How was Mount St Helens formed?

Answer 1

Mount St. Helens was formed by volcanic eruptions and flows over a long period of time.

The Cascade Mountains were formed by the collision of the Juan de Fuca Plate with the North American plate. Lava was forced upward to create volcanoes such as Mount Adams and Mount St. Helens.

The modern summit domes were the Kalama dome, formed between 1490 and 1647, and the Goat Rocks dome, formed between 1800 and 1857. These raised the mountain to its highest modern height. In 1980, the Goat Rocks dome was obliterated by the avalanche and eruption.

A new dome, as well as a surrounding glacier, have formed within the horseshoe-shaped crater. But to reach its pre-1980 size will require many more lava flows over a period of hundreds of years.

Answer 2

Mount St. Helens was formed through a series of eruptions that began about 40,000 years ago. The mountain is part of the Cascade Range and is located along the Ring of Fire, a zone of frequent earthquakes and volcanic activity. The most recent major eruption occurred on May 18, 1980, which dramatically reshaped the landscape of the area.