Mount Diablo, California

What's documented

Mount Diablo is an isolated peak of the Diablo Range in Contra Costa County, California, rising 1,173 m on a basal terrain near sea level — one of the most prominent isolated peaks in the lower 48 states, with one of the largest viewsheds in North America (visible terrain estimated at ~100,000 km² on clear days). Sacred to the Bay Miwok, Volvon, and other Bay Area Native peoples; the Volvon name (Tuyshtak) is widely cited. A pattern of unexplained-light reports over and around the mountain has been documented since the late 19th century; the 'Mount Diablo lights' have been treated as a distinct regional UAP feature in the literature since the 1950s. Jacques Vallée, who lived in the Bay Area while at SRI International and afterward, has personally referenced Mount Diablo as a locally-resident researcher's case file in his *Forbidden Science* journals; the mountain is one of the few specific California locations to which Vallée returns repeatedly in his journal entries from 1965 forward.