Yellowstone Lake is a very active lake.
There are all kinds of geologic and biological
processes going on, right now, today.
So it's a significant contributor to the
whole hydrothermal system in Yellowstone,
and it plays a very important role in the
geo-ecology. These processes range from
simple hydrothermal vents on the floor of
Yellowstone Lake to more complex systems
like hydrothermal explosion craters with
numerous active hydrothermal vents.
We have siliceous spires. We also have
landslides that have flowed into the lake.
The geology of Yellowstone Lake can be
broken out into two basic domains.
You have the northern two-thirds which
has been influenced by volcanic and
hydrothermal processes and you have the
southern one-third which has been influenced
by glaciation. And then the entire
lake has been effected by tectonics.
Yellowstone Lake has many hydrothermal
features in it. In our mapping, starting in
1999 going to 2003, we were able to
identify more than 650 hydrothermal vents
and more than 5 active hydrothermal
explosion craters. One of the most
interesting discoveries we found in our
Yellowstone Lake surveys was that we
identified a series of structures that are
in the northeastern part of the lake,
that are siliceous spires.
And these spires are made up of silica.
They are associated with hydrothermal vents.
We can see that they are located in
these hydrothermal vent craters or depressions,
and that these structures look like conical
features that are made up of filimentous
bacteria and diatoms and they are completely
cemented with amorphous silica.
We've determined that the ages of those
spire features are about 11,000 years old.
So that's about 5,000 years after the last
glaciers retreated from Yellowstone Lake Basin.
The one behind us here is called Indian Pond
hydrothermal explosion crater and it is
about 2900 years old - before present.
It's about 800 meters in diameter.
These are the events that we have a lot
of concern about and have a high probablity
of happening in our lifetime.
Much more than a volcanic eruption.
These are large hydrothermal explosion
craters in Yellowstone and you can see
how much larger the ones we have in
Yellowstone are compared to
those throughout the world.
One of the studies that we would like
to do in Yellowstone Lake would be to
monitor these hydrothermal domes and
hydrothermal systems a little more and so
what we want to do is deploy several
geophysical instruments such as
ocean-bottom seismometers, tilt meters,
chemical instruments such as PH meters,
instruments that will allow us to measure
the temperature of the geothermal fluids
as they are coming out of the hydrothermal
vents. And we plan on deploying these
instruments at three major places in
Yellowstone Lake and leaving them on the
floor of Yellowstone Lake for a year so
we can look at the various seizmic events
that happen during the year. We can
look at how lake level changes and effects
the hydrothermal vents. And we can also
look at how seasonal changes with the
level lowering and rising have an
influence on the hydrothermal vents.
As a geologist it's very rare that
you get to see active processes in
front of your eyes. The fun thing about
Yellowstone Lake was that when we were
mapping it, we saw these active processes
happening right in front of us.
Most of us geologists look at things
that formed millions of years ago and
we're left to thinking, what were the
processes that were involved here.
And so in Yellowstone Lake we have
multiple geologic processes operating
and then we have overprinted on this
a very active biological community.
