Combined archaeological, ecological, and geologic research on Chuginadak and Carlisle Islands in the Islands of Four Mountains (IFM) probed questions about the sustainability of human settlements over the past 4000 years in the face of geologic, ecological, and social hazards. We use a human ecodynamics approach to frame the investigation and present original archaeological evidence from this poorly known region of the remote Aleutian Islands. Several village sites occupied during the last four millennia are clustered in locations that were not damaged by earthquake-induced tsunamis; however, new geologic evidence indicates that at least one volcanic eruption forced humans to abandon one or more prehistoric village sites. Combined archaeological, ecological, and geologic analyses demonstrate resilient Unangax̂ occupations of the IFM through long-term climate change as well as earthquakes, tsunamis, and volcanic eruptions with occasional community vulnerability to volcanic eruptions.

We present the results of multiproxy study of a peat deposit from Carlisle Island (the Islands of Four Mountains, Aleutians). Vegetation on the initial stage of the peat is characterized by heath vegetation dominated by Ericales indicating cold conditions at 7300–6100 cal yr BP. The appearance of Betula and Alnus is the result of long-distance transportation attributable to strong winds at this time. Sedge-grass (Cyperaceae and Poaceae) communities began replacing heath vegetation at 6100 cal yr BP because of the climatic amelioration. C/N ratios and pollen spectra remain relatively stable at 6100–2450 cal yr BP. For the CR-03 peatland, volcanic tephra contributed significantly to the Fourier transform infrared spectroscopy spectral data. Volcanic input created overlap of an aluminosilicate signal with carbohydrate vibrations. Significant changes occurred at approximately 2450 cal yr BP when there is the some evidence of cooler and wetter conditions of the Neoglacial. High values of δ15N observed at 7100–7000 cal yr BP reflect the fertilizing effect of seabird nesting colonies. A decrease in δ15N ca. 6900 cal yr BP may indicate initial settlement on Carlisle Island corresponding with harvesting seabirds. Human predation continued until a series of volcanic eruptions, which deposited Okmok II and CR-02 tephra layers at ca. 2000 and 1050 cal yr BP, respectively.

The Islands of Four Mountains island group of the Aleutian island arc is remote and difficult to access. Consequently, little fieldwork has focused on geomorphic processes and their relationship to island morphology, climatic change, and human settlement. We investigated glacial, fluvial, and slope processes on the morphologically different Carlisle, Cleveland, and Tana volcanoes. The islands were extensively glaciated at the last glacial maximum (LGM), and there is evidence for a Neoglacial advance. On the highly dissected Tana volcano, a large basin is likely the result of a pre-LGM sector collapse and subsequent glacial erosion into weak hydrothermally altered rock. Valley and moraine morphology is also influenced by hydrothermal alteration. On both Tana and Carlisle, there are sediment fans composed dominantly of thick debris flow deposits mantled by ~3 m of layered tephras, fine-grained alluvium, and anthropogenic deposits. Debris flow deposition was favored during the unstable paraglacial landscape of the early Holocene–latest Pleistocene. The earliest direct archaeological evidence for settlement is 3.8 cal ka BP, but soil geochemical evidence suggests that the islands were inhabited by 7.3 cal ka BP. This discrepancy in the archaeological record may be explained by geomorphic processes including coastal erosion and unstable geomorphic surfaces.

Using six paired terrestrial and marine organics collected in the Islands of Four Mountains, Alaska, we present a new regional correction factor, ΔR (495±20 yr), for the eastern Aleutians. We compare our ΔR with previous North Pacific marine corrections. Using the ΔR for the eastern Aleutians, we calibrated the radiocarbon dates of 80 human skeletons recovered from village site Chaluka and cave burials at Ship Rock and Kagamil Islands. These burial places contain two morphologically and genetically distinct humans—an early form called Paleo-Aleut and a later form called Neo-Aleut. Researchers have contested (1) the timing of Neo-Aleut movements into the Aleutians, and (2) Neo-Aleut interactions with Paleo-Aleuts. Our recalibrations indicate that the oldest Paleo-Aleut burial (1135 BC) occurred at Chaluka and the youngest Paleo-Aleut cave burial occurred at Kagamil during the fourteenth century (AD 1305). Neo-Aleuts buried their dead at Chaluka by AD 1375. The oldest definitive Neo-Aleut cave burial occurred during the fifteenth century (AD 1420) at Ship Rock. Eastern Aleuts buried their dead in caves for centuries, with the youngest Neo-Aleut buried at Kagamil circa AD 1865.

This first zooarchaeological analysis for the Islands of Four Mountains (IFM), Aleutian Islands, Alaska, provides data about local hunter-gatherer resource exploitation over three thousand yr. The majority of zooarchaeological material represents faunal resources that were harvested within several kilometers of villages. Our analysis shows that IFM subsistence system was shaped by the small size of these islands, which is mostly true for all of the Aleutian Islands. The archaeological middens indicate that Aleuts readily exploited new resources when they became available, expanding their dietary niche. Despite human harvesting, most faunal populations remained stable; however, Aleuts overexploited the storm-petrel colony on Carlisle Island.

