sentences:  While some believe that these lava dams were stable, lasting up to 20,000 years and forming large reservoirs, others think they failed quickly and catastrophically as massive floods.Lava flows traveled downriver 76 miles (121 km) from river mile 178 to 254.One lava flow, from Little Springs, south of Pliocene Mount Trumbull, has a cosmogenic helium age of 1300 +/- 500 years BP.