May 18th is the 30th anniversary of the eruption of Mt. St. Helens, the most documented and dramatic volcanic eruption on US soil since the founding of the republic. (Mt. Shasta may have erupted in 1776, but California was not yet part of new country; Lassen in 1917 was rather small.)

David Johnson, seen here in the picture to the right, is the eponymous geologist killed in the eruption near what is now called the Johnson Memorial Ridge. He was one of many people surprised by the sideways, lateral blast that carved out St. Helens' north side.

In many ways, I became a geologist because of this eruption, which at the tender age of 10 struck my consciousness like few things had before. I still have the dog-earred National Geographic magazines detailing the event in dramatic photos, and I spent many long hours staring intently at the glossy pages.

MSNBCS has a nice set of photos commemorating the event:

http://www.msnbc.msn.com/id/37199772/from/ET/?beginTab=1&beginSlide=1