Applying luminescence dating of ceramics to the problem of dating Arctic archaeological sites

Journal of Archaeological Science 112 (2019) 105030

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Applying luminescence dating of ceramics to the problem of dating Arctic archaeological sites Shelby L. Anderson a, *, James K. Feathers b a b

Portland State University, Department of Anthropology, P.O. Box 751, Portland, OR 97207, USA University of Washington, Department of Anthropology, P.O. Box 353100, Seattle, WA 98195-3100, , USA

A R T I C L E I N F O

A B S T R A C T

Keywords: Chronology Luminescence dating Ceramics Arctic

Dating Arctic archaeological sites is challenging because of limited terrestrial bone and the high probability of old wood in northern regions. Luminescence dating of ceramic materials, abundant in western Arctic late Ho­ locene archaeological sites, offers another potential source of chronological information. We set out to evaluate whether luminescence can provide chronological information in one particular region. We obtained lumines­ cence ages on 14 pottery samples from seven study sites located on the coast and interior regions of northwest Alaska. Twelve of the luminescence dates are in accord with radiocarbon, tree ring, and artifact data from the study sites. Results indicate that all of the study sites may be older than previously established, suggesting previously unknown early Thule or Birnirk occupation of the coast and interior of northwest Alaska. We conclude that luminescence dating of ceramic materials from this region is possible and can complement other dating methods that are more widely accepted in the western Arctic. There is considerable potential through future applications of luminescence dating for improving northeast Asian and Arctic chronologies and expanding our understanding of circumpolar Holocene migration, cultural interaction, and change.

1. Introduction

materials contaminated by marine mammal oils tend to date older than terrestrial samples due to the marine reservoir effect (e.g. Dumond and Griffin, 2002; McGhee and Tuck, 1976). Friesen and Arnold (2008; see also McGhee, 2000; Morrison, 2001) argue that terrestrial mammal bone yields the most accurate and precise radiocarbon dates for Arctic sites; unfortunately, terrestrial bone is often rare at coastal sites and can sometimes yield δC13 values similar to marine species (Jensen, 2009b:192–193). This could be due to the consumption of beach scav­ enged marine fish, mammals, and vegetation by caribou, fox, and other terrestrial species. In general, Arctic archaeologists avoid marine bone when dating sites. Tree ring dating is possible in northwest Alaska as there is an existing 350 year master chronology (Giddings, 1940, 1941, 1942, 1948, 1952b). Unfortunately, tree rings dates are subject to many of the same problems as radiocarbon dating wood in Arctic contexts (e.g. old wood, association between dated and target event, etc.). These problems limit the materials available for radiocarbon dating in Arctic settings (see Blumer, 2002 for additional summary). However, in northeast Asia and the western North American Arctic, ceramic vessels and lamps could be dated using luminescence techniques. Ceramics are present beginning around 16,800–14,100 cal BP in the Russian Far East of northeast Asia (Kuzmin, 2013). In northern Alaska, ceramic material

Dating archaeological materials in the Arctic, particularly in coastal areas, offers challenges in addition to those usually faced by archaeol­ ogists. Most Arctic sites are located in tundra regions where wood ma­ terials are sparse and are often limited to driftwood, dwarf willow, and dwarf birch species, which can be surprisingly long lived (e.g. Arundale, 1981; McGhee, 2009:157). Wood used in house construction was probably carefully collected and re-used over time, enhancing the pos­ sibility that dates – either radiocarbon or tree-ring – on structural wood can be much older than the house occupation of interest; while this behavior is not unique to the Arctic, excellent wood preservation in this environment means that older wood is more frequently preserved. Large pieces of driftwood could circulate the ocean for a period of time before being deposited on a beach where they could remain untouched for centuries before being collected and used in house construction (Alix, 2005; Giddings, 1952; Jensen, 2009,Jensen, 2009b:52). Archaeologists have focused on dating charcoal from local short lived species like birch or alder, but this material is not always abundant. Alternatively, bone or ivory can be dated, but a suitable correction factor for the marine reservoir effect is typically not available; marine mammal bone and

* Corresponding author. E-mail addresses: [email protected] (S.L. Anderson), [email protected] (J.K. Feathers). https://doi.org/10.1016/j.jas.2019.105030 Received 7 January 2019; Received in revised form 22 August 2019; Accepted 4 October 2019 Available online 24 October 2019 0305-4403/© 2019 Elsevier Ltd. All rights reserved.

S.L. Anderson and J.K. Feathers

Journal of Archaeological Science 112 (2019) 105030

is present as early as about 2500 years ago, and is common in northern Alaska and the western Canadian Arctic after about 1000 cal BP when ~ upiat and Inuit people, the Birnirk and Thule the ancestors of modern In peoples, rapidly migrated across the North American Arctic. Lumines­ cence dating has seen minimal exploration in the Circumpolar North, particularly with respect to dating pottery (e.g. Kuzmin et al., 2001; Sheehan, 1982). In this paper, we explore the potential of pottery luminescence dating for dating late Holocene archaeological sites in the Western North American Arctic, using thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). We focus on seven sites located in northwest Alaska, on the Kobuk River, the Kotzebue Sound coast, and the interior of the Seward Peninsula (Fig. 1). These sites were selected because they are dated by tree rings (Giddings,

1952b; VanStone, 1955) and more recent radiocarbon dates (Shirar, 2011). In addition, archaeologists made major collections at these sites in the 1940s and 1950s. Pottery luminescence dates could improve the existing chronology because luminescence dates are not subject to the same problems of old wood as tree ring, andwood or charcoal radio­ carbon dates. Luminescence dates could yield a refined chronology for this region for a critical time period when the ancestors of modern ~ upiat and Inuit people (Birnirk and Thule peoples) spread eastward In rapidly from the Bering Strait region across the North American Arctic. While the broad timing of this migration is established, many questions ~ upiat and Inuit culture remain about the specifics of where and when In emerged (Friesen, 2016:681; Mason, 2016), why it spread (Friesen and Arnold, 2008), and the nature of interactions between the colonizing populations and other inhabitants of the western and eastern North

Fig. 1. Study area and sites located in northwest Alaska (Figure by Justin Junge). 2

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Journal of Archaeological Science 112 (2019) 105030

American Arctic (e.g. Ipiutak, Dorset cultures) (e.g. Friesen, 2016; Park, 2016; Raghavan et al., 2014); new dates and dating methods for this critical transitional period could resolve some of these questions. This work has several broader implications. Much Arctic pottery is low fired and our project addresses how much of an obstacle that might be at our selected sites. Reasonable results might encourage more widespread application of luminescence dating in the Arctic. The cur­ rent northeast Asian-Alaskan chronology is based primarily on radio­ carbon dates (although see Kuzmin et al., 2001) and focused on the earliest sites in the Sub-Arctic or Northeast Asian; there are data gaps in the chronology of northern Northeast Asia, the Bering Strait, and western Alaska (e.g. Kuzmin, 2010, 2013; Hommel, 2010). While organic temper can be radiocarbon dated in some northeast Asian con­ texts (Kuzmin et al., 2001), it is not possible in the North American Arctic where most pottery is fired at high enough of a temperature that the organic component is gone; in either context, luminescence dating would help refine regional chronologies. Improved dating of Northeast Asian and Northern Alaskan pottery could link the invention and spread of hunter-gatherer ceramic traditions in Northeast Asia to those in the North American Arctic (Jordan and Zvelebil, 2010; McKenzie et al., 2010). Furthermore, luminescence dates directly on pottery from these regions would inform our larger understanding of cultural interaction, evolution, and transmission across the Northeast Asian and North American Arctic (e.g. Cooper et al., 2016; Mason, 1998). Our project is an initial attempt to apply luminescence to regional ceramics for the purpose of establishing whether or not further application of lumines­ cence to Arctic ceramics would be productive. This is an important and necessary first step towards the broader application of luminescence dating of ceramics in the North American Arctic. In support of this goal, our discussion of results focuses both on the strengths and limitations of our work, while also considering potential implications of the dates themselves for circumpolar pre-contact chronology.

bush/tree) to when a house was constructed (the target event) relies on a series of assumptions about human behavior, stratigraphy, and context. Luminescence dating avoids many of these assumptions, and can also be applied to material that is often abundant in the archaeological record, e.g. ceramics or sediments (Feathers, 1997). Ceramic luminescence dates do have disadvantages in an Arctic context. Dated ceramics could have been made prior to the occupation of a particular feature or site and brought to the site later; while this could result in erroneously old dates, it is unlikely ceramics will significantly pre-date house occupation as the low durability of post-1500 ceramics means that ceramics were not curated for long periods of time. It is also possible that younger ceramics could infiltrate houses after abandon­ ment through both natural and cultural processes. This is particularly problematic in the case of dating collections made in the mid-20th century as archaeologists did not retain contextual information beyond the house/feature level. In contemporary excavations, this problem can be mitigated by retaining contextual information, and by dating ceramics found on occupation floors and not from feature fill deposits that are associated with post-occupation cultural and natural processes. A third problem is that Arctic ceramics tend to be low fired, and some may not have been fired high enough (generally about 500 � C) to reset the luminescence signal (Spencer and Sanderson, 2012). Other technical issues include the need for minerals within the ceramic having suitable luminescence characteristics and an accurate estimation of a wide array of variables that must be controlled to determine a date. The University of Washington laboratory processes a large number of ceramic samples (~50-per year), much of it rather routinely, and only a few are found not to be datable. Of 71 samples received in the last two years, dates have been obtained or expect to be obtained (where the analysis is started but not completed) on all of them. The complexity of the dating process also allows internal evaluation of the reliability of the date (Feathers, 2009). What is obtained is not just a number, but a data structure. Despite the potential of luminescence dating, its application on ce­ ramics in the Arctic is very limited. To our knowledge, there is only a single project and associated report that involved luminescence dating Arctic ceramics (Sheehan, 1982). Sheehan submitted several sherds to Alpha Analytic, a lab no longer in existence. The work, done before modern methods were developed, was deemed unsuccessful, although a couple of dates were obtained. The reason cited was insufficient firing, due to a lack of temperature plateaus. This is not a serious problem with the ceramics analyzed here as detailed later. Luminescence has also been used to date sediments in central and southcentral Alaska (e.g., Reuther et al., 2016; Wygal and Goebel, 2012), for the most part quite successfully.

