The Bridge River Ash is a large geologically recent volcanic ash

Volcanic ash

Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...

 deposit that spans from southwestern British Columbia

British Columbia

British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

 to central Alberta

Alberta

Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...

, Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

. The ash consists of dust-sized shards ellipsoidal fragments of pumice

Pumice

Pumice is a textural term for a volcanic rock that is a solidified frothy lava typically created when super-heated, highly pressurized rock is violently ejected from a volcano. It can be formed when lava and water are mixed. This unusual formation is due to the simultaneous actions of rapid...

. It overlaps the Mount St. Helens Yn Ash and the Mazama Ash

Mazama Ash

The Mazama Ash is a large geologically recent volcanic ash deposit that covers portions of the U.S. states of California, Oregon, Washington, Idaho, Montana, Nevada, Wyoming and Utah, as well as the Canadian provinces of British Columbia, Alberta and southwestern Saskatchewan...

 which were erupted from Mount St. Helens

Mount St. Helens

Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is south of Seattle, Washington and northeast of Portland, Oregon. Mount St. Helens takes its English name from the British diplomat Lord St Helens, a...

 and Mount Mazama

Mount Mazama

Mount Mazama is a destroyed stratovolcano in the Oregon part of the Cascade Volcanic Arc and the Cascade Range. The volcano's collapsed caldera holds Crater Lake, and the entire mountain is located within Crater Lake National Park....

 about 3,400 and 6,800 years ago.

Even though the name Bridge River Ash is consistent with the Bridge River Cones

Bridge River Cones

The Bridge River Cones, sometimes referred to as the Lillooet Cones and Salal Creek Cones, is the name given to a volcanic field located on the north flank of the upper Bridge River, about west of the town of Gold Bridge...

, the ash did not originate from these volcanoes. The Bridge River Ash was created when Mount Meager

Mount Meager

Mount Meager, originally known as Meager Mountain, is a complex volcano in the Sea-to-Sky Corridor of southwestern British Columbia, Canada. It is located north of Vancouver at the northern end of the Pemberton Valley. Part of the Cascade Volcanic Arc of western North America, its summit is above...

 erupted about 2,350 years ago as prevailing winds carried the ash east during eruption. This is the most recent major eruption in Canada.

See also

• Volcanism of Canada
• Volcanism of Western Canada
  Volcanism of Western Canada
  Volcanism of Western Canada produces lava flows, lava plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calderas, diatremes and maars, along with examples of more less common volcanic forms such as tuyas and subglacial mounds.-Volcanic belts:*Anahim...