Figure 4. Photographs showing pre-Caetano caldera geology. (A) Chert-pebble conglomerate underlying caldera floor near Caetano Ranch in the northern Toiyabe Range. Rocks are thought to be part of the Pennsylvanian-Permian Antler Overlap sequence. Hammer is 46 cm long. (B) Middle Tertiary conglomerate forming caldera floor on northwest side of the Toiyabe Range. Well-lithified, non-calcareous conglomerate contains clasts of Paleozoic quartzite, chert, and argillite, Mesozoic(?) granite and diorite, and several textural types of Tertiary flow-banded rhyolite (Tr) up to 1.5 m in diameter. (C) View looking south along the crest of the north end of the Fish Creek Mountains. Questa in foreground is formed by flat-lying tuff of Cove Mine that fills a paleovalley. Higher part of range in background is comprised of Fish Creek Mountains Tuff that fills the younger Fish Creek Mountains caldera. (D) View north of Horse Mountain, Wilson Pass, and north margin of the Caetano caldera. Horse Mountain composed of Paleozoic quartzite and argillite (Pz). Caldera-bounding fault lies at base of talus slopes. Low area of Wilson Pass composed of poorly exposed mesobreccia (Tcb; Fig. 6D). Densely welded intracaldera Caetano Tuff (Tcc) forms ridge in foreground and dips 40° east (right).