Yellowstone (Wyoming, USA): Geysers
1. Zoom from Hawaii to Yellowstone.
2. I have tried to resist stacking this list of Geologic Wonders with U.S. National
Parks; There are so many spectacular ones. Though I have managed to slip
several in in my Top 5 lists!
a. But it would be inconceivable not to include Yellowstone in the list – it
is just such a remarkable place.
b. If you have been to Yellowstone, the first thing that might come to
mind is lots of people, long lines, traffic jams. It is a difficult
conundrum: places that are geologically spectacular attract a lot of
people, and that can make the place seem less spectacular. Sometimes,
in the case of caves and other delicate environments, it can even
damage or destroy the wonder itself.
c. Yellowstone was the first National Park. Anywhere, in any country! It
was passed by congress and signed into law by President Ulysses S.
Grant in 1872.
d. It actually took a while to be discovered. The name Yellowstone
(Yellow Stone), came from the Yellowstone River which was originally
called "Mi tsi a-da-zi" --- a Native Minnetaree name that translates as
“Rock Yellow River.”
e. Yellowstone was visited in 1807-8 by a member of the Lewis and
Clark Expedition, John Colter, part of left to join a group of fur
trappers. Colter saw at least one geothermal area in the northeastern
section of the park, and gave a description of a place of "fire and
brimstone," but he was recovering from wounds from battles with
natives, and most people dismissed his claims as delirium – they
called this supposedly imaginary place "Colter's Hell". Over the next
forty years, several reports from explorers and trappers told of boiling
mud, steaming rivers and petrified trees, but these too were mostly
dismissed as myth.
f. In 1856, an explorer named Jim Bridger reported observing boiling
springs, spouting water, and a mountain of glass and yellow rock. The
Civil War put an end to exploration, but in 1869 and 1870 were some
organized explorations of the area, and by 1872 it was the first
National Park.
3. There are lots of reasons to visit Yellowstone – it is a beautiful place, with tall
mountains, pretty valleys, a “Grand Canyon of Yellowstone,” waterfalls.
a. It is the best population of large mammals anywhere in North
America. Has the largest public herd of Bison anywhere (3000), also
30,000 elk, and grizzly bears, wolves, lynx, black bears, moose,
bighorn sheep, mountain goats, mountain lions, and so on.
b. It also sits up at the continental divide. The beginnings of the
Yellowstone and Snake Rivers are actually very close to each other,
but the water in the Snake River ends up in the Pacific, and water in
the Yellowstone River ends up in the Mississippi and into the Atlantic.
And because of the historical volcanic activity in the area, the river
canyons cut through the layers of volcanic ash quite dramatically.
4. But the geological reason to visit Yellowstone is the Geysers. Lots of them. In
fact, there are 300 geysers in Yellowstone and a total of at least 10,000
geothermal features. Half the world’s geothermal features and two-thirds of
the world's geysers are concentrated in Yellowstone.
a. Define Geyser (show sequence)
b. Define Geothermal features: fumaroles, mud pots, hot springs.
c. There are several regions of the Park that display huge numbers of
these geothermal features.
d. The most famous geyser is Old Faithful; can spout over 8000 gallons
in a few minutes, up to 185 feet high.
e. It is not the biggest Geyser (Steamboat), but its popularity dates back
to its regularity. The eruptions occur fairly regularly (changes over
time – ranges between 45 and 125 minutes – now about 90 minutes
between eruptions)
f. Steamboat can spew water >300 ft in the air, and can go on for 40
minutes, but is much less predictable --- a few days to 50 years!
(didn’t erupt between 1911 and 1961!)
g. Other geysers, like Beehive and Castle.
