Alkaline-chloride waters from Old Faithful

Alkaline-chloride waters from an eruption of Old Faithful flow over the edge of the white silica sinter terrace into the Firehole River.  The orange coloration on the sinter terrace is due to thermophilic (high temperature) bacteria living in the warm fluids.  Old Faithful Inn is in the background, with the wooded Summit Lake rhyolitic lava flow behind.