| In the Glacier Peak area, the three principal episodes of Cenozoic igneous activity have been the intrusion of the tonalite-granodiorite Cloudy Pass batholith in early Miocene time ... the extrusion on and near the exposed batholith of a thick pile of predominantly andesitic to dacitic breccia, tuff, and lava of Gamma Ridge between early Miocene and Pleistocene time, and, in late Pleistocene and Recent time, the growth of the dacitic Glacier Peak volcano, which was accompanied by eruption of small amounts of basalt from separate vents near Glacier Peak. -- Tabor and Crowder, 1969 |