2. Background 2.1. Luminescence dating Luminescence dating works on a wide range of sediment, rocks, and ceramic materials. It measures the time that has passed since these materials were last exposed to sufficient heat or light. The method is based on the ability of some minerals, principally quartz and feldspar, to absorb and store energy from natural radioactivity. Natural radiation causes atoms within the crystal lattice to ionize and freed electrons (and the corresponding electron vacancies) are trapped in locally chargedeficient defects within the crystal structure. Depending on the amount of energy required for release, the trapped charge potentially remains in the trap indefinitely, until it is released by heat or light. The amount of stored energy is measured by calibration of luminescence signals against those induced by laboratory doses as a quantity called equivalent dose (De). Dividing by the dose rate (the rate at which natural radiation is delivered to the sample) yields an age in calendar years. In measuring De, stimulation of the luminescence signal can either be done by heat (thermoluminescence, TL) or by photons (visible light producing optically stimulated luminescence (OSL) or infrared light producing infrared stimulated luminescence (IRSL)) Although the method was developed in the context of dating pottery, most research now is in dating sediments or rocks. Most analysis is also done with OSL and IRSL, including on ceramics (see various reviews in Rink and Thompson, 2015). Specific reviews on luminescence dating ceramics include Feathers, 2009 and Bailiff (2015). In the case of ceramics, a strength of the method is the potential for directly dating the target event, i.e. when a ceramic vessel was fired, and avoiding complex bridging arguments that are often necessary to link a target event to the dated event (Feathers, 1997) when using other dating methods. For example, associating the radiocarbon date obtained from a small twig found in an Arctic house (the dated event, death of the

2.2. Northern hunter-gatherer pottery There are two major pottery traditions in northwest and northern Alaska, pre-1500 cal BP or Early Arctic pottery (formerly Paleoeskimo pottery; associated with Choris and Norton phases) and post-1500 cal BP Late Arctic pottery (formerly Neoeskimo pottery; associated with Bir­ nirk, Thule, late Thule, and historic phases). There are various hypoth­ eses about why Early and Late Arctic pottery traditions differ, including cultural difference, different food processing practices, changing use of fuels, and shift from use as prestige items to every day utilitarian cooking vessels (Ackerman, 1982; Anderson et al., 2017; Frink and Harry, 2008). Both traditions were brought to Alaska as part of migra­ tions across the Bering Strait. The earliest pottery in Alaska dates to approximately 2500 years ago and is associated with the Choris Phase (Table 1). Early pottery vessels have a rounded base, are thin-walled, and are cord or check marked (Fig. 2). Early ceramics are quite rare, and may have been a prestige item (see Anderson et al., 2017 for full discussion).They are distributed across northern Alaska, as far as the Engigstciak site located on the Firth River in the western Canadian Arctic, and also south into western and southwest Alaska (Fig. 3). 3

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Journal of Archaeological Science 112 (2019) 105030

Table 1 Cultures of northwest Alaska and Bering Strait regions.

Early Arctic Pottery

Late Arctic Pottery

Cultures

Approximate Established Age (cal BP)

Geographic Range of Culture

References

Denbigh

4500–2750

Kotzebue Sound, Brooks Range

Choris Norton (Near Ipiutak in Northwest Alaska) Old Bering Sea Okvik Ipiutak

2750–2450 2500–2000a

Kotzebue Sound, Brooks Range, northern Yukon Territory Southern Alaska to western Canadian Arctic.

Buonasera et al. (2015); Tremayne (2015) Mason (2009) Dumond (2000); Mason (2009)

2150–750 1750–1550b 1750–1150

Birnirk Punuk

1350–750 1150–550

Thule Kotzebue

950 to contact era 770/550 to contact era 750-550 (Early) 550 to contact era (Late)

Western shore of Chukchi Sea and Bering Strait Islands Western shore of Chukchi Sea and Bering Strait Islands Norton Sound to Point Barrow, interior of Northwest Alaska and Brooks Range Eastern and western shores of Chukchi sea, Bering Strait Islands Western shore of Chukchi Sea and Bering Strait Islands, limited distribution in mainland northwest Alaska Bering Strait to Greenland Coastal areas of Northwest Alaska

Arctic Woodland

a b

Interior areas of Northwest Alaska

Mason (2009) Mason (2009) Mason (2009) Mason (2009) Gerlach and Mason (1992); Mason (2009) Mason (2009) Giddings (1952b); Schaaf (1988); VanStone (1955) Giddings (1952b); Schaaf (1988);

2400/2300–1000 cal BP in western and southwest Alaska. 2550–2350 cal BP in Chukotka. Fig. 2. Examples of Early (pre-1500 cal BP) (A – Check stamp [NPS BELA 4-424a], B – Linear stamp [NPS BELA-4-471]) and Late (post-1500 cal BP) Arctic Pottery (C – Curvilinear stamp [UA 1-19412271], D-Large check stamp or waffle stamp [UA6782-KTZ-H8-51], E-Scratched/scraped [UA 1-19412474], F-Textile impressed [UA67-82-H10-3], GStriated with Pie crust rim [UA 1-1941-2901]) ceramic technology (Figure by Justin Junge) (Im­ ages D-G Courtesy of the University of Alaska Museum of the North and Bureau of Land Management).

Post-1500 cal BP pottery is more abundant and has a wider distribution ~ upiat migrants into this region (Fig. 3). After 1500 cal BP, the first In (Birnirk peoples) brought this new ceramic tradition into Alaska, with the earliest Birnirk cultural sites dating to approximately 1350 cal BP in mainland Alaska. Late Arctic ceramic technology quickly spread as de­ scendants of the Birnirk people, the Thule, rapidly spread across the circumpolar north and into southwest Alaska. Thule ceramics are found across coastal and coastal margin areas of southwest, western, and northern Alaska, and the western Canadian Arctic; there are also eastern

Canadian Arctic Thule sites with ceramics but the technology is replaced with steatite vessels for the most part in the eastern Canadian Arctic (Arnold and Stimmell, 1983). Late Arctic pottery vessels have flat bases, are thicker than Early Arctic pottery, and were fired at lower tempera­ tures. There are a diversity of Thule decorative types that vary regionally but the majority of vessels dating to the Late period are undecorated. Clay lamps are also known during the Thule period; their distribution is similar to ceramic vessels (de Laguna, 1940; Oswalt, 1953). Temper types vary across traditions and from region to region (Anderson et al., 4

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Journal of Archaeological Science 112 (2019) 105030

1 R U S S I A

2

C A U N S A A D A

3 65

8 9

7 4

10 ALASKA

LEGEND

11

Study Site

Other Site

Late Arctic Pottery (post-1500 BP) Early Arctic Pottery (pre-1500 cal BP)

SITES

0

100 200

400

Kilometers

1 2 3 4 5 6 7 8 9 10 11

Engigstciak, Firth River Lake Kayak Maiyumerak Black River Ambler Island Onion Portage Ahteut Ekseavik Kotzebue Cloud Lake Village Iyatayet, Madjujuinuk

Fig. 3. Approximate known distribution of Early and Late Arctic pottery (Figure by Johonna Shea).

Table 2 Overview of site ages as established prior to the current project. Name

Dating Method

Approximate Age Rangea

Dating Method

Approximate Age Range Based on Compiled Radiocarbon Datesb

Cultural Attribution

References

Ahteut (XBM 2 and 3)

Tree Ring

750-700 cal BP/ AD 1200–1250

Radiocarbon

900-680 cal BP/ 1060–1270 cal AD

Giddings (1952b); Shirar (2011)

Ambler Island (AMR 2 and 6)

Tree Rings

250-190 cal BP/ AD 1700–1760

Radiocarbon

510 cal BP -modern era/ 1440 cal AD – modern era

Black River (SHU 22)

Relative dating, similar age or slightly older than Ambler Island Tree Rings

250-190 cal BP/ AD 1700–1760

n/a

n/a

Early Arctic Woodland (EAW) Late Arctic Woodland (LAW) LAW

570-520 cal BP/ AD 1280–1430

Radiocarbon

780-550 cal BP/1170-1400 ADc

EAW

Tree Rings

770-370 cal BP/ AD 1180–1580

Radiocarbon

1390 cal BP – modern era/ 558 AD – modern era

Late Thule/ Kotzebue

Relative dating

570-520 BP/AD 1280–1430 18th-19th century

Radiocarbon

1520-740 cal BP/430-1214 AD n/a

EAW

Giddings (1952b); Graumlich and King (1997); Shirar (2011); see also Rainey and Ralph (1959) Giddings (1952b), VanStone (1955), Odell et al. (2015); Shinabarger (2014) Anderson (1988); Giddings (1952b)

Ekseavik (XBM 9 Kotzebue (KTZ 30, 31, 36, 346, 347) Onion Portage (AMR 1) Cloud Lake Village (BEN 33) a b c

Relative dating

n/a

Late Thule/ Kotzebue

Giddings (1952b); Shirar (2011) Giddings (1952b)

Adams (1977); Powers et al. (1982)

See Supplement 1 for all tree ring ages. All dates calibrated in Oxcal 4.3 (Ramsey, 2009) with IntCal 13 (Reimer et al., 2013). See Supplement 2 for all radiocarbon dates. Date range does not include Rainey and Ralph (1959) dates due to large error on solid carbon dates. 5

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Journal of Archaeological Science 112 (2019) 105030

2017). Our current project is focused on a sample of Late Arctic pottery vessels from northwest Alaska. A primary concern at the outset of this project was whether or not these ceramics were fired at high enough temperatures to reset the luminescence signal. Ethnographic and archaeological discussions of ceramic firing techniques (e.g. Fienu­ p-Riordan, 1975; Geist and Rainey, 1937; Nelson, 1983; Oswalt, 1952; Sipary, 1984; VanStone, 1989) indicate that pottery was typically fired at low temperatures next to, or in, open fires. An examination of a large sample (n ¼ 8393) of northwestern Alaskan ceramics (Anderson, 2011) suggests that the majority were fired or partially fired at low tempera­ tures. Based on this analysis, we selected samples that we thought were sufficiently fired from several key sites to luminescence date.

retrospect, this is not surprising given that the tree ring ages were from a relatively small number of houses within each site (Supplement 3). For example, Ahteut has an estimated 33 houses, one was tree ring dated and an additional house was radiocarbon dated. The Kotzebue site is esti­ mated to have had approximately 230 houses (Junge, 2017); Giddings dated just 15 by tree rings and none by radiocarbon dating; more recently, Odell et al. (2015) and Shinabarger (2014) dated additional features at the site (Supplement 3). Radiocarbon dating raised questions about the antiquity of these sites, specifically the potential for older components with connections to the earliest expansion of Birnirk or Thule peoples (Table 1) into the region. Luminescence dates provide an additional source of chronological information for these key sites, which could have larger significance for understanding the late Holocene spread of Thule peoples from the coasts of the Bering Strait across the North American Arctic.

