Pagosa Peak Dacite 3. Pagosa Peak Dacite (unit Tpl), a low-energy pyroclastic deposit that is a precursor to eruption of the petrologically identical Fish Canyon Tuff (Bachmann and others, 2001), forms rheomorphic lava-like rocks in areas of thick accumulations. In this outcrop at Rock Lake (northwestern Wolf Creek Pass quad), massive flow-layered lava-like rocks (unit Tpl) abruptly overlie the pyroclastic blob-and-ash unit (unit Tpb). Contact is along grassy bench, with dead branches (note two geologists, for scale). Photograph by P.W. Lipman.