5. There are also many other fascinating geothermal features. The most colorful
are the hot springs, like the Grand Prismatic Spring and the Morning Glory
Pool. The beautiful colors are not due to a geological process --- they are due
to living organisms called extremophiles, or thermophiles; examples of the
primitive life form of archaea (one of 3 forms of life)
a. Some of the first archaea discovered were in the Yellowstone hot
springs.
b. Each spring has slightly different combinations of minerals in the
water, and different temperatures, and even the same pool will have a
range of temperatures from the middle to the edge.
c. Each is a separate zone that is preferred by a different archaea – they
are different colors, so the result is often a prismatic effect where the
color changes by the types of archaea present.
d. Remember when I talked about all the strange life forms that are at
mid-ocean ridges and the possibility that life started at a mid-ocean
ridge? This is another possibility: deep in a thermal hot spring -- you
need to be below the surface, because before there was oxygen in the
atmosphere (and so, ozone), UV radiation at the surface was deadly.
e. Big effort to figure out these strange life forms that exist in water that
is hot enough to cook most anything else
i. Scientists go and sample a pool in many different locations,
pulling out and identifying the different single-celled
organisms that live there.
ii. Strange to think that that might be related to your ancestor.
6. One of the most stunning geological features is Mammoth Hot Springs.
a. The hot water contains large amounts of calcium carbonate that
precipitates as it cools (about 2 tons of dissolved CaCO2 flows into
Mammoth each day).
b. CaCO2 comes from a deep layer of limestone – water from the Norris
Geyser Basin travels along a fault from a past EQ through the
limestone, dissolving the limestone.
c. The water is hot, 170F.
d. Makes elegant travertine terraces and flows, as the water evaporates
7. So, why is there so much hydrothermal activity spread out over the Park?
Because nearly the whole park is a giant Caldera that sits on top of an active
volcano!
a. One of the largest Calderas – 85 km across!! [explain how a caldera
forms]
b. Yellowstone Supervolcano!
c. MANY past eruptions; 3 big ones in past few million years:
i. Eruption of the >2450 cu km Huckleberry Ridge Tuff about 2.1
million years ago created the more than 75-km-long Island
Park caldera.
ii. The second cycle concluded with the eruption of the Mesa Falls
Tuff around 1.3 million years ago, forming the 16-km-wide
Henrys Fork caldera at the western end of the first caldera.
iii. Activity subsequently shifted to the present Yellowstone
Plateau and culminated 640,000 years ago with the eruption of
the >1000 cu km Lava Creek Tuff and the formation of the
present 45 x 85 km caldera.
iv. Subsequent doming occurred at both the NE and SW sides of
the caldera and voluminous (1000 km3) intracaldera rhyolitic
lava flows were erupted between 150,000 and 70,000 years
ago.
v. No magmatic eruptions have occurred since the late
Pleistocene, but large phreatic eruptions took place near
Yellowstone Lake during the Holocene.
vi. It is gearing up for the next one? Show uplift figures. Hard to
tell!!!
vii. Talk about the scale of these eruptions, and the extent of ash
fall.
viii. Petrified trees.
ix. Talk about identifying the magma chamber – water nears the
shallow magma chamber, becomes superheated (>400C!),
rises, pulling in more water. Can’t cool off the ground because
more heat comes up from below.
8. Where is all this heat coming from? Why is it there? Yellowstone is a
HOTSPOT, like Hawaii, but under a continent.
a. If it is a hotspot, there should be a track? And there is!! (show!)
b. Talk about volcanism; EQs
c. Craters of the Moon, Idaho.
d. Show tomography figure.
e. Columbia Flood Basalts;
f. Hotspot often seem to first arrive at the surface as a giant outpouring
of lava; For Columbia flood basalts, 1000s of feet of lava starting 17
Ma.
g. Question is --- for how long? Will it be under Minnesota one day?
9. Top 5:
a. Strokker and Geyser (Iceland) – original “geyser” (more later!)
b. Valley of Geyers (Kamchatka)
c. El Tatio, Andes (Chile)
d. Taupo Volcanic Zone (New Zealand)
Questions:
1) Why do you think some geysers erupt regularly (like Old Faithful) and some
do not?
2) How could the US prepare for a future eruption of Yellowstone? Should it?
http://www.yellowstone.net/geysers/