Not to muddy the waters more, but are you thinking of the swimming pool in Dawson City? Because that was movie film from the teens and twenties. I think...
That was a different discovery. I copied the text below from the Library of Congress.
This collection of early theatrical films, known more familiarly as the Dawson Collection, is most notable for its source: a Yukon swimming pool. During the summer of 1978, amid restoration of Dawson City (a gold rush era boom town in the Yukon Territory) workmen unearthed a cache of 35mm nitrate film. At the end of the distribution chain, some 500 reels had accumulated there, and in 1929 were dumped as fill in a swimming pool that had come to the end of its usefulness. The region's deep and abiding cold (still today the only known retardant of nitrate deterioration) contributed to a high survival rate of the buried treasure, although water damage took its toll, especially from the top layer. Quick, improvised action on the part of the Public Archives of Canada (now National Archives of Canada, Moving Image and Sound Archives), with the cooperation of the Library of Congress and the American Film Institute, was necessary in order to salvage the survivors. See Sam Kula's "There's Film in Them Thar Hills!" (American Film, July/August 1979) for an action- packed account of the discovery and rescue. LC has the U.S. productions, some 190 reels, and all have been preserved and cataloged.
Although a number of important, and rare, early films (including "Polly of the Circus" [1917], with Mae Marsh and "Bliss" [1917], with Harold Lloyd) were unearthed in Dawson City, many survive only as incomplete copies. There are features, shorts, several serials and some news films. Title cards are filed in the Film and Television Catalog, and copies of these cards have been collected for a subject file in the Reading Room.
