Humans have inhabited coastal areas and made use of their resources for hundreds of thousands of years. The richness of the coastal zone, the overlapping of maritime, littoral and inland resources, and the ease of transportation along it have led people to cluster along shores, including the people of today who are destroying much of the record of past inhabitants. However, coastlines are also the most dynamic environments on earth. Tides and currents effect daily and seasonal changes in the shore margin; storms dramatically resculpt the shore; isostatic, eustatic, and tectonic changes (cf. Isostacy, Eustacy, Tectonics, and Neotectonics) can result in former coastlines being located far inland or far out to sea.
In trying to understand the human use of coastlines, it is necessary first to discover where the coast was at the time the site one is interested in was occupied. Due to the ever-changing relationship between the land and the sea, sites of past coastal people may be well inland, well submerged under the sea or still coastal. To discover past coastal sites, it is essential that archaeologists work in cooperation with geologists and other coastal scientists, and take into account both local and global factors which influence relative sea level (cf. Archaeological Site Location). Once sites are located and are determined to be cultural rather than natural features, archaeologists turn to more culturally interesting questions about human adaptation to the coastline and how it changed with time. For example, were these people simply living by the sea, like summer beach residents today or in Pompeii, or were they using marine resources? If they were using marine resources, was their primary focus on industrial or alimentary needs? If the latter, were they littoral hunter-gatherers, who made use of coastal and nearshore resources, or were they maritime hunter-gatherers, who had boats from which to gather creatures of the deep sea?
To understand human adaptation to coastal environments, archaeologists in all parts of the world have looked particularly closely at diet, at the season of occupation of sites, and at relationships between coastal and inland peoples. Changes in adaptation can be forced by changes in the environment, by cultural change and development or, most likely, by a complex interaction between culture and environment. In the short term, archaeologists consider the human response to disaster: for example, if their settlement is destroyed by a tsunami (q.v.), do people move away or do they reestablish themselves in the same place? One can examine changes through time in coastal occupation, both those forced in some way by environmental changes, for example, rising or falling sea levels, changes in ocean temperatures, which affect littoral or maritime resources, and those caused by social, political, or demographic changes in the human populations of the coast. In the following pages, studies from various parts of the world will be used as exemplars of current examinations of these issues.
The vast majority of coastal archaeological sites are shell middens, piles of shells left behind by people eating mollusks and/or using their shells for industrial or ceremonial purposes. Other sites consist of modifications of the shoreline to enhance the productivity of the sea or humans’ ability to harvest its resources.
The archaeology of coastlines has a long history, with some of the earliest studies in archaeology focusing on the Danish kjokken-möddings, or shell middens, of the Mesolithic period. These were recognized as cultural by 1837, and shortly thereafter, the Royal Danish Academy of Sciences established a commission to study them, directed by Jens J.A. Worsaae, who was the world’s first professional prehistoric archaeologist. In the 1850s, Worsaae and his colleagues published six volumes on their studies, which established that the Danish middens were cultural and had developed through time, that the only domesticated animal the people possessed was the dog, and that these middens were occupied in all seasons of the year but summer. They also identified the plants of the paleoenvironment and studied the distribution of cultural features within the mounds. Finally, they initiated experimental archaeological studies: they gave bones to dogs to chew on to determine why there was a preponderance of bird long-bone mid-shafts in the middens. This work was highly influential, stimulating scientists to study local shell middens on both coasts of the United States, and in Japan, Brazil, and Southeast Asia. By 1911, shell middens had been examined from the Aleutian Islands to South Africa (Trigger 1989). The study of coastal sites has not slowed down, since: a 1991 bibliography of coastal and maritime archaeology, admittedly incomplete, contains 2800 entries (Kerber 1991).
Quaternary International vol. 239, issues 1-2: 2, 2011
Balbo et al
Rabett et al.
Alvarez et al.
State of the Art
Wagner et al.
Colonese et al.
Habu et al.
Ramos et al.
Briz et al.
Tierra del Fuego
Szabó and Amesbury
Tropical island Asia-Pacific
Erlandson et al.
Saunders and Russo
Orquera et al.
SW Patagonia and Tierra del Fuego
Gutiérrez-Zugasti et al.
Channel Islands California
Demarchi et al.
Red Sea and Scotland
Rabett et al. provide an overview of shell midden research but then turn to freshwater middens. Alvarez et al. review shell midden research overall without any geographic focus, while six of the contributions focus on area reviews (Wagner et al., Colonese et al., Habu et al., Ramos et al., Briz et al., Gutiérrez-Zugasti et al.). The remaining articles, which primarily present new research (Szabó and Amesbury, Erlandson et al., Saunders and Russo, Orquera et al., Rick) or new methods of analysis (Demarchi et al.), will be discussed further below.
Following up on these studies, in an ethnoarchaeological and archaeological study of shell middens in Senegal, Hardy and colleagues (2016) extensively reviewed reports on mid-Holocene shell middens and mounds around the world. Their references, added to the ones above, will be invaluable for anyone interested in shell midden research.
