Event Name : Trident Falling Mountain Dome
|Start: 70000 (± 8000 Years) || Years BP K-Ar || |
|Lava dome: ||
|Eruption Product: || dacite ||
From Hildreth and others (2003): "Falling Mountain dacite dome, the northeast face of which was sheared off (fig. 2 [in original text]) during the 1912 eruption at adjacent Novarupta, yields an age of 70+/-8 ka."
"The two largest domes (fig. 9 [in original text]), 425-m-high Falling Mountain and 365-m-high Mount Cerberus (each 0.3-0.4-km cubed volume), are compositionally similar to the smaller (unnamed) domes, which range in volume from 0.015 to 0.12 km3. Like West Trident, all the domes contain chilled enclaves (1-15-cm diam) of phenocryst-poor andesite (54-58 weight percent SiO2), although such enclaves are uncommon in the dacite of Mount Cerberus. All the domes are glacially scoured, and several are severely eroded. Mount Cerberus and Falling Mountain, however, are stout domes that are morphologically little modified by ice and were suspected of being very young (Hildreth, 1983, 1987). Repeated search has nonetheless turned up few remnants of glassy carapace, and K-Ar data now give late Pleistocene ages for both domes-Falling Mountain 70+/-8 ka and Mount Cerberus 114+/-46 ka. The superficiality of glacial erosion may reflect their compact profiles and positions close to the Alaska Peninsula drainage divide. Flanking the entrance to Katmai Pass at the northwest foot of West Trident (fig. 9 [in original text]), both domes (63-65 weight percent SiO2) have a compositional affinity (low K, Zr) with the Trident group."