From Stelling and others, 2005: "Mt. Finch is a 1-cubic-km edifice in the geographic center of the caldera composed of numerous interbedded pl+ol+cpx andesite lava and scoria layers. Fumarolic activity has hydrothermally altered the western flank of Mt. Finch. Its flat summit has a raised ridge around its outside edge, and a symmetrical ~70-m-deep central depression with several large down dropped blocks. These features suggest a partial summit collapse, although eruptive deposits from such an event are not recognized. Samples from Mt. Finch are compositionally less diverse (54-60 wt.% SiO2) than those of Turquoise Cone. Mt. Finch appears less eroded than Turquoise Cone, and the pumice fall layers from Turquoise Cone are found only near the base of Mt. Finch, suggesting that Mt. Finch is younger. Erosional and effusive eruptive deposits from the two vents appear to intermingle, suggesting that activity overlapped. Several small monogenetic eruptive centers are located forund the flanks of Mt. Finch, and deposits from an ~4-square-km field of small cones have covered much of the region between Turquoise Cone and Mt. Finch."