This slate ulu from is from site XCB-001 on the western Alaska Peninsula, dating to the Cape Glazenap Phase, ca. 800-1000 BP.
The small slate ulu in this model was was made by unifacial and bifacial non-invasive percussion flaking. It appears as though the formerly ground edge has been unifacially retouched, perhaps to reshape it prior to resharpening. The hole was made with a stone drill to allow the slate to be tied to a handle.
The artefact is curated at the University of Alaska-Fairbanks, Museum of the North, catalogue number XCB-001-1101.
Stone tools made by grinding sharp edges on flat pieces of slate are found in large numbers across the coastal Arctic region of the Northern Hemisphere. These tools include slate spearpoints and knives of various shapes and sizes. They are particularly abundant in northern Scandinavia and the northwest and northeast coastal regions of North America. These slate tool manufacturing centres are aspects of he ‘Circumpolar Stone Age’ culture proposed by the famous Norwegian archaeologist Gutorm Gjessing in 1944. Gjessing speculated that the similarity of the slate tools across this vast region, along with other technological and cultural traits, suggested that the groups were in contact around the circumpolar Arctic coastline. Subsequent research—including detailed radiocarbon dating—refuted many of his suggestion, although his ideas still serve as a springboard for Arctic researchers. A consensus has emerged that the maritime adaptation of Arctic groups resulted in technological convergences and that north-south contacts with inland groups, living on the northward-draining rivers—or, in some regions, contact with coastal groups farther south—played a more significant role in cultural development than circumpolar contacts. According to this explanation, the convergence on ground slate tools was due to the material’s superiority in certain respects to flaked-stone tools for processing sea mammals and large fish, combined with the common slate outcrops in northern regions. Despite this, recent ancient DNA analyses have demonstrated movements of people across the Bering Strait and eastward at about ca. 5000 BP, and again at about 2200 BP, showing that circumpolar contact was occurring in prehistory.
A common slate tool in these assemblages is the edge-ground knife. These are usually flat, rectangular, and relatively thin pieces of slate with a sharp straight or curved edge ground bifacially on one margin. Versions of this type of tool are found in slate industries across the circumpolar region. In the Mesolithic period of the Republic of Karelia in northwestern Russia, ca. 8000-8400 BP, slate knives and daggers were found in male graves at Oleneostrovski Mogilnik. They were made from non-local slate and probably functioned as social markers. Slate knives proliferated in the Late Stone Age of northern Norway by ca. 5600 BP, and emerged in the Maritime Archaic in northeast Canada by 3500 BP. Edge-ground slate knives appear about 5000 BP in the Ocean Bay tradition of Kodiak Island in Alaska and similar knives were in use by ca. 3500-4500 BP by Charles Culture people in southern British Columbia. Slate knives were made alongside stemmed and notched slate spearpoints in many of these regions.
The ulu is the iconic slate knife used by Indigenous people of Alaska and Canada. ‘Ulu’ in the Inuktitut language translates to ‘womens knife’. It was used across the Arctic region of North America, and is particularly associated with the Inuit, Inupiat, Yupik, and Aleut people of Alaska. The tool is known as a uluk in Northern Labrador and sakiaq in East Greenland. A slate ulu was hafted into the side of an elongated handle made of wood, bone, antler, or ivory. The cutting edge was oriented parallel to the handle. This design allows a great deal of force to be applied to the knife because so much of the stone is encased in the handle. The knife blade was designed to wedge into the slot in the handle through friction, but sometimes this was augmented by pitch glue or tied through one or more holes bored through the slate with a stone drill. The development of social complexity from ca. 3500 BP in the Pacific Northwest of North America was facilitated by the drying and storage of salmon, and the proliferation of slate knives during that period is thought by most archaeologists to be a technological link to intensified fish processing. Archaeologists have also associated slate ulus with fish processing in the Arctic regions of Alaska and Canada.
Slate knives were used across the circumpolar Arctic—and perhaps independently invented in more than one region—because they were durable and easily resharpened and did not require specialist skills to make and maintain them. Further—and perhaps most importantly—experimental studies have shown that slate is not sharp enough to penetrate the tough skin of salmon and mammals. This was a great advantage because animal meat could be processed rapidly without worrying about inadvertently cutting through the skin. Intact skins were particularly necessary in Arctic conditions for clothing, boat-making, and shelter covers; intact skin was necessary on salmon because of the way the fillets were hung for drying. Speed in butchery was crucial for processing large quantities of salmon, several hundred fish a day, during their annual spawning cycle. Experiments indicate that slate knives are not as efficient as flaked-edge chert, shell, or obsidian tools but resharpening was easier and consumed less of the stone. Overall, a hafted slate knife was deemed a top choice among all the options evaluated. One study suggested that about 1200 kg of salmon (ca. 400 medium-sized fish) could be processed with one slate knife, requiring about 300 resharpenings by edge-grinding. Experimenters have found that for maximum fish-processing efficiency, slate knives need to be used in tandem with a sharp flaked-stone tool (for making initial incisions in the skin and cutting off the head) and a fine-grained piece of sandstone (for frequent resharpening).
Slate ulus were eventually replaced by metal ulus when metal became widely available, although metal was initially resisted. The Russian naval officer and explorer Lavrenty Zagoskin made ethnographic observations on the Yukon River delta in 1842-1844, and noted that the local people considered metal knives as ‘unclean’ because they came from the Europeans; they would not used them to butcher beluga whales. The slate element was largely replaced by steel by the 1900s, although the overall design of the tool was retained, with elaborations occurring in the handles. The steel blades were cut from saw blades. Ulus continue to be made by First Nations people, and have become important symbols for Arctic traditional culture. They are presented as awards for outstanding achievements: the gold, silver and bronze medals awarded to athletes in the Arctic Winter Games are shaped like an ulu.