White Horse Bluff is a volcano that erupted 600,000 years ago just east of the Clearwater River, about 36 km north of Clearwater. Whereas most volcanoes erupt into the air – or into the ocean bottom – White Horse Bluff erupted into the bottom of an ancient lake.
When the erupting magma came into contact with water-saturated sediments at the bottom of this lake, the resulting explosion shattered the lava into sand-sized grains that immediately began to settle – only to be
blasted upward again by another explosion as yet more magma was erupted. This process – eruption, shattering and deposition – was repeated many times, building up layer upon layer of whitish, fine-grained material called tuff breccia.
In the final phases of the eruption, the rising magma no longer exploded, but instead injected narrow dykes within the core of the volcano. When the lava within these dykes cooled, it contracted by about seven per cent, resulting in small columns at right angles to the cooling surface. Today these columns – the interior plumbing of the volcano – have been exposed through erosion. We call them the Rock Roses.
“The Rock Roses” is one of six paintings created by local artist Doris Laner as second prize in the Kids-Wild Treasure Hunt, which runs through October in Wells Gray Park. For more information, please call the Wells Gray Infocentre: 250-674-3334.