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Lake Ilo National Wildlife Refuge Glimpses of Paleoindian Life

Archaeologists are frequently asked, "How do you know where to dig?" This question was answered quite dramatically at the Fish and Wildlife Service's Lake Ilo National Wildlife Refuge (NWR) near Dunn Center, North Dakota, in 1989. In response to safety concerns, the refuge's lake was lowered to allow replacement of an aging dam. The results were stunning!

Lake Ilo Tipi Ring Site

Six hundred acres of the old lake bed were literally covered by vast scatters of prehistoric stone tools, flakes, worked cobbles, hearth stones, and a "tipi" ring. Archaeologists were given a rare opportunity to view a largely intact ancient landscape swept clean of vegetation and topsoil. Before the new dam could be constructed, however, intensive studies to document and recover materials from these sites would have to be completed.

Lake Ilo Site excavation

Through a cooperative agreement with the Fish and Wildlife Service, archaeologists representing the Universities of North Dakota, Northern Arizona, and Washington State initiated various studies on the refuge. Over a six year period ending in 1994, researchers surveyed, tested, and excavated the archaeological sites on the former lake bed and nearby lands to piece together the prehistoric Indian life of the area. The survey team also documented two European-American structures, the Lake Ilo Dam and a smaller dam on Murphy Creek that were constructed during the late 1930s by the Works Progress Administration and the Civilian Conservation Corps, respectively.

Lake Ilo Dam

The archaeology of the Lake Ilo area has yielded a wealth of information about Paleoindian peoples of the northern Plains. Paleoindians are believed to be the earliest people to enter the New World from Asia during the last Ice Age. The two site localities excavated at the Lake Ilo NWR have been dated to about 10,500 years before present. Buried campsites, work shops, and flint quarries on the lakebed have produced finely made flint spear points, scraping and cutting tools, and tool preforms that are characteristic of the Folsom Paleoindian sites throughout the western Plains. Folsom spear or dart points were first documented in association with the bones of extinct giant bison near Folsom, New Mexico, in the early 1900s.

The archaeological discoveries at Lake Ilo NWR are very significant because they are very rare in the northern Plains and span more than 10,000 years of North Dakota's prehistory. This means that archaeologists can look at a continuous record of human adaptations to a changing post-glacial environment. Further, the information allows us to record changes in technology and food-getting that represent practical solutions to everyday problems.

Folsom knife

The Folsom people sought out high quality Knife River flint for making sharp, durable points, knives, scrapers, gravers, and perforators. Folsom period hunters pursued a number of a large mammals including an extinct form of bison, elk, deer, antelope, mountain sheep, and bear. Their highly mobile lifestyle within an extensive grassland east of the Rockies is reflected by short-term camps, use of more distant stone sources, and a highly efficient portable tool kit.

Interestingly, there is a great deal of evidence of prehistoric recycling. Dull or broken implements were resharpened or fashioned into different kinds of tools. Prehistoric chipped stone tool kits underwent continuous changes or transformations as hunting groups ranged farther away from flint source areas. Folsom peoples in the Lake Ilo area quarried flint, manufactured tools and performs, and occupied short-term camps. Lake Ilo Folsom sites are important because they reflect a broad range of tool production and life support activities.


The Fish and Wildlife Service wishes to thank all the individuals directly involved in the project, including co-directors Dr. Stanley A. Ahler (NAU) and Dr. Alan J. Osborn (FWS/NPS); field supervisors, Dr. Matthew Root (NAU) Lisa Shifrin (NAU), Jerry William (NAU), and Dean Mehrer (UND); project geologist, Michael E. Timpson (NAU); Dr. Alice Emerson (WSU); and, of course, the 44 crew members from 11 different states and the 13 UND students who helped make the project a successful one. A special note of thanks to Dr. Osborn for preparing this summary of the field work.

For additional information about the Lake Ilo National Wildlife Refuge contact:
Lake Ilo National Wildlife Refuge
Dunn Center, North Dakota 58626
Tel. 701-548-8110

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