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Connection to the Earth Science Curriculum
Key Earth Science/Geological Vocabulary
Words-
joint: a fracture in rock
along which there has been no displacement.
rift: a fault.
flow: a stream of molten or
solidified lava.
basalt: a dark-colored
fine-grained extrusive igneous rock.
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Houghton Lava
Flow
EarthCache
This site which is behind a strip mall
in the Keweenaw Peninsula provides a great opportunity to readily
see volcanic flow from the Keweenaw Rift.
Coordinates-
N47o06.686’ W088o35.084’
Michigan has ancient rock that dates over 3.5
billion years old that originated from tectonic plate collisions
and eruptions from volcanoes. This site
is a fresh outcropping that was exposed through the building of the
strip mall. It is a great view of lava
flow anatomy. You can see where one
flow begins and another ends. Look for
the bubbly top layer to connect with the dark bottom layer of the
next flow. The image below will help
you to recognize where one flow begins and another
ends. Look for the contact points.
Figure
1.Lava flow. Anatomy of a
lava flow.
The Hawaiian Island lava flows are
smooth at the surface and are called
“pahoehoe”. The lava flows
in the Keweenaw also have a smooth surface. These smooth surfaces of basalt contained bubbly
(vesicles) areas that then filled up with minerals of various
colors.
Logging Q1: What different
colors do you see in this lava flows surface?
At this site, you also
note there is more than one lava flow. You notice that the flows
are not laying horizontal, but are on an angle. The top of the flow
is a bilious green that is bubbly with the different mineral colors
in the bubbles. The bottom portion of
the flow is a black color. Find the top
of a lava flow.
Figure 2. Houghton Lava Flow. MiTEP participants viewing
the Houghton Lava Flows.
Logging Q2: How do you know
where one flow begins and one ends?
Logging Q3: How many lava
flows are there?
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