Mount Saint Helens

Changes to Earth’s Surface
Mount Saint Helen’s Volcanic Blast
USGS photo courtesy of Richard Waitt.
Copyrighted photos courtesy of Mount St. Helens National Volcanic Monument Photo Library
http://www.fs.fed.us/gpnf/mshnvm/digital-gallery/25yearsofrecoverybeforeandafter.htm unless otherwise
noted.
Mount Saint Helens is located in the state of
Washington. Observe the topographic map on the
left. What landforms other than volcanoes are
found in this area?
http://www.fs.fed.us/gpnf/volcanocams/msh/archive/hall-of-fame/20040924-measurements.shtml
Pyroclastic flow
hvo.wr.usgs.gov
http://volcanoes.usgs.gov/Hazards/What/PF/PFMSH.html
Igneous rocks were formed
from cooled lava and were
deposited at the base of this
mountain.
The deposition in the picture
on the left is pumice, an
Igneous rock.
http://volcanoes.usgs.gov/Hazards/What/PF/PFMSH.html
Prior to May 18, 1980, the hillsides surrounding Mount St.
Helens supported dense forests.
How are these trees having to adapt to the hillside
environment and its changes?
• 1978 photo, Plot AE 135, pre-eruption view
On ridges within a 5-mile radius directly north of the volcano,
the force of the lateral blast fragmented trees or ripped them
from the ground. Shards of fragmented wood became part
of the blast cloud and uprooted trees were blown off the
hillsides.
Do you think that vegetation will ever grow back? Support
and justify your answer.
1981 photo, Plot AE 135, south view
Rainfall and run-off from snow melt carved erosion gullies
on steep hillsides.
Using the picture, how would you define a gully?
1985 photo, Plot AE 135, south view
1. 
How many years have passed since the Mount Saint Helens blast?
2. 
How did this volcanic eruption change the surface of the earth? Explain
your answer.
3. 
What is created as a results of volcanoes?
4. 
Predict what the landscape will look like 10 years from now, assuming
that Mount Saint Helens does not erupt again.
2004 photo, Plot AE 135, south view