major emphasis of our SHPO-funded surveys was the first systematic search for intertidal sites in Oregon Coast estuaries. Previous research in Washington, British Columbia, and southeast Alaska had identified numerous wood-stake tidal fishing weirs, fence-like structures fish swam over during high tide then were trapped behind as the tide went out. Spearheaded by Byram, Tveskov, and Erlandson, we have now recorded and dated dozens of intertidal fishing weirs in Oregon Coast estuaries, including sites that range from about 75 to 3400 years old (see Figure 4). The highly unusual preservation of wood artifacts - mostly stakes, but including woven lattice panels in some sites - in these "wet" sites allows us to address questions not normally approachable in terrestrial sites. In studying the age, structure, and location of fishing weir sites, we have transformed the Oregon Coast from terra incognita to the area of the Northwest Coast where such sites are the most thoroughly documented.

In the last decade, ORCAS archaeologists have recorded more than 110 Oregon Coast archaeological sites, conducted test excavations at approximately 30 sites, obtained more than 350 14C dates for 165 coastal sites, and nominated more than 100 sites to the National Register of Historic Places. Among other things, we have discovered an 8500 year old site on the south coast, the oldest yet documented in the area. We have dated a Spanish rigging block found on a north coast beach to AD 1635 and linked it to the famous Nehalem "Beeswax" Ship, probably a Manila galleon that wrecked on the Oregon Coast. In a Washington D.C. archive, Scott Byram discovered the oldest known map depicting Lewis and Clark’s winter camp at Fort Clatsop, just one of over 100,000 pages of historical and anthropological documents returned to Oregon from east coast archives. ORCAS participants have published more than 25 articles about Oregon Coast archaeology and history, with six PhD and eight Masters degrees either completed or in progress. In the process, we have raised the profile of Oregon Coast archaeology and the University of Oregon’s research efforts.

Although only a brief synopsis of ORCAS-related research efforts during the last decade has been provided here, it should be clear that this has been an extremely productive period for Oregon Coast archaeological, anthropological, and historical research. We hope the next 10 years will be equally productive.


We are indebted to the Oregon Sea Grant program and to Curt Peterson at Portland State University for their support of our efforts in the compilation and calibration of the ORCAS Radiocarbon Data Base and our study of the effects of Holocene dune building on the Oregon Coast archaeological record. We also thank the Oregon Department of Parks and Recreation, the University of Oregon, the Oregon Department of Transportation for extensive support of ORCAS-related activities over the years, including radiocarbon dating. Some of the research on dune sites of the northern Oregon Coast has been funded by NSF, AOA, and Sigma Xi grants awarded to R. Losey and M. Moss. Finally, our sincere thanks to the many colleagues who have contributed 14C dates to the ORCAS data base and to the Native American tribes and tribal members who have supported and collaborated in many aspects of our work. Portions of this essay have been adapted from an article by Erlandson and Moss published in the Archaeology at the University of Oregon Newsletter (2000), "Ten Years After: The Oregon Coast Archaeological Survey."

Related Readings*

Byram, R. Scott 1998 Fishing Weirs in Oregon Coast Estuaries. In Hidden Dimensions: The Cultural Significance of Wetland Archaeology, edited by K. Bernick, pp. 199-219. Vancouver: University of British Columbia Press.

Erlandson, Jon M. and Madonna L. Moss 1999 The Systematic Use of Radiocarbon Dating in Archaeological Surveys in Coastal and Other Erosional Environments. American Antiquity 64:431-443.

Erlandson, J. M., M. A. Tveskov, and R. S. Byram 1998 The Development of Maritime Adaptations on the Southern Northwest Coast of North America. Arctic Anthropology 35(1):6-22.

Komar, P. D. 1998 The Pacific Northwest Coast: Living with the Shores of Oregon and Washington. Duke University Press.

Losey, Robert J. (editor) 2000 Changing Landscapes: Proceedings of the 3rd Annual Coquile Cultural Preservatioin Conference, 1999. North Bend: Coquille Indian Tribe.

Lyman, R. Lee 1991 Prehistory of the Oregon Coast. New York: Academic Press.

Minor, Rick, and Wendy C. Grant 1996 Earthquake-Induced Subsidence and Burial of Late Holocene Archaeological Sites, Northern Oregon Coast. American Antiquity 61:772-781.

Moss, Madonna L. and Jon M. Erlandson 1995 Reflections on North American Pacific Coast Prehistory. Journal of World Prehistory 9:1-45.

Moss, Madonna L. and Jon M. Erlandson 1998 A Comparative Chronology of Northwest Coast Fishing Features. In Hidden Dimensions: The Cultural Significance of Wetland Archaeology, edited by K. Bernick, pp. 180-198. Vancouver: University of British Columbia Press.

Younker, Jason, Mark A. Tveskov, and David G. Lewis 2001 Changing Landscapes: "Telling Our Stories.":Proceedings of the 4th Annual Coquille Cultural Preservation Conference, 2000. North Bend: Coquille Indian Tribe.

*Specific references to site names or locations have been omitted from this article to protect archaeological sites from vandals or looters.