3. Northwest Alaska study sites Luminescence samples were chosen from ceramic assemblages at eight sites, located on the Kobuk River, central coast of Kotzebue Sound, and the interior of the Seward Peninsula (Fig. 1, Table 2). All of the study sites are village locations made up of five or more houses that were occupied semi-permanently, primarily during the cold season. In the summer, people would travel more extensively and move their resi­ dences to a variety of logistical camps located near fishing, hunting, and gathering grounds (see Anderson and Freeburg, 2014; Burch, 1998). The Kotzebue site is the largest of our study sites although it is now heavily disturbed by development of the modern community of Kotzebue. The Kotzebue and Kobuk River sites are well dated for northwest Alaskan sites. Giddings obtained multiple tree-ring samples from house features at these sites, and constructed a chronology for this region (Giddings, 1940, 1941, 1942, 1948) (Table 1, Supplement 1). VanStone (1955) augmented Giddings’ chronology for the Kotzebue site. Giddings also had several samples from the Ekseavik site radiocarbon dated (Rainey and Ralph, 1959); this was in the early years of applying radiocarbon dating to archaeological contexts. These dates, obtained using the solid carbon method, were considered unreliable by the original analysts (Rainey and Ralph, 1959: 365) and are excluded from this analysis. Graumlich and King’s (1997) reanalysis of Giddings tree ring samples pushed the age for Ekseavik House 11 back from AD 1300 to AD 1279 (Shirar, 2011; 11). More recently, several researchers ob­ tained radiocarbon dates for the Kobuk and Kotzebue sites (Odell et al., 2015; Shinabarger, 2014; Shirar, 2011) (Table 1, Supplement 2). The Kobuk radiocarbon dates (Shirar, 2011) were obtained on organic ma­ terials from the same collections as the ceramic materials, collected by Giddings (1952b) and therefore have the same level of minimal contextual information; provenience information is limited to the house/feature level. Prior dates for the study sites (with the exception of Cloud Lake Village) are the basis for the regional late Holocene chronology. Gid­ dings (1952b) tree ring dated the Ahteut, Ekseavik, and Onion Portage sites to the early Arctic Woodland period, while the Ambler Island and Black River sites were thought to be later Arctic Woodland (Table 2). The Arctic Woodland and Kotzebue periods are terms for Thule phase sites in northwest Alaska (Table 1). Thus, early Arctic Woodland or early Kotzebue period sites can be considered early Thule sites. Giddings originally sub-divided the Kotzebue site complex into the Old and In­ termediate Kotzebue sites, but additional tree ring dates obtained at Kotzebue by VanStone (1955) indicate that occupation of the Old and Intermediate sites overlapped so the distinction is not meaningful. The Cloud Lake village site was relatively dated to the late pre-contact period, which is often referred to as the late Kotzebue period on the coasts of northwest Alaska. Subsequent radiocarbon dating at several of the study sites (Table 2) yielded older ages for several of the tree ring dated features (Odell et al., 2015; Shinabarger, 2014; Shirar, 2011) and for previously undated features, suggesting that these sites have older components than originally thought (see Shirar, 2011 for an in-depth discussion of tree rings and radiocarbon date comparisons). In

4. Methods 4.1. Sample selection and collection A total of 14 samples for luminescence dating were selected from features at the study sites that were undated or minimally dated, that also yielded large pottery assemblages. Sampling was designed this way to expand our understanding of site chronology and also to better date specific ceramic assemblages so they could be used in a regional sourcing study (Anderson et al., 2011, 2016). The degree of ceramic firing determined by hardness and size were also considerations in sampling; we selected sherds at least 2 cm in diameter and 5 cm thick to ensure enough sample for analysis. Ceramics were collected from most of the study sites in the 1940s and 50s (Giddings, 1952b; VanStone, 1955) and provenience information is limited to the house level; there is no contextual information associated with the sherds themselves. Additional research was carried out at the Onion Portage site in the 1960s and 70s, but these collections are not available for analysis and data from the more recent components at Onion Portage are not pub­ lished (although see Anderson, 1988). Some contextual information is available for the Cloud Lake Village assemblage, which was collected in 1975 (Adams, 1977; Powers et al., 1982). All of the collections are currently stored at the University of Alaska Fairbanks Museum of the North (UAMN). At the time samples were selected for luminescence analysis the sherds were stored in an assortment of cardboard boxes and paper bags, in metal or plastic drawers; they were kept in the museum climate controlled storage facility. Because all the selected ceramic samples lacked depth information, ceramic sample depth was estimated as the total depth of cultural ma­ terial reported or measured by S. Anderson for each feature or site (Table 3). Stratigraphic information was not available for any of the features beyond conceptual drawings for a few features that include coarse depth information (i.e. approximate depth of feature floor). In some cases, we were able to relocate specific features during fieldwork. None of the features were backfilled by the original excavators, so we were able to collect measurements on maximum excavated depth in some cases. We used both field observations and published information about site stratigraphy to estimate sherd depth and site sediment texture (see Table 3 for additional depth details). Original excavators did not collect sediments in association with ceramic samples; there were no sediment samples (ceramic associated or otherwise) available from any of the study sites. This is not surprising given that excavations took place over 50 years ago in most cases. To address this, fieldwork was undertaken to collect associated sediment samples for gamma dose rate estimations from the study sites. Existing maps, unpublished site information and maps from the National Park Service archives, and site documentation at the UAMN were used to relocate sites and features across several remote areas of Northwest Alaska. Planned work at Cloud Lake Village could not be completed because the lake could not be accessed by float plane (see Anderson, 6

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Journal of Archaeological Science 112 (2019) 105030

Table 3 Sherd contextual information. Sample

Site

Accession

Sherd No.

Pottery Decorative Type

Feature

Cultural Affiliation

Site Area (m2) Estimate

Estimated Sherd Depth (m)

Site Sediment Texture

Comments

UW2336

Ekseavik

1–1941

141

Plain

House 5S

EAW

Unknown

0–2 m

Sandy

UW2337

Kotzebue

1–1947

2115A

Plain

House 10

Kotzebue

Unknown

0–2 m

Sand and gravel

UW2338

Ambler Island

1–1941

2483

Plain

House 3

LAW

6720

0–.61 m

Sandy

UW2339

Ambler Island

1–1941

2480

Plain

House 7

LAW

6720

0–.91

Sandy

UW2340

Ahteut

1–1941

2348

Plain

House 2S

EAW

60,900

0–1.37 m

Sandy

UW2341

Ahteut

1–1941

2119B

Plain

House 10S

EAW

60,900

0–1.83 m

Sandy

UW2342

Ahteut

1–1941

2168

Curvilinear Stamp

House 12S

EAW

60,900

0–1.98

Sandy

UW2343

Ahteut

1–1941

2086

Plain

House 6AS

EAW

60,900

0–1.37

Sandy

UW2344

Ekseavik

1–1947

1854

Plain

House 10

EAW

Unknown

0–2 m

Sandy

UW2345

Ekseavik

1–1941

308

Striated

House 4

EAW

Unknown

0–2 m

Sandy

UW2346

Onion Portage

1-1941 (28)

3635

Plain

House 1

EAW

17,500

0–2 m

Sandy

UW2347

Black River

1–1941

2530

Plain

House 3

LAW

13450

0–1 m

Sandy

Estimated sherd depth based on observed total depth of feature during summer 2010 site visit, and on simple stratigraphic drawings in Giddings (1952b). Sherd depth based on total reported depth of cultural features in adjacent houses (VanStone, 1955). Depth not reported for this house feature. Estimated sherd depth based on total reported depth of cultural features in the feature from which the sherd was collected ( Giddings, 1952b). Estimated sherd depth based on total reported depth of cultural features in the feature from which the sherd was collected ( Giddings, 1952b). Estimated sherd depth based on total reported depth of cultural features in the feature from which the sherd was collected ( Giddings, 1952b). Sherd depth based on total reported depth of cultural features in the feature from which the sherd was collected. Estimated sherd depth based on total reported depth of cultural features in the feature from which the sherd was collected ( Giddings, 1952b). Estimated sherd depth based on total reported depth of cultural features in the feature from which the sherd was collected ( Giddings, 1952b). Estimated sherd depth based on observed total depth of feature during summer 2010 site visit, and on simple stratigraphic drawings in Giddings (1952b). Estimated sherd depth based on observed total depth of feature during summer 2010 site visit, and on simple stratigraphic drawings in Giddings (1952b). Estimated sherd depth based on observed total depth of feature during summer 2010 site visit, and on simple stratigraphic drawings in Giddings (1952b). Estimated sherd depth based on observed total depth of feature during (continued on next page)

7

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Journal of Archaeological Science 112 (2019) 105030

Table 3 (continued ) Sample

Site

Accession

Sherd No.