Finding Coastal Sites
Finding coastal archaeological sites can be very difficult due to isostatic, eustatic, and tectonic forces that change the location of the sea relative to the land. The west coast of North America is an area in which all of these forces have been active to varying degrees during the period of human occupation. Fedje and Christensen show that, in the Queen Charlotte Islands, coastlines dating from 13,000 to 9500 bp [uncorrected radiocarbon dates] are deeply drowned while those dating from 9200 to 3000 bp are stranded in the rainforest up to 15 m above modern levels. “Coastlines have been approximately coincident with the current position for only the last two to three millennia and for a century or two centered around 9400 bp” (1999, p. 635). Modeling these paleocoastlines (q.v.) allowed them to discover a number of coastal archaeological sites in both drowned and uplifted zones. Since then, 20 additional raised beach sites have been found, and the search for drowned shorelines with sites has continued (Fedje et al. 2005). From southern Washington to northern California, on the other hand, late prehistoric coastal sites have been drowned due to earthquake-induced subsidence (cf. Subsiding Coasts) along the Cascadia subduction zone, seriously biasing our understanding of Washington’s prehistory (Cole et al. 1996). While many sites thus drowned may be lost, the authors have found a number of examples buried under tidal mud along coastal estuaries (q.v.). In southern California, Waters et al. (1999) have identified a complex series of terraces along streams that are caused both by global patterns of sea-level fall and rise and by local climatic factors, possibly in response to an El Niño-Southern Oscillation (q.v.) event. These events have caused pre-4000-year-old sites to be deeply buried and consequently difficult to find. The later sites, which are closer to the surface, have an advantage over many southern California sites in being below the bioturbation layer. Waters and his colleagues have found large late marine-oriented sites in these channels, which are changing our understanding of late prehistoric cultural development in this area.
Determining Site Function
Both Hardy et al. (2016) and Marquardt (2010) caution against the facile interpretation of the functions of shell mounds. Through their ethnographic research, Hardy et al. point out that “In the Saloum Delta, perceptions of the middens are not static and they change and evolve as the middens develop; they can be dumps, villages, cemeteries or burial sites, religious places, foraging locations and possibly even monuments; no interpretation excludes any of the others. We suggest that this fluidity in the meaning and use of middens, that we have detected challenges some of the fixed social interpretations that can be ascribed to middens and that rather that assigning specific meaning that suggests deliberate, pre-planned action sometimes over thousands of years, middens are more likely to have had many uses at different times during the course of their construction and active lives” (2016, p. 30). Similarly, Marquardt avers that only by using carefully sedimentological analysis can one determine the function of Southeastern US shell middens and mounds.
In many parts of the world, shell midden sites have been quarried out for fertilizer or to use as fill. Thus, many midden deposits may be lost or exist in places far removed from their original deposition. Even in remote places like the Shumagin Islands south of the Alaska Peninsula, people have moved midden from one island to another to serve as fertilizer for gardens. Thus, merely finding onshore shell deposits, even when it can be determined that they are of human creation, does not mean that one has found an archaeological site in situ.
In Sri Lanka, the lowering of sea level has led to shellfish dying and their shells being washed and blown into windrows on beaches, lagoon and lake bottoms, sand dunes, and headlands. These are often difficult to tell from cultural deposits although artifacts found among the shells suggest that people were responsible for some of the deposition (Katupotha 1995). In southwestern Louisiana, Henderson et al. (1998) also wished to determine whether shell-rich deposits on coastal beach ridges were natural or cultural. In this case, the archaeological deposits were found lying on or actually constructed out of reworked chenier (q.v.) deposits. The authors discovered a suite of taphonomic, sedimentologic, and stratigraphic methods, which served to distinguish the cultural deposits from the natural chenier deposits.
Butler and her colleagues have been working during the past decade to discover how natural deposits of salmon differ from those left by human hunter-gatherers. This is a particularly important problem in the Pacific Northwest where the harvesting and storage of vast quantities of anadromous salmon are thought to underlie the development of the cultural complexity for which the area is famous. Butler has looked at a particular site, the Dalles Roadcut on the Columbia River, and concluded that the deposition is probably cultural; has considered the varying natural decay of different salmon bones; and has investigated whether fish bones that have passed through mammalian digestive tracts bear recognizable marks (cf. Butler and Schroeder 1998). All of these studies aid archaeologists in determining whether salmon deposits are natural or cultural.
An ethnoarchaeological study of fish middens on the coast of Senegal showed that caught and filleted fish mimicked natural fish deposits as the heads were not removed in filleting and, therefore, the entire skeleton remained (Van Neer and Morales Muñiz 1992). On Lake Turkana in Kenya, on the other hand, investigators could distinguish base camps, fish processing camps, and fish waste discard sites from each other and from natural death assemblages by the nature and number of bones remaining (Stewart and Gifford-Gonzalez 1994). Both of these ethnoarchaeological studies can aid archaeologists in interpreting prehistoric shell deposits.
Related to the problem of distinguishing natural from cultural deposits is that of determining why species representation and shell size of shellfish found in middens might change through time. In looking at middens on the West Coast of Southern Africa, Jerardino (1997) determined that changes in species were due to humans exploiting different tidal zones, while size changes in individual species were due to a combination of water conditions and human exploitation.
