The Barrier is a lava dam retaining the Garibaldi Lake system in southwestern British Columbia, Canada. It is over 300 m (980 ft) thick and about 2.4 km (1.5 mi) long where it impounds the lake.
The area below and adjacent to The Barrier is considered hazardous due to the unstable lava formation.
Garibaldi, originally named Daisy Lake and also known as Garibaldi Lodge and Garibaldi Townsite, is a locality and ghost town in British Columbia, Canada, on the Cheakamus River around its confluence with Rubble Creek and just south of Daisy Lake. The CN railway (formerly BC Rail) and British Columbia Highway 99 traverses it north–south.
Although some buildings remain, including public works facilities, the community is now officially depopulated due to the geohazard posed by the Barrier, a lava dam holding back Garibaldi Lake that has let go at various points in the past; Rubble Creek, the source of which is Garibaldi Lake, gets its name from the large boulder field created by successive degenerations of the Barrier.
A volcanic dam is a type of natural dam produced directly or indirectly by volcanism, which holds or temporarily restricts the flow of surface water in existing streams, like a man-made dam. There are two main types of volcanic dams, those created by the flow of molten lava, and those created by the primary or secondary deposition of pyroclastic material and debris. This classification generally excludes other, often larger and longer lived dam-type geologic features, separately termed crater lakes, although these volcanic centers may be associated with the source of material for volcanic dams, and the lowest portion of its confining rim may be considered as such a dam, especially if the lake level within the crater is relatively high.
Volcanic dams generally occur worldwide, in association with former and active volcanic provinces, and are known to have existed in the geologic record, in historic times and occur in the present day. Their removal or failure is similarly recorded. The longevity, and extent varies widely, having periods ranging from a few days, weeks or years to several hundred thousand years or more, and dimensions ranging from a few meters to hundreds, to several thousand.