Pottery Decorative Type

Feature

Cultural Affiliation

Site Area (m2) Estimate

Estimated Sherd Depth (m)

Site Sediment Texture

UW2348

Kotzebue

UA67-82

156

Plain

House 3 (VanStone)

Kotzebue

Unknown

0–.91 m

Sand, gravel, soil development in cultural layers

UW2349

Cloud Lake

UA75-51

1080

Plain

n/a

Late Thule

875

0–.25 m

ark brown rooty soil

2016 for additional details of survey design). In some cases, we could not link the previously reported features to specific features identified on the ground because site conditions have changed considerably in the intervening years. To collect associated sediment samples we excavated 30 cm diameter shovel probe in non-cultural deposits within the site boundaries and adjacent to (within 5 m) of relocated features where possible; sediment samples were collected from the maximum possible depth of the original ceramic sherd (see Table 4 for details). If we did not relocate a specific excavated feature, we collected a sediment sample from non-cultural deposits in the vicinity of the excavated feature as identified to the best of our abilities while in the field using available information. We did not seek permission to sample in cultural deposits for several reasons. First, the cultural deposits were entirely destroyed by prior excavation in the majority of cases; typically, Giddings exca­ vated multiple houses completely, leaving nothing cultural in the proximity of the original house excavation. In addition, land ownership in this region is complex, involving multiple federal and private parties; it was simply not in the scope of the current project to work through the permissions process. While the sediment sampling locations are not ideal, they are the best approximation available at this time. Further­ more, in all cases, the local natural stratigraphy is quite simple, e.g.

Sediment Sample No.

Ahteut

10GEOXH090509A Geo1A

56cmBS

Ahteut

10GEOXH090315A Geo1A

45cmBS

Ambler Island Black River

10GEOXH083111A Geo3A 10GEOXH082910A Geo4A 10GEOXH081813A Geo5A 10GEOXH090614A Geo1A 10GEOXH081609A Geo1A 10GEOXH081609A Geo2A 10GEOXH090208A Geo2A

37cmBS

UW2340, 2341,2342, 2343 UW2340, 2341,2342, 2343 UW2338, 2339

50cmBS

UW2347

20cmBS

UW2349

55cmBS 30cmBS

UW2336, 2344, 2345 UW2337, 2348

60cmBS

UW2337, 2348

60cmBS

UW2346

Cloud Lake Villagea Ekseavik Kotzebue Kotzebue Onion Portage

Associated Sediment Depth Below Surface (BS)

summer 2010 site visit, and on simple stratigraphic drawings in Giddings (1952b). Estimated sherd depth based on total reported depth of cultural features in the feature from which the sherd was collected ( Giddings, 1952b) Estimated sherd depth based on total reported depth of cultural features in the feature from which the sherd was collected ( Giddings, 1952b)

layers of sandy loam with little variation even in color; where reported, the original cultural stratigraphy is also very simple (e.g. sandy loam). In general, the University of Washington luminescence lab experience in­ dicates that if the stratigraphy is not overly complex, sediment samples from near where the ceramic sample was excavated are not a bad proxy for determining environmental dose rate. We further consider how these various constraints and limitations in our research design may factor into the resulting luminescence ages and their meaning in relationship to regional chronology in our results and discussion section 5. 4.2. Sample preparation Luminescence ages are obtained by dividing the equivalent dose (De), which is a laboratory estimate of the accumulated dose through time, by the dose rate, which is the rate at which ionizing dose is delivered to the sample. De was determined on fine-grained material using both thermoluminescence (TL) and a combined optically stimu­ lated luminescence (OSL) and infrared stimulated luminescence (IRSL). Both methods were employed to give two attempts at estimating the equivalent dose. The laboratory’s experience is that TL and OSL/IRSL do not always yield the same age and their differences can be informative about particular problems with the sample and whether reliable dates can be obtained (Feathers, 2009). For example, TL and OSL/IRSL behave differently in terms of ease of resetting and the effect of anomalous fading. Fine-grained polymineral material was obtained for luminescence measurements. Samples were prepared following standard lab proced­ ure (see Feathers, 2009). The sherd was broken to expose a fresh profile. Material was drilled from the center of the cross-section, more than 2 mm from either surface, using a tungsten carbide drill tip. The material retrieved was disaggregated gently by an agate mortar and pestle, treated with HCl, and then settled in acetone for 2 and 20 min to sepa­ rate the 1–8 μm fraction. This was settled onto a maximum of 72 stainless steel discs. Detailed procedures for De determination are given in Supplement 4. Single-aliquot TL methods are not well-developed, so a multi-aliquot method, called the slide method, which addresses sensitivity change during the course of measurement, was employed. Single-aliquot methods for OSL and IRSL, on the other hand, are well developed and we applied a version of the widely used single-aliquot regenerative (SAR) protocol (Murray and Wintle, 2000). This measures the natural signal and the signal from a series of laboratory doses, using a small test dose to correct for sensitivity changes. Our application used the so-called “double SAR”, where each measure of the luminescence signal consisted of first an exposure to infrared light (IRSL) and then an exposure to blue light (OSL) (Banerjee et al., 2001). The IRSL signal stems mainly from feldspars which are prone to anomalous fading (an athermal loss of

Table 4 Associated sediment contextual information. Site

Comments

Sherd No.

a Could not access site so used sample from nearest accessible site, Salix Bay (BEN-106).

8

S.L. Anderson and J.K. Feathers

Journal of Archaeological Science 112 (2019) 105030

signal through time). If the IRSL exposure removes most of the feldspar signal, then the subsequent OSL signal, mainly from quartz, will not fade much. This is not always the case, however, because blue light stimu­ lates luminescence in feldspars as well (Roberts, 2007). However, heat (when the ceramic was fired) often increases the sensitivity of quartz but decreases it for feldspars, increasing the chance that the OSL signal will derive mainly from quartz. This will be more often the case for ceramics than for unheated sediments. Fine-grained materials, which are subject to the effect of alpha irradiation, require a determination of alpha effi­ ciency, because alphas are less efficient at producing luminescence than betas or gammas. This provides another way to gauge how much the OSL signal is dominated by quartz. We use the b-value system (Bowman and Huntley, 1984) for this, which compares the slopes of dose response curves (plotting laboratory dose versus subsequent luminescence) created by either alpha or beta irradiation. The b-value is known to differ for quartz and feldspars. If the OSL produces a b-value in the range of quartz, it is much less likely to have suffered from anomalous fading. Dose rate was measured using alpha counting, beta counting and flame photometry, as outlined in Supplement 4. This was done on crushed samples, which in effect homogenized the samples to eliminate any heterogeneity in dose rate, which might be caused by large temper pieces typical in much Arctic pottery. Because the fine grains used to measure luminescence were derived from a broad section of the sample, an average dose rate over the ceramic should provide the best dose rate estimate. A major concern in dose rate estimation in these samples is the uncertainty in the external dose rate because sediment samples imme­ diately adjacent to the ceramics, which were excavated years ago, were not available. Instead, a sediment sample from the site as near as possible to the location of the ceramic was obtained. Another advantage of using fine-grain materials for dating is that the fine-grains are affected by alpha irradiation. The dose rate is thus composed of alpha and beta irradiation (both of which derive from the ceramic itself), and gamma irradiation (from the sediment), as well as cosmic radiation (which is not measured but calculated). Typically, the gamma irradiation may make up only about 25% of the total dose rate. With coarse-grained material, on the other hand, the dose rate is composed mainly of betas and gammas (plus cosmic), and the gamma irradiation may make up 50% of the total dose rate. Thus the gamma dose from the sediment is less important in fine-grain than coarse-grain materials, and higher uncer­ tainty can be tolerated (See Janz et al., 2015 for an example of dating ceramics from museum collections where no measurement of external dose rate is possible.). For moisture content, which affects the dose rate,

we estimated it as 80% of saturated values for the ceramics and 10 � 5% for the sediments. 5. Results and discussion 5.1. Dose rate results Table 5 gives the radioactivity of the samples while Table 6 gives the dose rates. Radioactivity varied widely for both the ceramics and the sediments. The beta dose rates as calculated either from alpha counting/ flame photometry or from beta counting were in statistical agreement for all but two samples. The reason for these two discrepancies is un­ certain, but the beta counting results, as a more direct measure, were used in age calculation for both. The overall agreement in the beta dose rate suggests that disequilibrium, at least at the top of the U decay chain involving potential soluble U, is probably not an issue. The use of direct measures like alpha counting and beta counting, which measure activity and not individual concentrations of radionuclides, provides some pro­ tection against movement of radium or radon as long as that movement was fairly constant through time. Because the sediment samples were not directly associated with the ceramics, there is some uncertainty in the gamma dose rate. This will have more of an effect for the two samples from Ambler Island (UW2338 and UW2339), UW2342 from Ahteut, and UW2349 from Cloud Lake Village, where low ceramic radioactivity means the gamma dose from the sediments contributed more than 45% of the total dose rate. For all others, the external dose rate was less than 26% for TL or 37% for OSL of the total (See Table 6 for values for each samples.). As detailed below, UW2339 has other problems as well, so the age is not reliable. For the other three with relatively high gamma dose rates, the derived ages agree with other information. To give an idea of the effect of uncertainty in the external dose, the OSL age for UW2347 was recalculated assuming an increase or decrease of the radioactivity by a third. The gamma dose rate made up 32% of the OSL dose rate for this sample, on the high end for these samples. The resulting ages are 8.84 � 1.03 ka for the estimated amount, 9,81 � 1.48 ka for a third higher than the estimate and 8.33 � 1.71 ka for a third lower than the estimate. These are all within error terms. The dose rates for OSL (Table 6) are less than those for TL because of lower alpha efficiency.