Industrial and Ceremonial
The study of industrial and ceremonial uses of coastal resources, particularly shells, has increased tremendously over the past decade. In the 1990s, working in the Sinai, Bar-Yosef Mayer (1997) demonstrated that shells entered sites as raw materials for beads rather than as food remains, while in the Arctic, Savelle (1997) notes that whale bones are often more indicative of housing needs than diet. Most investigators look at shellfish gathering as an enterprise that requires few or no tools aside from a container in which to carry the collected goods. However, Johnson and Bonsall (1999) note that in both the Shumagin Islands in Alaska and in Scotland, tools are found in shell midden contexts which appear to have been used in the collection and processing of shellfish. Wedge-ended rods of stone or sea mammal bone are used for prying limpets from rocks and, possibly, for digging the animal out of its shell, while small splinters of bird bone are used to pry periwinkles and other small snails loose from their shells, developing worn points in the process. Jerardino (2016, p. 215) expands the recorded use of levers to South America, Africa, Australia, New Zealand, and the Pacific coast of North America.
Shell technologies have been studied from Upper Paleolithic Spain, where Patella shells were used both to process pigments and to tan hides (Cuenca-Solana et al. 2013), to Baja California, Mexico, where single-piece shell fishhooks dated to the terminal Pleistocene/early Holocene transition were found in levels which “contained a diverse assemblage of fish remains, including deepwater species, indicative of boat use” (Des Lauriers et al. 2017). In the Pacific, Pawlik et al. (2015), found a Tridacna shell adze in a site in the Philippines which showed that shell technology emerged in the early middle Holocene and implied an early human interaction between the Philippines and Melanesia. On the other end of the timescale, Kononenko et al. (2010) showed that turtle bone cleavers from Wuvulu Island, Papua New Guinea, which were traded to Germans in the nineteenth century were well-used and ready for discard rather than being manufactured for the tourist trade.
Marquardt and Kozuch (2010) published a fascinating article on the industrial and ceremonial uses of the lightning whelk (Busycon sinistrum) in the North American southeast and midsouth. In the same area, Wallis and Blessing (2015) looked at a large pit feature in Florida to understand feasting among small-scale hunter-gatherers. The remains included saltwater taxa which must have come from the Gulf or Atlantic coasts more than 100 km away. Also in Florida, Pluckham et al. (2016) identified stepped pyramids of shell from a terminal Late Woodland site. In Georgia, in addition to examining individual shells to determine the seasonality of use (see below), Thompson and Andrus (2011) also identified both gradual deposition of shells as food waste and short-term large-scale deposition of shells which might indicate that the rings became monuments. To the west, Gamble (2017) urged archaeologists to consider the ritual significance of shell mounds in southern California; while Whalen (2013) reinterpreted the huge caches of marine shell at Casas Grandes (or Paquime) in northwest Chihuahua, Mexico as “animate objects,” which formed “a vast repostitory of supernatural power that was a central part of the community’s ritual system.”
Four recent studies looked at shell beads: Tata et al. (2014) used experimental archaeology to analyze beads from Vale Boi, Portugal, and concluded that while species changed, technology remained the same over a long period of time; Chrisitiani et al. (2014) studied the site of Vela Apila (Corcula Island, Croatia) to understand Late Upper Paleolithic and Mesolithic personal adornments dating from 19.500–8150 cal BP. Diversity of shell species decreased to one type in the Mesolithic indicating that the site became an important procurement and processing center for Columbella rustica. On the Pacific Coast of North America, Coupland et al. (2016) found unequal distribution of shell and stone disc beads from 4000 cal BP leading them to conclude that material wealth-based inequality began earlier than previously thought on the Northwest Coast, while Smith et al. (2016) discovered that marine shell beads from the northern California, Oregon, and Washington coasts were deposited in a rockshelter in southcentral Oregon during the early Holocene.
Once coastal sites have been located and identified, archaeologists attempt to discover what people were doing at the sites. This involves figuring out what foods they were eating, by examining both the food remains left at sites and the bones of the humans, which reflect the nature of their diets. In looking at the food remains, it is necessary to figure out what the dietary implications are of, for example, ten bivalve shells versus two salmon bones versus one sea lion femur. Archaeologists are also interested in discovering whether people were using the site year-round or only seasonally, whether they were littoral gatherers or maritime hunters and fishermen, and what their relationship with other groups might be. Finally, archaeologists look both at individual sites occupied for a long period of time and at the pattern of sites within an area to discover how human adaptation to the coastline changed through time. Another line of discovery is provided by ethnoarchaeological and experimental studies (Briz Godino et al. 2011)
The most direct means of discovering what people ate is to examine their bones. Analyses of trace elements and stable isotopes can distinguish between diets rich in marine foods and those rich in terrestrial foods. Low Ba/Sr and Ba/Ca ratios and high δ13C values in bones indicate a diet rich in marine foods, while the reverse is true for terrestrial diets. High δ13C values also occur when plants such as maize, which use a C4 metabolic pathway, are eaten, but maize and marine foods in the diet can be distinguished by examining δ15N and δ34S values.
