Tracking the First Marine Mammal Hunters at Cape Espenberg, Bering Land Bridge National Preserve

By Andrew Tremayne, National Park Service

Traditionally people in northern Alaska have practiced a maritime economy. Life in the Arctic would be nearly impossible without a keen knowledge of how to harvest resources such as seals, walrus, and whales from the sea. A major archaeological research problem in Alaska concerns the timing and development of the Eskimo maritime economy. When and how did the technology and knowledge about maritime resources first develop? What kinds of evidence do archaeologists use to document the use of coastal resources in the past? 

It has been surmised that the earliest maritime culture found in northern Alaska was from people bearing tools of the Arctic Small Tool tradition (ASTt), referred to locally as the Denbigh Flint complex. The ASTt appears in Alaska around 5,000 years ago and soon after is found across the North American Arctic all the way to Greenland (Dumond 1987). The ultimate origin of the ASTt is still debated and this has important implications for understanding the origins of their maritime adaptations. Some have postulated the ASTt originated in the interior habitats of northern Alaska from caribou hunters who learned to be seal hunters (Anderson 1988, Clark 1982). Others contend the ASTt originated in Asia and spread across the Bering Strait into Alaska (Powers and Jordan 1990). If this is true, it implies ASTt foragers arrived to Alaska with a certain set of maritime hunting and navigation skills already in place. So which is it?

Aerial view of Cape Espenberg

Photo courtesy of Jared Hughey

Sleuthing Out the Timing of Coastal Settlement and Evidence for Maritime Adaptations

One way to answer the question of whether people arrived with maritime hunting and navigation skills or developed them later is to test the archaeological record by radiocarbon dating organic materials found in coastal and interior settlements. If the oldest ASTt sites are consistently found in an interior setting, it would support the hypothesis that life on the coast began after ASTt people had been in Alaska for an extended period of time. If, however, the coastal settlements appear older or contemporaneous with those in the interior, the hypothesis that maritime adaptations were already well-developed when they first arrived as migrants from Asia is supported. However, just because sites are found on the coast does not mean they were used for fishing or hunting marine mammals. Caribou, musk ox, and other terrestrial mammals could have been targeted in these areas as well. Strong evidence for maritime adaptations comes from two main sources: (1) preserved animal bones and (2) hunting and boating technology. When bones or other parts of animals are discovered in archaeology sites, researchers are often able to demonstrate through cut marks, fracture patterns, or simply through association, that the animals were hunted and processed by humans. Fishing and hunting of marine mammals requires specialized technologies that are unnecessary for hunting terrestrial mammals, such as lines, hooks, toggling harpoon heads, and other tools designed to prevent animals from escaping beneath the water. In sum, the evidence we seek to demonstrate a maritime adaptation includes: occupation of coastal habitats, specialized hunting technology, and processed marine animals preserved at the site.

Archaeological Studies at Cape Espenberg

One place that ASTt sites have been reported is at Cape Espenberg, located in Bering Land Bridge National Preserve on Alaska’s Seward Peninsula (Figure 1). Cape Espenberg is a geologic formation of beach ridges and sand dunes that have built up in a chronological sequence due to the continuous deposition of sediment from ocean currents and wave action. The beach ridge sequence extends approximately 25 km from start to tip. The youngest beach ridges are found to the north end of the cape adjacent to the Chukchi Sea, where yearly deposition continues to occur; and the oldest occur on the south side of the cape (Figure 1). The Cape Espenberg beach ridge sequence contains 126 recorded sites and a history of human occupation that spans at least 4,500 years (Tremayne 2015).

Figure 1. Archaeological sites at Cape Espenberg. Blue dots indicate 34 new sites surveyed in 2013; 12 sites were confirmed ASTt. Inset map shows Bering Land Bridge National Preserve in green.

Prior to the recent round of research at Cape Espenberg, it was unclear how frequently the ASTt camped at this location and how early their settlements dated. In the 1960s, J. L. Giddings became the first to discover evidence for the Denbigh/ASTt at Cape Espenberg (Giddings 1967). Diagnostic stone tools were collected and taken back to Brown University, but no bones or datable material was recovered (Giddings and Anderson 1986). Detailed location information was also lacking, making it difficult for later archaeological investigations to relocate these sites. It wasn’t until three decades later that NPS archaeologists returned to Cape Espenberg to systematically survey these ancient beach ridges (Harritt 1994, Schaaf 1988). The results of these NPS investigations led to the clear identification of four ASTt/Denbigh sites, two that produced radiocarbon dates indicating occupations between 3,800 and 4,200 years ago.