Table 5 Luminescence sample radioactivity. Sample

238

UW2336 UW2337 UW2338 UW2339 UW2340 UW2341 UW2342 UW2343 UW2344 UW2345 UW2346 UW2347 UW2348 UW2349 Kotzebue sediment (10GEOXH081609A Geo 2A) Elseavik sediment (10GEOXH090614A Geo1A) Ahteut sediment 1 (10GEOXH090509A Geo1A) Ahteut sediment 2 (10GEOXH090315A Geo1A) Onion Portage sediment (10GEOXH090208A Geo2A) Black River sediment (10GEOXH082910A Geo4A) Cloud Lake sediment (10GEOXH081813A Geo5A)

2.52 � 0.17 6.08 � 0.55 0.33 � 0.03 0.37 � 0.03 2.50 � 0.20 1.48 � 0.16 0.87 � 0.10 0.95 � 0.18 5.78 � 0.39 2.97 � 0.20 4.92 � 0.36 1.70 � 0.15 1.43 � 0.78 3.04 � 0.23 0.89 � 0.08 1.70 � 0.15 0.92 � 0.19 2.48 � 0.23 2.35 � 0.22 5.06 � 0.31 2.24 � 0.19

U (ppm)

233

K (%)

5.11 � 0.91 40.13 � 3.22 0.11 � 0.12 0.01 � 0.01 10.63 � 1.25 10.31 � 1.31 0.39 � 0.22 15.79 � 1.58 15.95 � 1.83 7.33 � 1.03 17.60 � 1.90 7.81 � 1.02 4.65 � 0.12 10.28 � 1.36 2.17 � 0.55 6.99 � 1.06 16.93 � 1.73 15.78 � 1.57 12.93 � 1.51 8.45 � 1.30 9.11 � 1.25

1.97 � 0.10 3.74 � 0.14 0.19 � 0.01 0.14 � 0.01 1.82 � 0.07 1.24 � 0.05 0.17 � 0.01 2.17 � 0.10 1.46 � 0.05 0.69 � 0.03 1.66 � 0.07 2.15 � 0.08 1.64 � 0.08 1.02 � 0.05 0.32 � 0.01 0.92 � 0.04 0.89 � 0.04 1.88 � 0.09 1.02 � 0.05 2.07 � 0.09 8.03 � 0.33

Th (ppm)

9

Beta Dose Rate (Gy/ka) β-counting

α-counting/flame photometry

1.87 � 0.17 4.22 � 0.35 0.28 � 0.03 0.24 � 0.07 2.11 � 0.20 1.36 � 0.12 0.30 � 0.03 2.35 � 0.20 2.20 � 0.20 1.13 � 0.10 2.26 � 0.20 2.00 � 0.19 1.73 � 0.14 1.43 � 0.15

2.09 � 0.09 4.98 � 0.16 0.20 � 0.01 0.16 � 0.01 2.12 � 0.07 1.49 � 0.06 0.28 � 0.03 2.31 � 0.09 2.45 � 0.09 1.19 � 0.05 2.53 � 0.09 2.19 � 0.07 1.65 � 0.13 1.54 � 0.07

S.L. Anderson and J.K. Feathers

Journal of Archaeological Science 112 (2019) 105030

Table 6 Luminescence dose rates. Sample

Method

UW2336

TL OSL TL OSL TL OSL TL OSL TL OSL TL OSL TL OSL TL OSL TL OSL TL OSL TL OSL TL OSL TL OSL TL OSL

UW2337 UW2338 UW2339 UW2340 UW2341 UW2342 UW2343 UW2344 UW2345 UW2346 UW2347 UW2348 UW2349 a

Dose Rate (Gy/ka)

% gamma dose rate of total

Alpha

Beta

Gamma

Cosmic

Total

1.20 � 0.22 0.57 � 0.15 5.68 � 1.38 1.39 � 0.09 0.12 � 0.03 0.02 � 0.01 0.27 � 0.11 0.03 � 0.01 1.96 � 0.24 1.35 � 0.44 1.76 � 0.39 0.43 � 0.12 0.51 � 0.16 0.15 � 0.03 1.40 � 0.25 0.39 � 0.06 2.80 � 0.37 0.71 � 0.13 1.86 � 2.35 0.37 � 0.14 3.52 � 0.63 2.29 � 0.19 2.06 � 0.72 0.71 � 0.09 1.20 � 0.34 0.19 � 0.04 2.22 � 0.49a 0.65 � 0.06

1.70 � 0.11 1.70 � 0.11 3.83 � 0.33 3.83 � 0.33 0.24 � 0.03 0.24 � 0.03 0.21 � 0.06 0.21 � 0.06 1.89 � 0.08 1.89 � 0.08 1.32 � 0.06 1.32 � 0.06 0.25 � 0.02 0.25 � 0.02 1.97 � 0.11 1.97 � 0.11 2.07 � 0.11 2.07 � 0.11 0.97 � 0.09 0.97 � 0.09 2.12 � 0.12 2.12 � 0.12 1.93 � 0.09 1.93 � 0.09 1.43 � 0.12 1.43 � 0.12 1.37 � 0.07 1.37 � 0.07

0.72 � 0.06 0.72 � 0.06 0.68 � 0.06 0.68 � 0.06 1.27 � 0.10 1.27 � 0.10 1.29 � 0.10 1.29 � 0.10 1.18 � 0.08 1.18 � 0.08 1.15 � 0.08 1.15 � 0.08 1.04 � 0.07 1.04 � 0.07 1.24 � 0.08 1.24 � 0.08 0.83 � 0.06 0.83 � 0.06 0.71 � 0.06 0.71 � 0.06 1.14 � 0.09 1.14 � 0.09 1.31 � 0.09 1.31 � 0.09 0.34 � 0.04 0.34 � 0.04 2.05 � 0.67 2.05 � 0.67

0.17 � 0.04 0.17 � 0.04 0.17 � 0.04 0.17 � 0.04 0.21 � 0.04 0.21 � 0.04 0.21 � 0.04 0.21 � 0.04 0.19 � 0.04 0.19 � 0.04 0.17 � 0.04 0.17 � 0.04 0.17 � 0.03 0.17 � 0.03 0.19 � 0.04 0.19 � 0.04 0.17 � 0.04 0.17 � 0.04 0.17 � 0.04 0.17 � 0.04 0.17 � 0.04 0.17 � 0.04 0.20 � 0.04 0.20 � 0.04 0.20 � 0.04 0.20 � 0.04 0.24 � 0.05 0.24 � 0.05

3.80 � 0.25 3.16 � 0.20 10.4 � 1.42 6.07 � 0.35 1.85 � 0.12 1.75 � 0.11 1.99 � 0.17 1.75 � 0.13 5.22 � 0.27 4.61 � 0.45 4.41 � 0.40 3.08 � 0.16 1.97 � 0.18 1.61 � 0.09 4.81 � 0.28 3.79 � 0.15 5.87 � 0.39 3.79 � 0.19 3.71 � 2.35 2.21 � 0.18 6.95 � 0.65 5.73 � 0.25 5.51 � 0.74 4.16 � 0.16 3.17 � 0.37 2.16 � 0.14 5.87 � 0.83 4.31 � 0.67

19 23 7 11 68 72 65 74 23 26 26 37 52 65 26 33 14 22 19 32 16 20 24 32 11 16 35 48

Value only approximate because b-value not directly measured but based on average of other ceramics.

5.2. Equivalent dose

was not reset at time of firing. On one of them, UW2338, the OSL pro­ vided a much younger age suggesting that at least that signal was reset. The other two, both with relatively narrow plateaus, also had high OSL signals, and it could be argued that the signals were not completely reset for these two. Most samples had high sensitivity change after heating (see 1st/2nd ratio in Table 7). Anomalous fading was detected on all samples where it was measured. On many of these the precision in g-value (fading rate) was poor (Table 7). A few samples had limited amount of 1–8 μm material, so only a few aliquots could be measured for TL (all the samples with no fading test). UW2349 had particularly limited material (only two aliquots available for TL), and only a very rough estimate of equivalent dose could be made. Two samples, UW2337 and UW2345, showed a negative intercept on the regeneration curve, so no reliable use of the slide method could be done. The equivalent dose was determined by additive dose, so the results should be accepted with caution. Despite this uncertainty, the TL age for UW2337 agreed with that from OSL. The natural TL signal and growth curve are shown for UW2340 in Supplement 5 Figs. S1 and S2. This sample showed somewhat better behavior than some of the others. OSL/IRSL was measured on from three to seven aliquots per sample, depending on sample size. There was no measurable IRSL signal on any of the samples, except weak signals on UW2337 and UW2345. The OSL signals were not particularly strong either. Samples UW2337, UW2340, UW2343, UW2344, and UW2348, were the only samples with strong OSL signals; other samples had signals barely above background. Sup­ plement 5, Figs. S3 and S4 show OSL decay curves and corresponding growth curves for UW2337 and UW2341. Although the signal on all was dominated by quartz (as inferred from lack of IRSL signal), some samples did not appear to have a fast-bleaching component, as evidence from a high equivalent dose value that may not have been zeroed at the time of manufacture. Dose recovery experiments, tests of procedures where an attempt is made to recover a known dose, were satisfactory for all but UW2347 and UW2349, where the dose was underestimated but the error was high on both samples. Equivalent dose values are given in Table 8. Table 8 also includes

Equivalent dose was determined by TL, IRSL and OSL, as mentioned. The samples did not have ideal luminescence characteristics. Scatter was high on all but five of them. TL plateaus, which measures, in part, the thermal stability of the signal over time by plotting De against temperature, varied (Table 7), some with fairly narrow plateaus, others more broad. This plateau test allows some evaluation as to whether the ceramic was sufficiently fired for resetting in antiquity (Aitken, 1985). An insufficiently fired ceramic will likely have no plateau or one at fairly high temperatures. From the plateaus, all of the samples appear to have been adequately fired. But three samples, UW2338, UW2339 and UW2345, produced unreasonably old ages that might suggest a geologic component to the signal, i.e. it Table 7 Thermoluminescence parameters. Sample

Plateau (� C)

1st/2nd ratioa

Fit

g-valueb

UW2336 UW2337 UW2338 UW2339 UW2340 UW2341 UW2342 UW2343 UW2344 UW2345 UW2346 UW2347 UW2348 UW2349

250–350 250–330 270–350 300–350 250–330 260–310 310–330 260–340 250–290 250–300 250–340 250–370 290–340 250–320

0.74 � 0.09 1.0 0.46 � 0.07 0.33 � 0.11 1.0 1.46 � 0.19

Linear Linear Linear Linear Linear Linear Linear Linear Quadratic Linear Linear Linear Linear Linear

1.14 � 2.46 2.91 � 4.83 13.70 � 9.80 4.03 � 5.10 4.84 � 1.11 0.65 � 3.07 5.38 � 2.89 11.16 � 4.91 8.55 � 5.08 No test No test No test 10.99 � 15.18 No test

