Bennett Lake Volcanic Complex facts for kids
Quick facts for kids Bennett Lake Volcanic Complex |
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|---|---|
| Geography | |
| Location | British Columbia/Yukon, Canada |
| Parent range | Boundary Ranges, Coast Mountains |
| Geology | |
| Age of rock | 50 million years |
| Mountain type | Caldera |
| Last eruption | Eocene |
The Bennett Lake Volcanic Complex (BLVC) is a huge, ancient, and extinct volcano. It is about 50 million years old and is a type of volcano called a caldera. This giant volcano stretches across the border between British Columbia and Yukon in Canada. You can find it near the western part of Bennett Lake. The area around this old volcano is mostly made of hard, granitic rocks.
This volcanic complex is located near the edge of the Coast Plutonic Complex and the Whitehorse Trough. Inside the caldera, there are thick layers of rocks made from volcanic ash and broken rock pieces. Parts of this massive caldera complex are still visible near Bennett Lake in the Coast Mountains. These rocks are part of what geologists call the Skukum Group.
How the Volcano Formed and Erupted
The Bennett Lake Volcanic Complex was created when a giant piece of Earth's crust, known as the Kula Plate, slowly slid underneath North America. This process, called subduction, happened during a time called the early Eocene period.
Giant Explosions
The Bennett Lake Volcanic Complex had huge, explosive eruptions. Molten rock and gas burst out from cracks in the ground that were shaped like arcs. These eruptions shot out about 850 cubic kilometers (which is about 200 cubic miles) of super-hot ash and rock. These glowing avalanches are called pyroclastic flows.
Caldera Collapse
When the molten rock (magma) underneath the volcano emptied out, the ground above it collapsed. This happened in several stages, forming two big, bowl-shaped craters called calderas. One caldera formed inside the other, creating an oval-shaped dip in the ground. This dip was about 19 kilometers (12 miles) wide and 30 kilometers (19 miles) long. The calderas were very deep, ranging from 200 meters (660 feet) to 2,700 meters (8,900 feet) deep.
After the Collapse
Even after the ground collapsed and the calderas formed, the volcano kept erupting for a while. Molten rock pushed up into cracks, forming walls (called dikes) and other rock formations. These dikes cut through older volcanic layers. Many dikes formed along circular cracks and fault zones at the southwest edge of the caldera. As the volcano became less active, magma pushed up one last time. This caused the ground above the magma chamber to bulge into a wide dome, rising about 1,500 meters (4,900 feet).
