Photos from Geology Club field trip to
Yellowstone and southern Montana mines - May 2009
Kurt
Friehauf
The Geology Club traveled to Wyoming and Montana to see
Yellowstone volcano and tour mines in southern Montana.
We started at Yellowstone. Early May is a cold time to visit the
park and we found that some of the main roads were still closed.
We didn't mind a little snow and cool air, though!
It was a
beautiful day to visit Mammoth Hot Springs! The white on the
mountains in the background is snow, but the white, steaming flat
behind us is covered with travertine deposits.
Thermophilic
bacteria thrive in the hot waters at Mammoth Hot Springs. There
was a fascinating variety of types of colonies.
The wildlife at
Yellowstone is, of course, one of the great attractions.
Bison are one
of the most undulates in the park. We steered clear of them!
There weren't
many bears roaming around this early in the season. We steered
clear of the bears, too!
The group with 
Yellowstone
Falls in the background. It was drizzling a cold rain, so
everyone's bundled up.
Yellowstone
Falls with plenty of snow and ice
There are
places where hot springs flow into rivers.
Hot plus cold = warm!
It was snowing
at the time, but the hot springs were toasty warm as long as one stayed
submerged. Getting out and dressed again was a different
matter!
Roaring
Mountain steams with heated groundwater and sulfurous volcanic
gases.
Old Faithful
geyser - where superheated groundwater boils to steam that pushes water
up over a hundred feet into the air.
There are
several geyser fields at Yellowstone, each with its own special
features.
Grand Prismatic
Spring is made colorful by different types of bacteria growing in the
water.
This geyser
melted a circular hole in the snow. Yellowstone is truly a places
of contrasting opposites!
The historic
geothermal field extends beyond the limits of the national park.
After leaving Yellowstone National Park, we explored some of the
travertine deposits that had been mined for counter tops and decorative
stone.
The travertine
was mined with wire saws to cut the rock into slabs. The
remaining outcrop reveals the internal layered structure of the
travertine wonderfully!
This hilly
landscape is what geologists call hummocky terrain. Hummocky
terrain like this can form either from landslides or as glacial
deposits.
This basalt
flow contracted during cooling, causing the new rock to fracture in a
characteristic pattern called
columnar jointing.
The fractures
form 120º triple junctions, resulting in pillas with hexagonal
cross sections. Rainwater seeps between the columns along the
fractures, chemically altering the rock along the outside edges of the
blocks.
When magma
injects into fractures in the rock, the magma cools to form a tabular
rock body called a dike. When magma injects between sedimentary rock layers, the
tabular igneous rock body is called a sill. The igneous rock pictured
here was more resistant to weathering and so sticks out as a striking
ridge.
Here is another
example of an igneous dike exposed by differential weathering of the
softer surrounding rock.
Emigrant Gulch
was a historic gold mining district. The gold occurred in stream
gravels - what economic geologists call placer
deposits. When
gold is mined from placer deposits, the gravel waste piles are called dredge
tailings or dredge
spoils. Dredge
spoils are a great way to see the wide variety of rocks that occur
upstream. We spent several hours exploring these tailings.
Montana is
beautiful!
A very smart
geologists explains contact relations for the J-M Platinum Reef outcrop
near the Stillwater Mine. The Stillwater Mine produces platinum,
which is the essential ingredient in pollution-reduction automotive
technologies, as well as food processing plants that reduce
polyunsaturated fats in our diets. There are only a few platinum
deposits in the world. The Stillwater is the only platinum
deposit in the United States! The Stillwater Mining Company
is the only thing keeping us from total dependence on other countries
for platinum and related metals. (South Africa and Russia are the
primary producers of platinum in the world).
J-M Platinum
Reef in outcrop at the Stillwater Intrusive Complex. White =
plagioclase, dark = pyroxene.
crystalsCoarse-grained,
white plagioclase engulfed smaller green pyroxene at the Stillwater
Intrusive Complex.
Harley stands
by some of the inch-scale layered igneous rock. The layers were
originally horizontal, but were tilted during uplift of the mountain
range. Layering like this is unusual in plutonic igneous rocks
that form deep within the Earth, except at the Stillwater Intrusive
Complex where layering is the norm.
Magmatic
platinum sulfide grain (circled) near large (palm-sized) pyroxenes in a
pegmatitic portion of the J-M Reef in the Stillwater Intrusive Complex.
Ophitic
igneous texture in
which a large, dark crystal of pyroxene grew around many smaller
crystals of white plagioclase. That's my finger for scale at the
bottom of the photo. Great igneous rock textures like this abound
in the Stillwater Intrusive Complex.
The Kutztown
University Geology Club after touring the Stillwater platinum
mine. The white circles painted on the rock in the background are
places where magmatic sulfides are clearly visible, indicating this was
a particularly high grade part of the orebody.
Historic Butte
mining district viewed from the visitor's overlook. The
headframes in the foreground were the entrances by which the old timers
accessed the underground mine workings. As you can see, environmental
reclamation after mining was not a concern in the olden days.
There's a new miner in town these days, though - one that is doing its
best to clean
up the mess: Montana Resources. I was very
impressed by their environmental efforts!
The Berkley
Pit - a giant vat of acidic, metal-contaminated water that formed when
mining ceased in 1982 and groundwaters began filling the old mine
pit.
Montana Resources has figured
out a nifty way to help clean this mess up! By pumping water out
o fthe pit and running it over old scap iron, the toxic copper
deposits, while the scrap iron dissolves. The iron-bearing water
is released back into the pit so it does not harm wildlife. The
copper is sold to pay for the pumping (plus a very small profit to
sweeten the deal for Montana Resources).
The Continental Pit can be
seen in the background.
Studying vein
types in the Continental pit. The copper deposit in the
Continental pit consists of many tiny veins or quartz, pyrite, and
other sulfur-bearing minerals such as chalcopyite and
molybdenite. By carefully studying which veins cut and offset
others, we can work out the sequence of events that formed the
orebody.
An example of
a thick quartz-molybdenite vein in the Continental pit. Molybdenite is
the silver colored mineral forming bands in the vein.
The group poses
in an electric shovel that was unplugged for maintenance.
A working
shovel in the Continental pit loads a haul truck with ore to be
transported to the crushers before concentration.
