The history of Mt Garibaldi involves an initial period of volcanism (200,000-300,000 years ago) followed by a period of quiescence. Renewed activity in the last 50,000 years has rebuilt the edifice in a series of violent eruptions. As successive pyroclastic flows travelled down the mountain's gentle slopes and were deposited, the volcano took on a broad, conical form. Part of the volcano's southwest flank built out onto thick glacial ice filling the Squamish River valley. Subsequent rapid melting of the ice at the close of the last ice age removed support from the western part of the cone. The volcano collapsed, producing much of the existing rugged topography of Mount Garibaldi and Atwell Peak. This catastrophic failure left a scarp on which is exposed the internal structure of the volcano and a debris fan with an estimated volume of 150,000,000 m at the foot of the mountain north of the town of Squamish. As valley glaciers retreated, two lava flows erupted Clinker Peak, immediately north of Mt. Garibaldi. The northernmost Rubble Creek flow was party confined by a wall of ice, resulting in a lava flow over 244 m (800 ft) thick. The steep, northern edge of the Rubble Creek flow party collapsed several times, most recently in 1855-1856. The village of Garibaldi was abandoned because of the danger of future collapses. The most recent period of activity occurred shortly after the disappearance of the glacial ice filling the valley, 10,700 to 9,300 radiocarbon years ago, and ended with the eruption of the Ring Creek lava flow from Opal cone on Garibaldi's southeastern flank.