0.69 � 0.13 1.0 1.0 0.39 � 0.05 0.30 � 0.09 0.36 � 0.08 0.31 � 0.09

a

Refers to slope ratio between the first and second glow growth curves. A glow refers to luminescence as a function of temperature; a second glow comes after heating to 450 � C. b g-value is the fading rate expressed as % per decade, where a decade is a power of 10. 10

S.L. Anderson and J.K. Feathers

Journal of Archaeological Science 112 (2019) 105030

Table 8 Equivalent Dose. The number of aliquots for OSL are given in parenthesis. Sample

TL UW2336 UW2337 UW2338 UW2339 UW2340 UW2341 UW2342 UW2343 UW2344 UW2345 UW2346 UW2347 UW2348 UW2349 a

Over-dispersion (%)

b-value (Gy μm2)

OSL

OSL

TL

8.68 � 2.10 (1) 3.52 � 0.15 (7) 1.86 � 0.53 (5) 10.28 � 2.30 (5) 52.4 � 7.43 (5) 4.70 � 0.56 (3) 6.06 � 0.94 (3) 31.56 � 5.05 (3) 20.91 � 1.60 (5) 8.14 � 1.76 (1) 2.59 � 0.32 (6) 4.68 � 0.64 (3) 54.55 � 9.59 (1) 1.62 � 0.23 (3)

0 8.4 � 3.9 0 46.6 � 16.9 26.1 � 12.1 8.7 � 20.0 0 0 0 0 32.7 � 17.2 0 0 0

2.23 � 0.35 2.14 � 0.48 2.44 � 0.52 4.94 � 1.73 2.38 � 0.25 2.71 � 0.54 3.40 � 0.99 1.83 � 0.29 1.93 � 0.22 2.58 � 3.04 2.54 � 0.41 3.56 � 1.16 3.03 � 0.78 2.50 � 0.5a

Equivalent dose (Gy) 3.68 � 0.56 3.03 � 0.50 9.50 � 1.14 9.41 � 4.84 3.32 � 0.14 1.18 � 0.40 1.65 � 0.47 6.60 � 1.18 5.42 � 0.37 14.39 � 3.16 2.18 � 0.32 3.99 � 1.74 4.66 � 1.01 6.05 � 0.52a

IRSL 2.31 � 0.23

9.58 � 2.88

IRSL 1.24 � 0.31

1.39 � 0.22

OSL 1.06 � 0.25 0.52 � 0.03 0.48 � 0.11 0.49 � 0.08 1.64 � 0.49 0.66 � 0.17 0.99 � 0.20 0.51 � 0.07 0.49 � 0.08 0.51 � 0.18 1.66 � 0.10 1.23 � 0.13 0.74 � 0.05

Approximate values, based on small number of aliquots.

other OSL variables; specifically, the number of aliquots on which the equivalent dose is based and the over-dispersion (spread in values among aliquots that cannot be accounted for by differential precision). For some samples only a few aliquots produced reliable signals. For the five samples with over-dispersion more than zero, radial graphs were produced to show the distribution. These are displayed in supplemental material (Supplement 5), except for UW2337 which is shown in Fig. 4. Table 8 also lists b-values, which as mentioned are measures of the relatively lower efficiency of alpha irradiation in producing lumines­ cence. The OSL b-values of around 0.3–0.8 are typical for quartz, and for samples with these values, the OSL signal is not likely to fade. The higher b-values could mean other minerals, such as feldspars, are involved, and could be affected by fading, although no samples with high b-values had a measurable IRSL signal.

5.3. Age estimates Table 9 gives both the TL and the OSL ages, in ka, for each sample. The age considered the best estimate, as discussed next, is given in bold and is translated into a calendar date. In the cases where the OSL and TL ages are in agreement, the calendar date represents a weighted average. Of the three samples where the ages are in agreement, only UW2347 is considered reliable. The other two, UW2339 and UW2345, yield ages which are unreasonably old considering the archaeology. We do not know the reason for this. It is possible these samples were insufficiently heated in antiquity to zero the luminescence signal, although both had a plateau, albeit relatively narrow. Perhaps they were not fired at all, and the age represents the geologic age of the materials, in this case from mid-Holocene deposits. An alternative is that the signals were domi­ nated by hard-to-bleach signals, even with heating, but for TL, at least, all samples displayed the easy-to-bleach 325 � C peak (see Supplement 5 Fig. S1). One other sample, UW2338, produced an old TL age, but in this case, the OSL signal produced a reasonable age. Six samples (UW2336, UW2340, UW2342, UW2343, UW2344, and UW2348) produced an unreasonably old OSL age, sometimes very old, such as for UW2348. In these cases, the TL produced reasonable ages. This is harder to explain by poor firing, because the TL signal appeared to have been zeroed. Through many years of measuring OSL on ce­ ramics, the University of Washington lab has documented in several cases anomalously old OSL ages. We have attributed this to a weak fast (easy to bleach) component and dominance by a slow (hard to bleach) component. Indeed, the decay curves for some of these samples show a slower rate of decay, as can be seen in Fig. 5, which compares the decay curves for aliquots from UW2340, which has an anomalously old OSL age, and from UW2337, which has a reasonable OSL age. Another reason might be a large sensitivity change after the natural signal was measured but which was not able to be corrected by the SAR protocol (see sup­ plemental material for the SAR protocol: Supplement 4). In any case, for these samples the TL signal provides the best estimate. All were either corrected for anomalous fading or were assumed not to fade signifi­ cantly because the corrected age did not differ statistically from the uncorrected age. The latter could partly be an effect of high scatter in the fading data. On two other samples, UW2341 and UW2349, the OSL age was also older than the TL age, but the OSL age was not unreasonably old. In the case of UW2341, context does not help in deciding which might be more correct, because the TL age is younger than all others from the Ahteut site, and the OSL age is older. We think the best that can be said about this sample at this time is that it dates somewhere in the same range as the other Ahteut samples. This sample also had uncertain dose rate due to relatively low internal radioactivity and uncertain external radioac­ tivity. UW2349 is the only date from Cloud Lake Village, but in this case

Fig. 4. Radial graph for OSL De values for UW2337. A radial graph plots pre­ cision against De. The values of De are normalized by the number of standard errors a value is away from some reference, in this case the average as deter­ mined by the Central Age Model (Galbraith and Roberts, 2012). The shaded area encompasses all points within two standard errors of the reference. A line drawn from the origin through any point will intersect the axis on the right at the measured value. 11

S.L. Anderson and J.K. Feathers

Journal of Archaeological Science 112 (2019) 105030

Table 9 Results of luminescence dating. Sample

Site

Accession

Sherd No.

Pottery Decorative Type

Feature

TL Age (ka)

OSL Age (ka)

Basis for age

Date (years BC/ AD)

% error

UW2340 UW2341 UW2342 UW2343 UW2338

Ahteut Ahteut Ahteut Ahteut Ambler Island Ambler Island Black River Cloud Lake Ekseavik Ekseavik Ekseavik Kotzebue Kotzebue

1–1941 1–1941 1–1941 1–1941 1–1941

2348 2119B 2168 2086 2483

Plain Plain Curvilinear Stamp Plain Plain

House House House House House

0.78 � 0.07a 0.27 � 0.10a 1.05 � 0.35a 1.37 � 0.26b 5.14 � 0.72b

11.4 � 1.99 1.53 � 0.21 3.77 � 0.63 8.33 � 1.40 1.06 � 0.32

TL TL TL TL OSL

AD AD AD AD AD

9.4 36.8 33.5 19.1 29.6

1–1941

2480

Plain

House 7

5.90 � 3.62a

5.88 � 1.40

TL/OSL

BC 3880 � 1300

22.1

1–1941 UA75-51 1–1941 1–1947 1–1941 1–1947 UA67-82

2530 1080 141 1854 308 2115A 156

Plain Plain Plain Plain Striated Plain Plain

0.72 � 0.33 1.03 � 0.17 1.01 � 0.20a 0.92 � 0.09b 3.88 � 2.61 0.32 � 0.09a 1.47 � 0.36b

1.13 � 0.16 0.38 � 0.08 2.74 � 0.69 5.52 � 0.53 3.68 � 0.86 0.58 � 0.05 25.2 � 4.79

TL/OSL OSL TL TL TL/OSL OSL TL

AD 880 � 160 AD 1630 � 80 AD 1000 � 200 AD 1090 � 90 BC 1690 � 810 AD 1430 � 50 AD 540 � 360

13.9 21.2 19.7 10.1 22 7.8 24.8

Onion Portage

1-1941 (28)

3635

Plain

House 3 n/a House 5S House 10 House 4 House 10 House 3 (VanStone) House 1

0.31 � 0.06

0.45 � 0.06

OSL

AD 1560 � 60

13.5

UW2339 UW2347 UW2349 UW2336 UW2344 UW2345 UW2337 UW2348 UW2346 a b

2S 10S 12S 6AS 3

1230 � 70 1740 � 100 960 � 350 640 � 260 950 � 310

Corrected for anomalous fading. Fading not significant, but errors on fading correction high.

relationship to other dated materials, and by comparing the lumines­ cence ages to other chronological information from the study sites. As discussed in previous sections, contextual information for the ceramic samples is limited. We are not sure whether the samples came from within each house feature, floor or fill. The same is true of the materials radiocarbon dated by Shirar (2011) from the same sites and collections. Giddings’ tree ring dates have the advantage of being done on structural timbers, but the overall sequence of house construction is not known and there is the potential for old wood issues with both tree ring and radiocarbon dates. We chose to date ceramics from previously undated houses in order to expand the chronological information for the study sites. If we had chosen instead to date ceramics from houses already dated via tree rings or radiocarbon, we would still have the problem of association between the age of the ceramics (luminescence dates time of ceramic firing) and the other dates (dating death of tree or other organism), the unknown occupation sequence for the houses, and the potential confounding factors of artifact/wood curation, re-use, and recycling over the life cycle of the objects and the occupation features. The best that can be done in the case of old collections with limited contextual information such as these is to date a variety of materials, preferably using different methods, and to compare the resulting ages to each other and other chronological information, which we do below. The post AD 1200 luminescence ages from Onion Portage and Cloud Lake Village are consistent with our expectations for these sites based on prior dating. The luminescence date for Onion Portage is younger than radiocarbon ages for the site by several hundred years, but is within a reasonable range based on limited available information about the late Holocene component of the Onion Portage site (Anderson, 1998) (Fig. 6). Many late Holocene sites were occupied into the contact era (e. g. Giddings and Anderson, 1986) and some are still used today for sea­ sonal subsistence activities as is evident from the numerous private Native land claims at the study sites along the Kobuk River and across the region. The Cloud Lake Village luminescence date is within the ex­ pected range for the site as established through prior relative dating of artifacts (Adams, 1977; Powers et al., 1982) (Fig. 6). Both of these sites could benefit from additional dating. The Onion Portage site in partic­ ular is known to be multi-component (Anderson, 1988); more dating is needed to further establish the late Holocene chronology at the site. The luminescence dates between AD 700 and 1000 do not align as closely with other chronological information as the Onion Portage and Cloud Lake Village ages. The Ahteut luminescence dates are older than the tree ring dates from the site (particularly UW2343 AD 640 � 260), but two of the luminescence ages (UW2340 and 2342) do overlap with