The earliest durable cooking technologies found in Alaska are stone bowls and griddle stones recovered from the Aleutian Islands. This article aims to identify the function of these artefacts. Molecular and chemical analyses of carbonised residues found on their surfaces confirm that these artefacts were used to process marine resources. Both artefacts have high lipid content and C:N ratios, suggesting they were used to process oily substances. Stable isotope results of individual lipids suggest that they were used to process different sets of resources within the aquatic spectrum as griddle stones have slightly more 13C-depleted lipids than stone bowls, possibly indicating more variable use. Integration of these results with archaeological and ethnographic data leads us to infer that griddle stones were used for cooking a diversity of aquatic resources, possibly with the addition of plant foods, whereas stone bowls were specifically used to render marine mammal fats. We further hypothesize that a sudden peak in stone bowl frequencies at 4000–3000 cal yr BP was connected to a Neoglacial cold spell bringing sea ice conditions to the Aleutian Islands. This may have led to new subsistence strategies in which the rendering of marine mammal fats played a central role.

Asx̂aana-x̂ Cave in the Islands of the Four Mountains, Alaska, was excavated in 1990. The cave contained the remains of Unangan mummies and their grave goods including textile, wood, bone and stone artifacts. These mummies were buried between AD 1250 and AD 1780-1790. The mummies were distributed in three distinct areas in the front, middle and back of the large cave. The textile and wooden artifacts and their distribution have been described in earlier publications. The stone artifacts include end blades, adzes, ulus and hammerstones plus an oil lamp and a small figurine; among the bone artifacts are whale bone planks and scapulae, rods and shafts, harpoon heads and labrets. These artifacts are typical of artifacts in the Aleutian Islands, while their distribution continues to strengthen the idea of a disjunct distribution of artifacts in the cave, which I interpret as being due to different social groups using the three areas of the cave for their burials.

We discuss the cultural roles of dog and red fox recovered from Carlisle Island, Islands of Four Mountains, Alaska, within the context of Aleutian ethnographic and zooarchaeological records. Three dog bones were recovered from the Ulyagan archaeological site, Unit 5, in levels that date to AD 1450–1645. Three red fox bones come from the Ulyagan site, Unit 4, in levels that date 460 BC–AD 95. Our analyses show that both red fox and domestic dog date earlier than the contact with Russians and that these canids do not extend west of the Islands of Four Mountains archipelago. Given the rich history of human intervention on the Aleutians ecosystems over the last 250 years, we argue that indigenous red fox inhabited the Islands of the Four Mountains region prior to western contact; however, foxes did not have a pronounced cultural role for prehistoric Aleuts. Domestic dogs accompanied humans in the Aleutians after AD 950, suggesting that these canids might be linked with the Neo-Aleut culture. In the light of Arctic and oceanic cases of human use of dogs considered in the paper, we suggest that dogs might have served as reserve food sources during long trips for people migrating west.

The Aleutian subduction zone is capable of generating magnitude ~9 earthquakes that have local impact and broadcast their destructive power across the Pacific through tsunamis. Field surveys of the tsunami from the 1957 Great Aleutian earthquake (reported Mw 8.6) indicate a tsunami amongst the largest of the twentieth century. In the eastern half of the rupture zone, stranded logs record up to 18 m run-up in the Islands of Four Mountains (IFM) and 32±2 m on Unalaska Island. In conjunction with archaeological studies in the region, these observations show the potential impact of tsunamis on the ancient peoples in the IFM. Simulation of the near-field tsunami produced from the published slip distribution of 1957 is almost an order of magnitude smaller than all field observations. Increasing the earthquake magnitude and amount of eastern slip used in forward models of the tsunami demonstrate that run-up observations can be achieved throughout the eastern Aleutians if the earthquake was more than twice as large—at least Mw 8.8 earthquake with 10–20 m of eastern slip. Additionally, up to five possible IFM paleotsunami deposits agree with the regional picture of regular large events, illustrating the circum-Pacific tsunami hazard from the east-central Aleutians.

We compiled present-day observations and survey data of the avian and mammal fauna in the Islands of Four Mountains, Alaska, which primarily consist of marine-adapted species, to provide insight into the prehistoric fauna found in the archaeological record. We documented 63 bird species, mainly seabirds (67%). The majority (71%) of the estimated number of breeding birds are ledge nesters, predominately murres, and most (68%) spend the majority of their lives in the offshore environment. We lack good estimates for burrow and crevice nesters, which were impacted by and are still recovering from a period of arctic fox farming in the twentieth century. Marine mammals, predominately Steller sea lion, harbor seal, and sea otter, primarily use accessible land as haul-outs and are found in low numbers compared with the rest of the Aleutians. Red fox, the only land mammal, presently only reside on Chuginadak Island. While the present-day fauna is similar to the fauna recorded in the archaeological record, we found no indication of nesting by ancient murrelets and northern fulmars in the Island of Four Mountains, whereas both species were present in midden sites on Carlisle and Chuginadak Islands, with the possibility of prehistoric breeding colonies on Carlisle Island.