Goals and Methods

Our primary goals were to locate and test archaeology sites on the oldest beach ridges at Cape Espenberg to look for diagnostic ASTt artifacts, datable organic material, evidence of animal remains, and specialized maritime hunting technologies from these sites. To accomplish the survey we used systematic and random transects to locate sites. Placement of subsurface shovel tests was randomly chosen, but areas with disturbances by Arctic ground squirrels or wind erosion received careful scrutiny as buried artifacts were frequently revealed in these locations. In order to look for intact deposits, we conducted subsurface tests at locations where artifacts were observed on the surface of an erosional blowout (Figure 2). It is important to find artifacts and charcoal associated in a buried context because objects found on the surface have been disturbed and might contain a mix of artifacts representing multiple events. We sifted all sediment through a ¼” (0.5 cm) screen to capture artifacts, charcoal, or bones. We estimated the size of each site based on location of positive tests and surface distributions. We collected artifacts and samples to study back in the lab or sent them to specialists for further analysis.  

Figure 2. University of California-Davis graduate student Jeremy Foin processes items from shovel tests at Cape Espenberg.

NPS photo courtesy of Andrew Tremayne

Archaeological Findings

During this project we discovered 34 new archaeological sites (see blue dots in Figure 1) and revisited 10 known. Of the new sites found, 10 confirmed usage of the area by ASTt people. The total number of ASTt sites at Cape Espenberg is now 14, with another six probable, but requiring further testing to confirm. This project added sixteen radiocarbon dates to the record, 11 from ASTt sites. Dates range between 3,300 and 4,600 calibrated years ago (Figure 3). From these data, we can surmise ASTt people camped at Cape Espenberg repeatedly for nearly 1,300 years. 

Figure 3. Plot of the probability mass for calibrated radiocarbon dates from ASTt sites at Cape Espenberg (using Oxcal 4.2 calibration software).

Importantly, the earliest date of 4,600 years ago was found directly associated with ASTt artifacts and a large cluster of marine-mammal-oil-encrusted sand (Figure 4). Cemented sand occurs when seal oil mixes with sandy ground. As the oil hardens it cements the sand together forming a concentration as hard as sandstone. To confirm these concretions were derived from marine-based fats and were cultural in nature, we conducted a lipid analysis using gas chromatography and compound-specific stable isotope analysis (Buonasera et al. 2015). These methods allowed us to show that all of the samples were formed from marine-based fatty lipids. A total of five ASTt sites contained cemented sands, indicating common use of marine mammals, and providing the earliest direct evidence for marine mammal exploitation in northwest Alaska.

Figure 4. Cemented sand hardened from mixing with sea mammal fat and oil with embedded seal sesamoid bone (scale bar is in centimeters).

NPS photo courtesy of Andrew Tremayne

In addition to the cemented sand, we found a number of stone tools (n=20) at the ASTt sites (see Figure 6 for a selection); some of which are thought to be for sea mammal hunting. These tool forms are considered diagnostic artifacts of the ASTt culture and are used as “type fossils” to identify their sites. The function of these tool forms are generally inferred to be components of hunting technologies and tools for working antler and ivory. Of particular importance is one end blade discovered eroding into Kotzebue Sound (Figure 5). End blades such as this are interpreted to be the tips of harpoon heads used to pierce the skin of seals or other marine mammals. These ASTt tool types are typically only found at coastal sites (Giddings and Anderson 1986), supporting interpretations of their specialized use for hunting seals. 

Figure 5. A blade (approximately 1.6 cm long) interpreted as a harpoon end blade was found at an ASTt sites eroding into Kotzebue Sound.

NPS photo courtesy of Andrew Tremayne

Implications for the Timing of Maritime Skills

While the evidence is still scant, these newly discovered ASTt sites at Cape Espenberg preserved the oldest evidence for marine mammal hunting in northern Alaska to date. In fact, the radiocarbon dates also indicate the earliest ASTt occupations here predate their settlements in the interior (Tremayne 2015). If the oldest ASTt sites are consistently found in an interior setting, it supports the hypothesis that life on the coast began after ASTt people had been in Alaska for a long period of time. Contrary to this, we suggest the ASTt peoples developed maritime adaptations before their arrival in Alaska or as they arrived, instead of after a prolonged period of adaptation inland. The full extent of ASTt maritime capabilities and the timing of their appearance in Alaska both require further research, but evidence is building that Arctic maritime adaptations 4,500-5,000 years ago were probably more complex and important to colonizing populations than we have previously realized.

A selection of ASTt tool forms discovered on the oldest beach ridge at Cape Espenberg. Tool types include: (a) spear point, (b) flake knife, (c) end blade, (d) side blade, (e) scraper fragment, (f) burin, (g) harpoon end blade, (i) blade, (j-k) burin spalls, (h, l, and m) microblades.

NPS Photo / Andrew Tremayne

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