Environmental Geology lecture outline
We can start with some initial questions
are the compositional variations and physical properties of lavas?
do you melt rocks to make magma that erupts as lava?
are the sources of magma?
are types of volcanic eruptions?
Two types of volcanic constructs and their
- shield volcanos:
basaltic, low angle and very large typically, quieter eruptions,
small summit calderas, example Hawaiian islands.
- strato or composite volcanos: andesitic, high angle slopes, sometimes very large
calderas, potential for very devestating eruptions, example Mt.
is determining these two different types of volcanic constructs?
- constructive and destructive phases of
some composite volcanos.
plate settings do different types of volcanism occur in?
of Mount Hecla in the background (low white ridge) taken during
1986 UNO field trip to Iceland. Mt Hecla is one of the most active
volcanic constructs in Iceland (most recent flows in 1970s), and
is also the site of descent into the interior in Jules Verne's
Journey to the Center of the Earth.
from Iceland - land of fire and ice, and lots of basalt: some
- anomalous emergent portion of a spreading
ridge, so basalt dominated.
- case history of Heimay eruption.
- fire + ice = jokulhaups.
- hot springs and geothermal energy.
Figure of a geysir in Iceland, with a jet
of steam just erupting through the overlying water and initiating
an eruption. This feature erupted about every 5 minutes. Note
the light colored cinter around that represents silica precipitating
out of the hot waters. This activity is fed by magma and hot
volcanic rocks at depth.
on the web. Fun, extensive web resource - many others.
Next lecture outline on volcanos.
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H.D. Maher Jr., 3/6/200
to Environmental Geology course index.
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