Gilbert et al. (1994) examined modern plants and animals of the western Cape of South Africa in order to determine marine and terrestrial signatures for Ba/Sr and Ba/Ca ratios, finding distinct differences in both edible tissue and bone. Reanalyzing bones, which had already been tested for δ13C values, led to the conclusion that both methods worked, but that stable isotopes revealed more subtle differences.
Aufderheide and his colleagues (1994) had the advantage of working with mummified human remains from northern Chile. Here, they were looking at recent immigrants to the coast from the highlands and discovered that the community appeared to have split into two different groups, one right on the coast subsisting almost entirely on marine foods, and the other in the mid-valley eating both marine foods, probably supplied by the coastal community, and valley bottom foods. These results were supported by the presence of external auditory canal extoses, formed due to prolonged cold water diving, in the coastal population.
In looking at the south Florida Calusa, Hutchinson et al. (2016) “combine data on the zooarchaeological and archaeobotanical remains from the archaeological sites with those from stable carbon and nitrogen isotopic ratios of archaeological human bone, and modern and archaeological plants and animals. These multiple lines of evidence confirm that marine-based protein and terrestrial C3 plants provided a large and reliable portion of the diet in southwestern Florida as early as 4000 years ago and up to European contact.”
Human remains are not always available in the sites or levels where archaeologists would like to find them, and the prehistoric people’s descendants are often not pleased to have their ancestors subjected to scientific analysis. Cannon et al. (1999) have demonstrated at the site of Namu on the British Columbia coast that dog bones can serve as surrogates for human bones in analyzing diets. It is probable that in most prehistoric coastal settlements the diet of dogs was very similar to that of their masters, thus providing archaeologists a much wider sample of bones to analyze for dietary information. Thornton et al. (2011) looked at the Angoon-Killsnoo area where seven of nine sites had herring bones, spanning 1800 years, pointed out that herring remains are found in Northwest Coast sites by 8–9.9 kya, and noted that this continued productively was possible due to managing people and marinescapes.
Another approach to dietary reconstruction is to estimate the amount of food represented by the remains present in a site. James Savelle has been particularly active in deriving meat utility indices for marine mammals (cf. Diab 1998). This also relates to issues of variable preservation, discussed above, and to recovery methods. Fish bones are often underrepresented in archaeological assemblages because of a lack of screening of excavated materials or of using screens with too large a mesh. Ross and Duffy (2000) have demonstrated that a 1 mm mesh screen results in considerably greater recovery of fish bones from an Australian site and have also developed deflocculation and flotation techniques, which make sorting the screened remains practical in the real world: sorting remains from a 100 ml dry screened sample took 20 h, whereas the deflocculated and floated sample was sorted in only 2.5 h. Moreover, the chemical added to water for flotation was sugar and an excellent deflocculant was baking soda, making the procedure inexpensive and safe as well. The result of the 1 mm screening was to verify the reports of southeast Queensland Aborigines that both fishing and shellfishing had been important to them since time immemorial in contrast to prior archaeological investigations in which the paucity of fish remains recovered had led to a hypothesis of a late introduction of fishing to this coast.
Analysis of midden materials also gives rise to problems concerning how to quantify the materials recovered. Faunal analysts now tend to provide both number of identified specimens (NISP) and a minimum number of individuals (MNI) data for mammal and fish remains, but the quantification of shellfish remains is a thornier issue. Shells appear in sites in the thousands and are often broken into small fragments. Because shells vary in size and in friability, NISP is not a useful figure. MNI is often used but ignores a great deal of the data since only the hinge areas of bivalves can be counted. Thus archaeologists have attempted to use the weight of shellfish remains as a proxy for the importance of various species in past diets. This is an area of active discussion (cf. Claassen 2000).
Season of Occupation
Coastal settlements can be year-round residences or can represent part of a seasonal round, being occupied for one or two periods during the year while the people live elsewhere, exploiting other resources, during the rest of the year. Determining seasonality from the middens themselves requires some means of discovering when animals were killed, which has proven possible for mammals, fish, and shellfish. Marine mammals are born at particular times during the year, so the age at death of immature animals can indicate when a site was occupied: if all of the young animals found in a site died at the same age, it suggests that the site was occupied for only that season. The analysis of seal bones in South Africa indicated that early in the Holocene people exploited seals periodically throughout the year, while in the late Holocene they restricted this activity to the spring (August–November; Woodborne et al. 1995). A similar pattern of change from year-round to seasonal occupation is seen in New Zealand through the analysis of seasonal and annual growth rings on Cod otoliths (earbones; Higham and Horn 2000).
A major approach developed over the past 15 years or so is sclerochronology, the study of physical and chemical accretionary structures of organisms such as shellfish and the seasonal and annual patterns in which they formed, coupled with the sequential analysis of oxygen isotopes (d18O) (see Andrus 2011 for an excellent review of the processes of analysis and the benefits and pitfalls for shell midden analysis). Recent studies have looked at the Northwest Coast of North America (Hallmann et al. 2013; Burchell 2013; Burchell et al. 2012), California (Culleton et al. 2009; Jew et al. 2013, 2014; Eerkens et al. 2013), Florida (Andrus and Thompson 2012; Wang et al. 2013), Mesolithic Europe (Dupont 2016), Libya (Prendergast et al. 2016), and Tierra del Fuego (Colonese et al. 2011.