Fig. 5. OSL decay curves showing different decay rates.

the TL age is only a very rough estimate, because only two aliquots were available to make the assessment. The OSL age is considered much more reliable. The OSL age was older than TL for UW2337 and UW2346, but in these cases the fading correction for TL was inadequate, making the OSL age more reliable. For UW2346, the two lowest values were dis­ carded as outliers. 5.4. Comparison of luminescence ages to other contextual and chronological information In sections 5.1-5.3, we discussed the reliability of ages resulting from luminescence dating through a consideration of various luminescence measures. We considered how the constraints of the project, i.e. lack of associated sediments and resulting dose rate calculations, factored into the reliability of resulting ages. Overall, the samples did not have the best luminescence characteristics. The lack of directly associated sedi­ ments, a problem inherent in using many museum collections, likely introduced some error into radioactivity measurements. We find that two of the resulting ages, UW2339 and UW2345, can be rejected because of produced ages that seem unreasonably old given the archaeology, perhaps because of insufficient firing (Table 9). The rest of the dates fall into two groups, those that date between about AD 700–1000 and those younger than AD 1200 from Onion Portage and Cloud Lake Village. In the following paragraphs, we further consider the reliability of these ages by considering the context of the samples in 12

S.L. Anderson and J.K. Feathers

Journal of Archaeological Science 112 (2019) 105030

Years B.C. / A.D. 500

Old Kotzebue Tree Ring Age Kotzebue (TU 21) D-AMS 009423 Kotzebue (Feature 45) D-AMS 009765 Kotzebue (Feature 45) D-AMS 009422

0

500

1000

1500

2000

Tree Ring Ages* Luminescence Ages Radiocarbon Ages*

Kotzebue (Feature 14) D-AMS 009763 Kotzebue (Locality B) Beta-257766 Kotzebue (n/a) D-AMS 009424 Kotzebue (Feature 81) D-AMS 009764 Kotzebue (TU 15) D-AMS 009414 Kotzebue (Feature 14) D-AMS 009415 Kotzebue (Feature 60) D-AMS 009768 Kotzebue (Feature 70) D-AMS 009767 Kotzebue (TU 24) D-AMS 009754 Kotzebue H10 (Plain) UW2337 Kotzebue (Feature 104) D-AMS 009766 Kotzebue (Feature 63) D-AMS 009769 Kotzebue (TU 15) D-AMS 009755 Kotzebue (Feature 14) D-AMS 009762 Kotzebue (Locality A) Beta-257762 Kotzebue (TU 43) D-AMS 009416 Kotzebue (TU 22) D-AMS 009770 Kotzebue (Locality B) Beta-257767

Dated Samples

Kotzebue (Locality A) Beta-257763 Kotzebue (Locality A) Beta-257765 Kotzebue H3 (V) (Plain) UW2348 Intermediate Kotzebue Tree Ring Age Black River H3 (Plain) UW2347 Ambler Island Tree Ring Age Ambler Island House 11 Cams-141643 Ambler Island House 2 Cams-141642 Ambler Island House 2 Cams-141645 Ambler Island House 11 Cams-141644 Ambler Island H3 (Plain) UW2338 Onion Portage H1 (Plain) UW2346 Onion Portage Band 1 P-1112 Onion Portage Band 1 P-593A Onion Portage Band 1 P-1064 Ekseavik Tree Ring Age Ekseavik House 11 Cams-141646 Ekseavik House 11 Cams-141648 Ekseavik House 1 Cams-141647 Ekseavik House 11 Cams-141649 Ekseavik H5S (Plain) UW2344 Ekseavik H5S (Plain) UW2336 Cloud Lake (Plain) UW2349 Ahteut H10S (Plain) UW2341 Ahteut Tree Ring Age Ahteut House 10 Cams-141640 Ahteut House 10 Cams-141641 Ahteut H2S (Plain) UW2340 Ahteut H12S (Curvilinear) UW2342 Ahteut H6AS (Plain) UW2343 * Radiocarbon ages were calibrated in Oxcal 4.3 (Ramsey, 2009) with IntCal 13 (Reimer et al., 2013). Tree ring age ranges are as established by prior tree ring analysis (Giddings,1952b; Graumlich and King, 1997; VanStone 1955).

Culture Historic Periods

EAW | LAW Thule Birnirk Ipiutak

Fig. 6. Figure 6. Comparison of new luminescence dates from Ahteut, Ambler Island, Black River, Cloud Lake Village, Ekseavik, Kotzebue, and Onion Portage (UW 2345 and 2339 excluded) with radiocarbon and tree ring ages from same sites. Box represents 1 sigma ranges and whiskers represent two sigma ranges. Note correspondence to cultural historical phases at bottom of figure (Figure by Johonna Shea).

13

S.L. Anderson and J.K. Feathers

Journal of Archaeological Science 112 (2019) 105030

the radiocarbon and tree ring ages (Fig. 6). UW2341 suggests that there may be a more recent occupation at Ahteut than identified by tree ring or radiocarbon dating (although see discussion in Section 5.1 for reli­ ability of luminescence date). Tree ring dating at Ekseavik indicated that this site was roughly contemporaneous with Ahteut (Giddings, 1952b) (Table 1). But, luminescence dating also yielded older ages at Ekseavik, in a similar range as the older luminescence dates from Ahteut (Fig. 6). The radiocarbon ages from Ekseavik fill the gap between the lumines­ cence and tree ring ages for the site, suggesting that there could have been more extensive occupation at the site than previously understood. Radiocarbon dating of Ahteut, Ekseavik, and other Kobuk-style arrow­ head and harpoon points from the Nukleet and Iyatayet sites on Norton Sound (Murray et al., 2003), yielded older dates than expected for the sites based on tree ring data alone (Table 10). Murray et al.’s (2003) dates are in accord with new radiocarbon (Shirar, 2011) and lumines­ cence ages from the Kobuk affiliation sites reported for the first time in this paper, further suggesting the potential for earlier occupation at Kobuk River sites than previously established. The luminescence dates for Ambler Island and Black River sites are difficult to interpret because contextual information about the site, e.g. size, sediments, etc., are particularly limited for these sites (see Gid­ dings, 1952b). In the absence of any dates, Giddings (1952b) assumed that Black River was contemporaneous with the Ambler Island site based on house forms and artifacts; he noted, however, that preservation alone suggested that Black River might be older than Ambler Island (Giddings, 1952b:121). The tree ring dates from Ambler Island led Giddings (1952b) to think that the site was occupied during the 18th century. Shirar’s (2011) radiocarbon dating of Ambler Island materials over lapped with the tree ring dates and also indicated that the occupation of Ambler Island was slightly older than originally thought, dating from AD 1440 to the modern era (510 cal BP to modern era). The luminescence dates for both Black River and Ambler Island are older than the tree ring and radiocarbon dates from Ambler Island, AD 950 � 310 (UW2338) and AD 880 � 160 (UW2347) (Fig. 6). The overlap between lumines­ cence ages at Black River and Ambler Island suggest that the sites were, indeed, occupied during the same time period as Giddings hypothesized, but that occupation began earlier than previously thought based on tree rings and radiocarbon dates. These sites could have Birnirk or early Thule components. Reconnaissance fieldwork at Ahteut, Ekseavik, Black River, Ambler Island, and Onion Portage (Anderson, 2011, 2016) indicates that the sites are all larger (i.e. consisting of more occupation features) than can be understood from the existing publication (Giddings, 1952b). It is also apparent from comparing field data to the collections that these sites were not fully reported by Giddings (1952b); there were additional ex­ cavations for which we have no collections. In summary, there is

considerable potential for previously undated components at these sites; our luminescence ages further suggest this possibility. Additional field work and dating is needed to further explore the extent of occupation at these sites. At the Kotzebue site complex, our luminescence ages are in accor­ dance with both radiocarbon and tree ring data (Fig. 6). Four dates (Beta 257765, Beta 257763, Beta 257767, and D-AMS 009770) date to be­ tween 1255 and 1090 cal BP (AD 695–864), overlapping with our older luminescence date (UW2348 AD 540 � 360). There is a short gap in the radiocarbon dataset for the site complex, from approximately AD 900–1250, and then a second series of radiocarbon dates that range from about AD 1250 to the modern era, overlapping with tree ring dates and our younger luminescence date for the site (UW2337 AD 1430 � 50). Artifacts recovered by recent investigations at the site (Odell et al., 2015; Shinabarger, 2014) also suggest that the site complex has an earlier Birnirk or Thule period component in addition to the late Thu­ le/Kotzebue period (ca. 550 cal BP to the modern era) component originally identified by Giddings (1952b) and VanStone (1955). Shina­ barger’s (2014:128) hypothesizes that the site may have an Ipiutak cultural (1750-1150 cal BP) component as well; there are no ceramics associated with the Ipiutak period, so our older luminescence date cannot be attributed to Ipiutak culture. However, Birnirk and Ipiutak peoples occupied northwest Alaska for the same time for at least 200 years so there is the potential for mixed assemblages dating to ca. 1350-1150 cal BP. Tree ring, luminescence, and radiocarbon data, along with artifact evidence, suggests that occupation of the Kotzebue site complex was likely more extensive than previously thought. Kotzebue may have been continuously, or near continuously, occupied as Van­ Stone proposed in 1955. Occupation of the site complex may have begun 550 or more years earlier than indicated by tree ring data alone. The luminescence ages suggest that the age of the Kotzebue site complex should be further investigated. Our results indicate that ceramic luminescence dating on relatively low fired hunter-gatherer ceramics from western Arctic sites can provide reasonable chronological information even if luminescence properties are not ideal. In the following section, we briefly consider the potential broader significance of the new dates, and argue that additional research is needed to further explore the issues raised by this research. 5.5. Potential broader significance of new dates The luminescence dates suggest that at least some of these sites were occupied earlier than previously established. Radiocarbon and lumi­ nescence dates at Kotzebue fall within the Birnirk period (ca. 1350750 cal BP). Luminescence ages at Ahteut, Ambler Island, and Ekseavik also fall into the Birnirk or Birnirk-Thule transitional period (ca. 950-

