Northwest's Most Active Volcano Also Youngest

There has been a volcano on this site for 40,000 years -- the youngest and most active peak in a 1,000-mile Cascade Range (search) chain that extends from Mount Garibaldi in Canada to Mount Lassen in Northern California.

Like the others, Mount St. Helens (search) erupted, blasted itself apart and reformed several times over tens of thousands of years.

The perfect cone that blew apart in May 1980 began to form during the 500-year Pine Creek eruptive period that began in 1,000 B.C.

So the current mountain is about 2,500 years old -- the blink of an eye in geological time, but a period that roughly covers the history of western civilization.

The pyramids in Egypt were already 2,000 years old when the current peak began to form. Greece and Rome rose and fell as it grew.

The Klickitat and Cowlitz tribes, who have inhabited the area for centuries, called the peak "mountain of fire" in their languages.

In 1792, British explorer George Vancouver (search) named the mountain for a countryman, diplomat Baron St. Helens.

In 1836, Dr. Meredith Gairdner of Fort Vancouver logged the first written eyewitness report of an eruption.

In 1980 it erupted, reducing its height by 1,300 feet. Debris was spread as much as 17 miles northwest of the crater. The blast destroyed more than 200 square miles of forest, covered the river valley to the west with an average 150 feet of debris and killed 57 people, about 7,000 big-game animals and countless smaller creatures.