Littoral or Maritime
Prehistoric coastal residents who exploited the sea can be defined as littoral, exploiting fish and shellfish resources available from the shore, or maritime, using seaworthy vessels to capture animals which do not come close to shore. Most maritime people also exploited the shore. In his 2016 article exploring shellfish use among Middle and Late Stone Age hunter-gatherers in South Africa, Jerardino provides an extensive review of the worldwide literature on littoral adaptations.
Littoral adaptations almost certainly preceded the evolution of Homo sapiens (Jerardino 2016; Klein and Bird 2016) in Africa and probably Europe. However, determining exactly when people began exploiting the resources of the sea is difficult due to the rising postglacial seas which have buried many coasts. At the Haua Fteah cave in Libya, shellfishing dates to the terminal Paleolithic Early Epipaleolithic, 17.2–12.5 kya (Prendergast et al. 2016). Along the Pacific Coast of North America, models of coastal immigration from Asia to the Americas suggest that the earliest migrants exploited shellfish and might have had a full maritime adaptation; however, the earliest dates, from San Miguel Island in California, are around 10 kya ( Braje et al. 2014). In Florida, the date of the earliest shellfish collectors is ca. 7000 ya (Saunders and Russo 2011).
In trying to understand Mesolithic coastal sites in western Scotland, Bonsall (1996) makes use of ethnographic data which indicate that the Australian Aborigines had three recognized types of shell middens: processing camps, where shellfish were removed from their shells and prepared for transport elsewhere; dinnertime camps, where people involved in other activities stopped, collected shellfish, and enjoyed a meal; and home bases. In Scotland, given the generally inclement weather, remnants of the first two types of camp would probably be found in shelters or other protected locales. Bonsall hypothesizes that the Obanian sites found around the western coast of Scotland are probably the remnants of processing and dinnertime camps occupied by gatherers whose base camps were located inland. The latter had a much richer artifact inventory, including the quintessential Mesolithic microliths, which are not found in the coastal sites.
In the much more complex society of Inka Peru, the fishermen of the Chincha Valley formed a separate community from the valley farmers and overlords whose protein they supplied. Specialized fishing communities seem to have existed in coastal Peru before the Inka took the area over and the Inka probably incorporated these communities into their empire with little change except for skimming the fish off for their own use rather than allowing the valley paramount lord to do so. The fishing here was primarily, if not entirely, littoral netting of small fish such as anchovies and anchovetas, which were then dried for exchange with other members of the valley and imperial communities (Sandweiss 1992).
The earliest known maritime adaptations in South America, and worldwide, come from sites in north-central Chile, where, between 7400 and 5900 cal BP, “not only were shallow waters and marine mammals exploited, but …a dedicated fishery for large pelagic fish existed; with indications suggesting that large swordfish, weighing up to 300 kg, were being caught and brought back complete to the settlement” as well as striped marlin, tuna, and amberjack (Bearez et al. 2016). Around 5000 BP, people bearing Arctic Small Tool Tradition implements entered Alaska and colonized the coast, developing a duel terrestrial/maritime economy (Tremayne and Winterhalder 2017). Around 3000 years ago, the residents of the Hoko River site in Washington state possessed a full-scale maritime adaptation. Due to half of the site being waterlogged, there is excellent preservation of organic artifacts, including numerous fishhooks, landing skids for canoes, pack baskets for transporting the fish, primarily halibut, and mats to protect the canoes and keep them from drying out between fishing trips. Around 3000 years ago, the site was seasonally occupied for a number of years, “mainly in the spring/summer season, when [the people] focused on offshore hook-and-line fishing for bottom fish, and particularly flatfishes” (Croes 1995, p. 229).
Many studies look at the relationships between coastal people and their inland neighbors, or between coastal sites and the inland sites which formed other parts of their seasonal round. Kennett and Voorhies used the oxygen isotope information from marsh clams, discussed above, to determine changes in the relationship between people and their environments. During the early late Archaic period, people collected clams year round, though they focused on the dry season.
“Through the late Archaic period, a general trend occurred toward wet season use of these locations. This culminated at the end of the late Archaic period with the exclusive use of the littoral zone during wet season months. These data indicate a fundamental shift in the way these estuarine locations were being used. We argue that people living in this region altered their overall subsistence strategy during the late Archaic period due to scheduling conflicts that occurred with the adoption of maize agriculture” (Kennett and Voorhies 1996, p. 689).
A similar process appears to have taken place in the Southeastern United States. Here ranked societies developed which took advantage of both coastal and interior resources. The origins of these societies are not well known, but evidence from Chesapeake Bay suggests that a pattern of springtime collection of oysters for local consumption was replaced, as maize arrived, with intensive spring harvesting and preserving of oysters. Anadromous fish and shellfish were major sources of protein along the coastal plain, where interior mammals such as white-tailed deer were rare. Farther south, in Florida, the development of the Calusa cultural pattern is very imperfectly known, but maritime and littoral resources were clearly of major importance (Waselkov 1997).