Table 10 Radiocarbon Dates on Kobuk and Kotzebue style Harpoon Points and Arrowheads from the Nukleet and Iyatayet Sites (Murray et al., 2003:100–101)a. Italicized samples have older dates than expected. Sample ID

Kobuk Affiliation

Wider Affiliation

Conventional Age

2 sigma AD

2 sigma cal BP

Artifact Type

Nukleet 2657 Nukleet 2651 Nukleet 2685 Nukleet 2543 Nukleet 2555 Nukleet 2573 Iyatayet IYH1

Ekseavik

Early Thule, Nuwuk (AD 900–1400)

480 � 40

1327–1476

624–475

Intermediate Kotzebue

Uncertain, similar to middle Birnirk Thule Type 4 Uncertain

530 � 40

1310–1445

640–506

860 � 40

1045–1260

906–690

Late Thule (AD 1400–1750)

380 � 40

1441–1635

510–315

Ekseavik

Late Thule (AD 1400-1750)

800 � 40

1166–1278

785–673

Ahteut

Late Birnirk through Late Thule (AD 800-900 to AD 1750) Late Birnirk through Late Thule (AD 800–900 to AD 1750)

860 � 40

1045–1260

906–690

580 � 40

1297–1422

653–529

Closed socket bladed raised design type 4 Closed socket self bladed plain type 1 Closed socked bladed split spur type 9 Square shoulder conical tang type 4 Square shoulder conical tang double barb type 3 No shoulder conical tang single barb type 12 No shoulder conical tang type 13

a

Local Norton Bay tradition, pre-Ahteut AD 1200–1250 or earlier Ekseavik

Old Style pre-Ahteut

Excluded Thule Type 2 IYE sample on marine ivory. 14

S.L. Anderson and J.K. Feathers

Journal of Archaeological Science 112 (2019) 105030

750 cal BP); radiocarbon ages at Ahteut and Onion Portage also indicate a possible transitional occupation at these sites. Shirar (2011) obtained radiocarbon dates for two sites on the Noatak River (Fig. 1), the Maiyumerak Creek and Lake Kaiyak sites. At least one house at Maiyumerak Creek was occupied between 850 and 650 cal BP (AD 1100–1300), indicating early Thule expansion into the interior of the region. Together, this evidence suggests the possibility of previously unidentified Birnirk or early Thule site components at Kotzebue and in the interior of the region; if this possibility is supported by further research it would mean that Thule people moved more rapidly into the interior of the region than previously understood. This expansion could have taken place soon after the initial Birnirk colonization of northern Alaska beginning around 1350 cal BP. There are relatively few known Birnirk settlements in northwest Alaska (Mason, 1998, 2009), and the possibility of Birnirk and early Thule components at Kotzebue and interior sites invites further investigation of these locales. Renewed research at these sites, and investigation of other interior sites that have only been minimally investigated (e.g. Giddings, 1952b: Appendix I) could provide new information about this period of significant cultural migration, interaction, and change. More broadly, this work and other recent dating efforts in the region illustrates what can be learned from expanding dated sample size and obtaining large suites of dates from sites (e.g. Anderson and Freeburg, 2013; Arundale, 1981; McGhee, 2000; Park, 2000; Shirar, 2011; Taylor, 1987). This research has significance beyond refining the chronology of colonization and migration into, and across, the North American Arctic. Our results indicate that luminescence dating ceramics from early pot­ tery sites in Alaska, those associated with Choris and Norton cultures, and associated cultures in northeast Asia should be explored in the future; these higher fired ceramics may be more suitable for lumines­ cence dating and they are often the only material other than lithics preserved at Choris and Norton sites (e.g. Giddings and Anderson, 1986). Direct dating of ceramics from this time period would signifi­ cantly inform our understanding of the earliest migrations into Alaska, shedding light on the long term specifics of cultural interaction and transmission across the Bering Strait during the Holocene. A chronology based, at least in part, on ceramic dating would help address questions about why people migrated into Alaska and why some but not all eastern Beringian technologies came with initial Holocene migrants. For example, pottery is not present in Alaska until approximately 2500 years ago but are in nearby Chukotka by about 5000 years ago (see Anderson et al., 2017 for discussion). A better chronology of mid-late Holocene population dynamics in the Russian Far East would allow us to evaluate hypothesized relationships between eastern Beringian social change, regional environmental and related resource shifts, and migration into Alaska (e.g. Mason, 1998; Tremayne and Winterhalder, 2017). Our work demonstrates the potential of dating relatively low-fired hunter-gatherer pottery, which is relatively rare but found around the world in early coastal hunter-gatherer cultures. Ceramic luminescence dates in these contexts could provide needed chronological information about early pottery traditions, and the possible link between those early pottery traditions and the development of aquatic adaptations (e.g. Anderson et al., 2017; Craig et al., 2013; Lucquin et al., 2016).

and can complement other dating methods that are more widely accepted. Our secondary goal was to refine the chronology for the study sites in ~ upiat and Inuit the interest of informing research on the spread of In people across northwest Alaska and into the North American Arctic. Luminescence dates suggest that mid-late Holocene chronologies for the region require further investigation. Our results suggest that the study sites may have components older than previously thought, perhaps early Thule or Birnirk occupations of the coast and interior of northwest Alaska. More dates are needed from sites in this region to improve chronology and inform our interpretation of cultural change and cul­ tural interaction across the western Arctic. Researchers should incor­ porate luminescence dating into their dating tool kit, and work to build higher resolution chronologies for the region by obtaining suites of dates from sites using multiple dating methods. More broadly, our results indicate that additional ceramic lumines­ cence dating could do much to inform our understanding of cultural interaction, evolution, and transmission across the Northeast Asian and North American Arctic. Finally, our findings demonstrate that ceramic luminescence dating can be applied to low-fire hunter-gatherer ceramics in other hunting and gathering contexts, which could contribute significantly to the study of the emergence of early pottery in other re­ gions of the world. An expanded study is needed to further explore both the implications of the dates resulting from our analysis and the po­ tential challenges of the methodological application in this setting. Acknowledgements This research was funded by a National Science Foundation Disser­ tation Improvement Grant (NSF ARC-0936696), a National Park Service Murie Science and Learning Fellowship, and a Lewis and Clark Fund Fellowship from the American Philosophical Society. The University of Alaska Museum of the North and the National Park Service provided access to samples and collections information. Ross Smith assisted with fieldwork on the Kobuk River. Justin Junge and Johonna Shea assisted with figure preparation. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi. org/10.1016/j.jas.2019.105030. References Ackerman, R.E., 1982. The neolithic-bronze age cultures of Asia and the Norton phase of Alaskan prehistory. Arctic Anthropol. 19, 11–38. Adams, J.A., 1977. Archeological Excavations at Cloud Lake Village: an Early Nineteenth Century Eskimo Village on the Seward Peninsula. University of Wisconsin, Madison. Aitken, M.J., 1985. Thermoluminescence Dating. Academic Press, London. Alix, C., 2005. Deciphering the impact of change on the driftwood cycle: contribution to the study of human use of wood in the arctic. Glob. Planet. Chang. 47, 83–98. Anderson, D.D., 1988. Onion portage: the archaeology of a stratified site from the Kobuk River, northwest Alaska. Anthropol. Pap. Univ. Alaska 22, 1–163. Anderson, D.D., 1998. Kuuvanmiut Subsistence: Traditional Eskimo Life in the Latter Twentieth Century. Republished by the Northwest Arctic Borough School District, Kotzebue, Alaska. Anderson, S.L., 2011. From Tundra to Forest: Ceramic Distribution and Social Interaction in Northwest Alaska. Ph.D. Dissertation. University of Washington, Seattle. Anderson, S.L., 2016. A clay source provenance survey in Northwest Alaska: late Holocene ceramic production in the Arctic. J. Field Archaeol. 41 (3), 238–254. Anderson, S.L., Boulanger, M., Glascock, M., 2011. Late prehistoric social and political change in Northwest Alaska: preliminary results of a ceramic sourcing study. J. Arch. Sci. 38, 943–955. Anderson, S.L., Boulanger, M., Glascock, M., Perkins, B., 2016. Geochemical investigation of late pre- contact ceramic production patterns in Northwest Alaska. J. Arch. Sci. Rep. 6, 200–210. Anderson, S.L., Freeburg, A.K., 2013. A high-resolution chronology for the Cape Krusenstern site complex, Northwest Alaska. Arctic Anthropol. 50, 49–71. Anderson, Shelby L., Freeburg, Adam K., 2014. High latitude coastal settlement patterns: Cape Krusenstern, Alaska. J. Isl. Coast. Archaeol. 9, 295–318.

6. Conclusions Our primary goals were to determine whether or not low fire northern hunter-gatherer pottery is suitable for luminescence dating, and if the ceramic pastes and underlying geology of northwest Alaska were amenable to luminescence. Overall, the samples did not have the best luminescence characteristics. The lack of directly associated sedi­ ments, a problem inherent in using many museum collections, likely introduced some error into radioactivity measurements. However, despite features of insufficient firing, we were able to obtain reasonable luminescence ages on all but two samples. Therefore, we conclude that luminescence dating of ceramic materials from this region is possible 15

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