English: The PaleoIndians that lived near the San Quentin Peninsula and Ring Mountain in Marin County, California worshipped the immense power contained in a geothermal volcano located there.

Phreatic (or steam-blast) eruptions are caused by explosive expanding steam resulting from cold ground or surface water coming into contact with hot rock or magma.

Volcanic glass, beads of copper and other pyroclastic materials were formed in the caldera and scattered by the blasts. Each explosion left geothermal vents at the bottom of the caldera that belched superheated steam from deep inside of the Earth.

The PaleoIndians used the vents to re-melt the glass they collected. Their fused glass pieces take many forms and colors. They were so skilled at glasswork that they had the abiliity to create pictures inside of the glass with ashes.

Thermoluminescence Dating (TL) was performed on one glass piece. The results indicate and age of 5,700 years +/- 820,

English: Fused Brown, Red and Yellow Glass