On the California Coast trade between the island and mainland sites intensified during the drought-stressed Transitional period (A.D. 1150–1300), when “islanders shipped millions of beads to mainland Chumash communities in exchange for many kinds of tools, services, and foods” (Arnold and Martin 2014).
On Kodiak Island, Alaska during the Kachemak period, the permanent settlements are on the shore and sites in the interior tend to be summer salmon fishing camps. The interior Outlet Site, while it was primarily a fishing camp, also showed evidence of fall/winter bird hunting and boasted substantial houses. Steffian et al. (2016) hypothesize that, as the population on Kodiak grew, the period of use of interior resources was extended and the coastal people, needing to lay stronger claim to their summer settlements, built substantial houses to serve as signs of ownership when they were absent.
Finally, returning to the Saloum Delta in Senegal (Hardy et al. 2016), it appears that the meat from many of the large shell middens was traded, processed, and dried, far into the interior.
Change in Coastal Adaptation
The majority of archaeological studies of coastal societies focus on change through time as people adjust to the constantly changing physical and cultural environment. Studies of the changing relationships between people and coasts have taken place in all parts of the world and only a few can be highlighted to give the flavor of current research on this topic.
The classic, and in many ways still unmatched study of human reaction to changing coastlines, is Shackleton’s study of Franchthi Cave in Greece (cf. 1988). During the 20,000 years the cave was occupied, sea level rose from −115 m to its present level. At varying times in the past, the shore in the vicinity of the cave supported different shellfish communities. By comparing the proposed communities to the shellfish remains in the cave, Shackleton was able to hypothesize that the people selectively gathered these resources rather than merely collecting the closest available species.
A short distance to the north of Franchthi Cave, near Volos, Greece, Zangger (1991) has studied changes in settlement along a prograding rather than submerging coastline. At ca. 6000 BP, Holocene sea levels reached their maximum height, and the shore in the vicinity of Volos was 3 km farther inland than it is today. Combined archaeological and geological investigation has shown that during the following 6000 years coastal cities followed the coastline as it prograded to the east.
In many urban coastal areas, engineers have captured land from the sea, using dikes and landfills to increase human living space. Nowhere did this process begin earlier or proceed further than in Holland. By 1984, Dutch archaeologists were already involved in detailed geoarchaeological studies looking at the changing relationships between people and the land. Brandt et al. (1984) showed how rising sea level changed the configuration of the land west of Amsterdam and, thus, its use by early settlers. By the early Iron Age, at least, human livestock was also changing the land, simplifying its ecology and creating a human-dominated landscape, a process that continued as people began to enclose the land with dikes.
On the Texas Gulf Coast, Archaic Period habitation closely followed relative sea-level rise. When sea-level rise was rapid, estuarine resources were impoverished, and humans abandoned the region. When sea-level rise slowed, “the emergence of highly photosynthetic bay/lagoon shallows support[ed] nutrient-rich shoreline vegetation [which] provided the basis for a rich, exploitable aquatic biomass” (Ricklis and Blum 1997, p. 287), which the people proceeded to exploit. In the past 10,000 years, this cycle repeated itself three times, with settlements between 7500 and 6800 BP, between 5900 and 4200 BP, and between 3000 BP and the late Prehistoric Period, and abandonments between 6800–5900 BP and 4200–5900 BP. During the first two occupations, the people focused on shellfish; during the course of the last ongoing sedimentation under conditions of stable sea level led to formation of the continuous modern barrier island chain by ca. 2500–2000 BP. As the disconnected barriers coalesced, backbarrier lagoons became extensive vegetated shallows, providing protective and nutrient-rich habitats for important fish species, with a resultant increase in estuarine fish biomass. A marked increase in fish remains in archaeological contexts, beginning at the time, indicates the emergence of intensive fishing as a major subsistence focus (Ricklis and Blum 1997, p. 306).
In Georgia, Turck and Thompson (2016) used a framework derived from Resilience theory to look at changes in adaptation as sea level dropped ca 5000 cal. BP, noting that while there were differences in adaptation between deltaic and nondeltaic environments, communities in both areas were resilient to change, partially through intervillage exchange between regions.
Short- and Long-Term Responses to Environmental Disaster
Many coastal changes are gradual and may take generations to make themselves felt. As Brandt et al. state, people “perceive slow, continuous changes as unchanged, as similar until so much change has occurred that it is clearly seen. Then, they … change… much more drastically than the circumstance requires” (1984, p. 14). Other changes, on the other hand, such as hurricanes, tornadoes, earthquakes, and tsunamis, are sudden, dramatic, and disastrous. Human response to sudden disaster varies according to the circumstances and can be looked at on various scales (Johnson 2002).
