Volcanice Tuff, Leach canyon formation, Upper oligocene, 23.8Ma old
This is a relatively poorly welded tuff, with many gas vesicles (flattened by the pressure of overlying rock) and xenoliths (foreign rock), including the dark red clast in the center (likely lining of the magma chamber ripped of during the explosion). The total volume of the Leach Canyon formation is estimated to 3600 cubic kilometers (830 cubic miles) and represents the largest and apparently initial eruption of this sequence of eruptions in the Caliente-Indian Peak caldera complex straddling the Nevada-Utah border, now about 100 km from this location. This formation is about 100feet (30m) thick in this area.
Volcanice Tuff, Leach canyon formation, Upper oligocene, 23.8Ma old
This is a relatively poorly welded tuff, with many gas vesicles (flattened by the pressure of overlying rock) and xenoliths (foreign rock), including the dark red clast in the center (likely lining of the magma chamber ripped of during the explosion). The total volume of the Leach Canyon formation is estimated to 3600 cubic kilometers (830 cubic miles) and represents the largest and apparently initial eruption of this sequence of eruptions in the Caliente-Indian Peak caldera complex straddling the Nevada-Utah border, now about 100 km from this location. This formation is about 100feet (30m) thick in this area.