When molten rock oozes onto the
dome, it comes from a central vent. It spreads outward, usually down one
side of the dome.
When molten rock oozes onto the
dome, it comes from a central vent. It spreads outward, usually down one
side of the dome.
Most of the time this flow has a
smooth-sided crease on its surface. Geologists interpret this as the area
of spreading.
These spreading centers can be
more than 300 feet long and 200 feet wide.
The lava that forms these smooth
sided features contains less than 20% gas bubbles by volume. In
contrast, rocks that form the nearby rough texture contain over 50% gas
bubbles.
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Mount St. Helens & Other
Volcanoes
Lava Dome Features
Lava Domes
After the Eruption
Mount St. Helens
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