Two recent studies of North Pacific coastal peoples come to quite different conclusions concerning human response to catastrophic change. Jordan and Maschner (2000) have studied the western end of the Alaska Peninsula, where isostacy, eustacy, tectonics, and volcanoes have served as a dynamic stage for human settlement. The cultural phases they have identified mark changes in village organization and subsistence orientation in the area and reflect some combination of environmental, social, economic, and political change. The dominant factor in the environmental history of the area has been isostatic recovery, but Jordan and Maschner argue that two large or great earthquakes have had major effects on regional prehistory. The first, in ca. 2200 BP, led to coseismic subsidence which increased site erosion and submergence. No sites are dated in the area between 2400 and 2100 cal year BP suggesting that sites occupied shortly before the earthquake were destroyed and the area was abandoned for a century following the earthquake. In the following cultural period, there is a major change in village organization and subsistence. The most radical change in village organization took place about 850–950 cal year BP in concert with changes in almost all the eastern Aleutian arc. There does not seem to be any local environmental instability correlated with these changes. However, there was a great earthquake in the Gulf of Alaska between 700 and 900 BP. Environmental recovery probably took a relatively short period, but cultural disruption may have lasted considerably longer. Jordan and Maschner argue that the displacement of populations from the region of the epicenter may have triggered the cultural changes in the wider area.
On the south side of the Alaska Peninsula, Johnson does not see as strong a reaction to catastrophe. The initial occupation of the islands appears to have been rapid, following a major uplift episode, which substantially increased terrace living space in the islands. The immigrants may have been fleeing from areas where the effect of the earthquakes was subsidence rather than uplift. Johnson concludes that “for maritime hunter-gatherers like the Shumagin Islanders, earthquakes are terrifying occurrences which may slow cultural development and force populations to move their settlements, but they do not seem to have a major effect on cultural development. Shumagin history, like ours, is more affected by human events than by natural events, however catastrophic” (Johnson 2002).
Archaeology in Service to Geology
While archaeologists most often use the results of other scientists to help interpret their sites, occasionally archaeological data are used to help interpret geological data. The majority of these studies concern sea-level change. Since people do not live underwater, sites found beneath the sea are clear evidence of rising sea level or sinking land; sites with a clear maritime focus located well away from the shore, on the other hand, indicate lowered sea level or rising land. These sites can often be dated, using either cultural or geophysical means, with more precision and certainty than natural deposits, allowing geologists to pinpoint the changes of interest to them more precisely.
In a major review, Owen Mason (1993) looked at the geoarchaeology of beach ridges (q.v.) and cheniers on prograding coastlines worldwide. He looked at studies in which archaeologists and geologists working cooperatively achieved a thorough understanding of the chronology of these features as well as those in which a lack of cooperation between the two has led to less satisfactory results for both. In using archaeological sites to date beach ridge formation, one must first carefully evaluate cultural adaptation of the past people to be certain that site location is closely tied to the position of the sea relative to the inhabited ridge.
An example of the study of rising sea levels is that of Morhange et al. (1996), which used archaeological, biological, and sedimentary data to model the sea level at Marsielles over the past 4000 years. In this area, the archaeological indicators of sea level include objects such as wrecks, which were originally deposited below sea level, the walls of quays and wharf pilings found at sea level, and roads and room floors which were originally above sea level. Using these urban features in combination with barnacles and beach indicators led to a detailed and well supported sea-level record. On a much broader scale, Flemming (1998) reviews drowned sites worldwide that indicate Paleolithic, Neolithic, and Bronze Age sea levels.
Archaeological sites can also provide evidence of falling sea level. In a noncivilized, shell midden context on the Northwest Coast, Cannon (2000) used coring to recover samples from the surface to the base of the cultural deposits in a series of sites. By dating the basal cultural deposits and establishing their relationship to present sea level, he was able to identify steady sea level decline over the past 10,000 years in this region.
Relative sea levels may also change in a complex and irregular manner. In the Shumagin Islands, Alaska, where episodic tectonic uplift is coupled with interseismic downwarping and postglacial sea-level rise over the past 10,000 years, archaeological site locations served to constrain geological modeling, since occupied sites could not be located underwater (Winslow and Johnson 1989).
Sclerochronology and oxygen isotope studies have provided major insights into climate change through time (Andrus 2011). Among recent studies, four looked at areas of the Atlantic. Helama and Hood (2011) used sclerochronology in combination with older methods to study a midden in north Norway, attributing the observed changes to the North Atlantic Oscillation. Also in 2011, Wannamaker and colleagues used oxygen isotope values of shells to examine changes in seawater temperatures during the Medieval Climate Anomaly and the Little Ice Age. In 2012, two articles came out using oxygen isotope ratios to examine climate change in Scotland. Wang et al. looked at climate changes between the Neoglacial and the Roman Warm Period in northwest Scotland, while Surge and Barrett discovered higher seasonality and cooler winters during early medieval times on Orkney.
In the eastern Pacific Ocean, Carré et al. (2014) used oxygen isotope variation to reconstruct the El Niño–Southern Oscillation (ENSO) for the past 10,000 years using mollusk shells from middens in Peru.
