This study discusses Native American people’s current attempts to preserve memories of tribal sovereignty through the National Historic Preservation Act of 1966, NHPA (as amended through 1992). The paper focuses on the Northern Cheyenne tribe which has been one of the most active native entities in terms of registering their sacred sites and battle sites as the National Historic Sites (NHS) and the National Historic Landmarks (NHL).

In the late 19th century, the Northern Cheyenne tribe fought the Indian Wars. In the mid-20th century, they reclaimed their sacred land, the Black Hills, through the Indian Claims Commission. At the time of the Indian Termination Policy (the 1940s and 1950s), the tribe defended their reservation by establishing the Tribal Land Acquisition Program. During the national energy crisis of the 1970s, they fought against energy conglomerates, successfully canceling the unjust coal lease agreements. The study views the tribe’s current efforts to register tribal memories as national historic sites, as a way to preserve integrity of their homeland as well as to argue against U.S. national history.

In the 1980s, Native tribes defended their sacred sites using the Free Exercise Clause, but lost cases to land developments. One of the federal/administrative responses to these court decisions was the 1992 NHPA amendment which mandates federal agencies to consult with Native tribes in order not to damage their sacred sites. Since the Civish case (2004) declared the historical importance of the Native’s sacred sites, the amended NHPA has encouraged the Native people’s efforts to preserue their land and heritage. The Sand Creek Massacre NHS, the Rosebud Battlefield NHL, and the Wolf Mountain Battlefield NHL are some of the sites which the Northern Cheyenne tribe successfully registered as the National Register of Historic Places (NRHP). While the protection of the NRHP is promised by U.S. National Park Service (NPS), the tribe’s motives behind the NRHP applications varies; in some cases, to protect the integrity of the reservation by guarding the surrounding area, and in other cases, to keep tribal memories alive in order to compose a history from their point of view.

The NPS has a history of removing Native tribes from the area designated as National Parks, and now they are willing to embrace some of the tribal memories as a part of U.S. national history. While so far, outcomes of the negotiation between the two parties has been favorable to Native tribes, the NPS’s scope for the NRHP is still limited, mostly to battle sites. It is uncertain as to what extend the NRHP effectively functions as a means for the Native tribes to defend their land. For the Northern Cheyenne tribe, the historical interpretation of the Sand Creek Massacre has been under negotiation with the NPS, and the site’s General Management Plan is still a work-in-progress. The Native tribes’ efforts to register tribal memories as the NRHP continues to pose a deep question to the national narrative of the United States.

 Natural ionizing radiation, which potentially affects biota inhabiting the Earth, can be broadly divided into two types according to origin: cosmic radiation and subsurface radiation. Cosmic radiation contains galactic cosmic rays and solar energetic particles. Subsurface radiation is derived from radionuclides such as uranium, thorium, and radon. The levels of these forms of natural radiation were not constant temporally and spatially, and underwent a lot of changes in the early Earth environment. However, the ground level radiation dose rate of secondary muons derived from a supernova event that causes the most severe biological effects among forms of cosmic radiation is estimated to be 1 sievert (Sv) per year at most, which is too low to have lethal and mutagenic effects on terrestrial microbes. On the other hand, a nuclear fission chain reaction occurred in Oklo uranium ore deposit in Gabon about 2 billion years ago and continued intermittently for 10⁵-10⁶ years. The average total radiation dose rate of a typical natural fission reactor in Oklo is estimated to be 47.4 Sv per hour. This value is high enough to serve as a physical mutagen for subsurface microbes inhabiting areas near the reactor, and a million years is long enough to generate a new species of microbes. The observed growth-inhibitory critical dose rate for Escherichia coli is estimated to be 36 to 67 Gy per hour. On the other hand, the radioresistant bacterium Deinococcus radiodurans is shown to be cultivated without any growth delay at up to 126 to 180 Gy per hour of gamma rays. Recent EXAFS and isotopic analyses indicate that biogenic processes are more important for uranium ore genesis than previously understood. D. radiodurans and its closely related species Thermus thermophilus are shown to have the ability to reduce U(VI) to U(IV) under anaerobic conditions. These lines of evidence suggest that a common ancestor of Deinococcus and Thermus might be involved in the formation process of Oklo uranium ore deposit. Therefore, the radiation dose rate at Oklo-type natural nuclear reactors would be suitable for affecting the growth of microbes and generating genome evolution through accumulated mutations.