National Geographic : 1981 Dec
After clearing its throat with a further eruption May 25, 1980, Mount St. Helens indulged in intermittent spurts of dome building and destruction in June, July, and August. An eruption October 16 to 19 brought forth a new lava mound so muffin like that it was called "Muffie," and launched a more sustained phase of dome building. Further eruptions on December 28, 1980, February 5 to 7, April 10, June 18 to 19, and September 6 to 7,1981, added im pressive breadth, height, and bulk. Will St. Helens continue to build until it surpasses its former majesty, or will it blow itself apart in a new fury of destruction? Science needs years to amass data before it can venture an answer. SLava, debris avalanche, and pyroclastic flows, 1980-1981 Rock of modern Mount St. Helens, 400 B.C. to A.D. 1857 Rock of old volcanic center, 36,000 to 500 B.C. Intrusive rock about 20 million years old Volcanic rock 40 million to 30 million years old V x COMPUTERMAPSBYDYNAMICGRAPHICS,INC. ANDUNITEDSTATESGEOLOGICALSURVEY GEOLOGICDATAFROMMICHAELDOUKAS UNITEDSTATESGEOLOGICALSURVEY ANDCLIFFORDA. HOPSON UNIVERSITYOFCALIFORNIA,SANTABARBARA COMPILEDBYDOROTHYA. NICHOLSON NATIONALGEOGRAPHIC ARTDIVISION 715 I s U * *= Dated events depicted in yellow and orange. Cumulative dome deposits shown in red.