Book-length compilations in English have recently appeared on the Indo-Pacific (Ono et al. 2014), Europe (Milner et al. 2007), Northwest Coast of North America (Fedje and Mathewes 2005; Moss and Cannon 2011), California (Arnold 2004; Raab et al. 2009; Jones and Waugh 1995), Southeastern US ( Dunbar 2016; Marquardt and Walker 2013), Mexico (Foster 2017), Shetland Island (Moore and Wilson 2014), Ireland (O’Sullivan and Breen 2017), and Maine (Bourque 2012). In addition to these areal studies, there have also been a number of topical books: Human Impacts (Rick and Erlandson 2008), Cultural Dynamics of Shell Midden Sites (Roksandic et al. 2014), Shells as Coastal Resources (Bailey et al. 2013), Paleolandscapes of the Continental Shelf (Bailey et al. 2017; Evans et al. 2014), Building Reslience (Van de Noort 2013), Archaeology of Maritime Landscapes (Ford 2012), and Changing Coastlines (Bicho et al. 2011).
Finally, Archaeolomalacology (2005), edited by Daniella Bar-Yosef Mayer, presents articles about sites from the Americas, Europe, and Asia which discuss various uses of shellfish and their shells.
The North Pacific coast of North America and the Channel Islands and adjacent coast of California are areas that have seen intensive research on coastal adaptations.
Integrated studies of North Pacific prehistory are descendants of the nineteenth-century studies of Arctic cultures crystallized in Gjessing’s formulation of the Circumpolar Stone Age concept. Early studies of northern maritime adaptations were much too broad and general and have been replaced by more focused studies of particular regions. In the north Pacific, the opening of the “Ice Curtain” led to increased contact between New World and Russian archaeologists interested in the North Pacific. As these studies progressed, links to more southern Pacific cultures became obvious, drawing in Japanese scholars, who have studied both their own and New World cultures. A major focus of these studies has been the inhabitation of the Americas in the terminal Pleistocene Epoch (q.v.) (Erlandson et al. 2007; Erlandson and Braje 2011). Additional studies have been concerned with the issues of culture contact and influence around the North Pacific Basin, with initial adaptations to the coastline, both littoral and maritime, and with interrelationships between Pacific coastal peoples and their interior neighbors (Campbell and Butler 2010a). The question of the degree to which Northwest Coast people managed their resources has come to prominence in the last few years (Jackley et al. 2016), as has the resilience of Northwest Coast adaptations to climate change (Campbell and Butler 2010b). See also the books mentioned above.
A nearby area in which there has been an explosion of archaeological research in the last few decades is the Channel Islands area in southern California. In this region, prehistorically, there was a mainland adaptation, which often, if not always, included both coastal and inland facies, and an island adaptation, which, perforce, was always primarily littoral or maritime, though sometimes provided with inland resources through trade with the mainland people. Archaeologists and geologists working in this area have been trying to determine environmental changes in the area, how these changes affected the marine and shore-based resources, and what effect these changes had on cultural development and change. Also of concern is whether the whole area can be treated as a unit for paleoecological and paleocultural studies or whether subdivisions, between the southern and northern islands or between the islands and the mainland, are significant enough to make conclusions derived from one zone inapplicable in the other. In the process of arguing these various positions, local scholars have significantly advanced our understanding of the factors involved in both ecological and cultural development in highly variable coastal environments (cf. Kennett and Kennett 2000).
These studies have continued apace. In addition to the ones noted in various sections above, there are Reeder-Myers’s (2014) study asking why variation exists in the islands, Glassow’s (2015) study of red abalone middens, Jazwa et al.’s (2015) study of resource and settlement variability on the northern islands, and Jones et al.’s study of various marine resources (2016), and later (2017) study of Morrow Bay on the mainland as a refugium during the Medieval Climatic Anomaly.
“Interdisciplinary efforts to reconstruct shoreline history and associated environmental parameters could significantly raise the potential of locating early postglacial archaeological sites” (Fedje and Christensen 1999, p. 650). More modeling of past environments, both on large- and small-scales, is necessary, as well as additional detailed studies of regions and sites. More bathymetric studies are needed in many areas: in coastal Alaska, for example, bathymetric charts are very general and not useful for detailed coastal studies, even where they do not meander off into dotted lines. Given the maritime focus that the majority of coastal peoples developed, sooner or later, and the freedom of movement boats provided, regional studies are essential (Waselkov 1997). As detailed understanding of local sea level variation increases, we will be better able to understand how prehistoric people adapted to and used these changes in cultural development.
Absence of evidence is not necessarily evidence of absence, particularly in coastal environments. A dictum all coastal archaeologists should repeat when going to bed and upon arising in the morning: Consider the absent! In modeling past coastal subsistence/settlement systems, archaeologists must take account of sites that are gone! What we don’t know will hurt us! Archaeologists should use all methods available, particularly modern tools like Geographic Information Systems (q. v.), to predict site loss and to get a handle on how much of the archaeological record is actually left in any particular area. Prehistoric coastal peoples saw their settlements disappear in storms just as present coastal people do, and the effect of these disappearances on the archaeological record is something coastal archaeologists ignore at their peril.
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