(excert from)
The Eruptive History of Mount St. Helens
by Donal R. Mullineaux and Dwight R. Crandell
GOAT ROCKS ERUPTIVE PERIOD
The Goat Rocks eruptive period began about A.D. 1800 with the
explosive eruption of the dacitic
pumice of layer T. This pumice
was
carried northeast-ward across Washington to northern Idaho (Okazaki and
others, 1972, p. 81) and apparently was the only eruptive product of
that time. Many minor explosive eruptions of the Goat Rocks period were
observed by explorers, traders, and
settlers from the 1830's to the
mid-1850's. The Floating Island Lava Flow (andesite) was erupted before
1838 (Lawrence, 1941, p. 59) and evidently was followed by extrusion of
the Goat Rocks dacite dome on the north flank of the volcano (Hoblitt
and others, 1980, p. 558).
The last eruption of the Goat Rocks eruptive period was in 1857,
when "volumes of dense smoke and fire" were noted (Frank Balch, quoted
in Majors, 1980, p. 36). A recent study of old records has suggested
that minor eruptions of Mount St. Helens also occurred in 1898, 1903,
and 1921 (Majors, 1989, p. 36-41). The published descriptions of these
events suggest that they were small-scale steam explosions, and none
produced deposits that were recognized in our studies.
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