sky island
n.— «From a parched sea of desert in southeastern Arizona, Mt. Graham rises 2 miles to a crested summit above the clouds. Isolated in time and space for 11,000 years, the mountain is what biologists call a sky island, “a cradle of evolution.”» —“A Desert Mountain Versus The Stars” by Carol Ann Bassett Newsday (Long Island, New York) May 5, 1987. (source: Double-Tongued Dictionary)