Monday, September 3, 2012

Yellowstone: A Beautiful, Yet Stinky Place.

Plug Your Noses and Open Your Eyes!  It's YELLOWSTONE!

Yes, Yellowstone is one of the coolest and stinkiest places on Earth.  As a part of a geology vacation, uh, I mean field course, we took a trip to Yellowstone National Park to study groundwater systems.  We measured discharge rates and dissolved solids.  As the water moves through the rock, it dissolves certain elements and carries them to the surface.  The water at Yellowstone is chock full of dissolved goodies, much more than the water we drink.  

This spring was flowing pretty quick.  We walked to the bridge that you see in the distance and lowered the Rand-Bot to measure the depth and such.

He was glad we didn't drop him.

Can't write about Yellowstone without a few pictures of furry woodland creatures near your vehicle.

Here, we are walking on a boardwalk that allows you to get quite close to the hot springs.  The hot springs are very photogenic.  Cool meteoric (rain and snow) water enters the ground and travels downward until it encounters the hot volcanic rocks in Yellowstone's sub-surface.  The hot rock heats the water and it begins to rise.  (Remember, heat rises?)  As the hot water comes out of the ground, silica or calcium carbonate are deposited at the surface depending on the type of rock the water was travelling through.  If the rock was flowing through the volcanic rocks of Yellowstone, like rhyolite, then silica is deposited (called sinter).  If it travels through limestone, then calcium carbonate will be deposited (called travertine).  It makes some awesome, otherworldly landforms!  And the fog makes you feel like you are on another planet as well.  Look at those aliens coming through the fog!

By the way, the hot springs are the cause of the stinky-ness.

Blue, NO!  AHHHHHHhhhhhhhhhhh..........

Hot meets cold

Grand Canyon of the Yellowstone, upper falls.

Grand Canyon of the Yellowstone, lower falls.

New hot springs and steam vents will occasionally crop up at  random places.  This one has scorched the hillside over time.

So we did do some work.  Rather, Brandon did.  We watched him collect samples from water running over the side of this mound-o-travertine.  P.S.  We had permission to do all this....paperwork and everything....

More furry woodland creatures.
This is at Mammoth Hot Springs.  It was absolutely beautiful.  Everywhere you looked there were deposits like these ...and next to them, the greenest, lushest, most beautiful woods.  The trees don't stand up well to hot stuff though.  You can see some dried up goners in this terraced mound of travertine.

Near Mammoth, sink holes like these form due to the collapse of cave roofs.

What about Old Faithful?  Well, first of all, Old Faithful isn't so faithful anymore.  We had to wait quite awhile to see it go off.  The geyser is really just like any of the hot springs in the park except that it has a constriction near the surface ( the "pipe" the water travels through gets thin).  The constriction causes pressure to build.  Eventually, the super hot water reaches the surface and its pressure drops.  This causes the water to instantly turn into steam.  Then out comes Old Faithful.  After the eruption, the pressure builds again, and we wait.  I didn't get any pictures of Old Faithful because I decided to film it.  Unfortunately, the footage wasn't too great.  So here is a picture I ripped off from somewhere else.

 Old Faithful.  From here.

Monday, August 13, 2012

Death Valley, the place of dead things, deadness, and also dying.

Death Valley 

As a part of my geomorphology class, we went on a trip to Death Valley California.  It is a great place to view many surficial features like alluvial fans, salt pans, losing streams, dunes, etc.  It is such a great place for this because everything is DEAD!  There are no plants to block the geologist's view of the rocks and sediments.  

View of Badwater Basin in Death Valley from the east, looking west-ish.

So why is Death Valley so low?  It is part of the Basin and Range Province which is a part of the Earth's crust that is being pulled apart.  Death Valley has experienced both extensional (pull apart) shear and transtensional (things moving past each other and rubbing against each other) shear.  Here is a picture:

The blue area has dropped relative to the red.  This is why Death Valley is so low, in part.

From: 4D analogue modelling of transtensional pull-apart basins, 
  • Jonathan E. Wu, 
  • Ken McClay, 
  • Paul Whitehouse, 
  • Tim Dooley 
  • Marine and Petroleum Geology Volume 26, Issue 8, September 2009, Pages 1608–1623.

    The lowest spot in North America!  How far is 282 ft. or 85.5 m below sea level?

    That far...wait, what does that sign say?

    The water in the bottom of the basin is hyper-saline.  As the water evaporates, salt comes out of solution and crystallizes.  This is a very common process in arid environments.

    After all water has evaporated, a salt crust remains.

    The ONLY life we saw the whole trip, ladybugs and a tarantula (later).  Why are there ladybugs in the salt pan?  I have no idea.  If anyone can tell me why I will be happy and say "thank you".

    Me at the Mesquite Flats Sand Dunes in Death Valley.  
    Desiccation between dunes that has been recently exposed by wind scour.  You can see different levels of interdunal surfaces that look like steps leading off the right edge of the photo.  Man for scale.

    This interdunal area can be seen on Google Earth. 

    Here it is.  There are some beautiful star dunes that are formed by variable wind directions.  

    How can you not bury someone with all this sand available?  Jason Luke is the victim.

    Ubehebe Crater.  This is the result of  magma and water getting together in the subsurface...BOOM!  The groundwater was flashed into steam when magma came close to the surface.  Ubehebe is very young geologically.  Just a couple thousand years old. 

    A sailing stone at Racetrack Playa

    How the heck do they get there?  

    "The sailing stones are a geological phenomenon found in the Racetrack. The stones slowly move across the surface of the playa, leaving a track as they go, without human or animal intervention. They have never been seen or filmed in motion. Racetrack stones only move once every two or three years and most tracks last for three or four years. Stones with rough bottoms leave straight striated tracks while those with smooth bottoms wander.
    The sailing stones are most likely moved by strong winter winds, reaching 90 mph, once it has rained enough to fill the playa with just enough water to make the clay slippery. The prevailing southwest winds across Racetrack playa blow to northeast. Most of the rock trails are parallel to this direction, lending support to this hypothesis.[2][3]
    An alternate hypothesis builds upon the first. As rain water accumulates, strong winds blow thin sheets of water quickly over the relatively flat surface of the playa. A layer of ice forms on the surface as night temperatures fall below freezing. Wind then drives these floating ice sheets, their aggregate inertia and large area providing the necessary force required to move the larger stones. Rock trails would again remain parallel to the southwest winds. According to investigator Brian Dunning, "Solid ice, moving with the surface of the lake and with the inertia of a whole surrounding ice sheet, would have no trouble pushing a rock along the slick muddy floor."[4]
    A more recent theory[5] is that ice collars form around rocks and when the local water level rises, the rocks are buoyantly floated off the soft bed. The minimal friction allows the rocks to be moved by arbitrarily light winds.[6]" From Wikipedia.

    Dendritic drainage patterns on Racetrack Playa.

    The other living thing.  But not for long.  Something was wrong with his leg.

    Well, I've got to be honest, Death Valley is most interesting while sitting at home if you are not a geologist or geomorphologist.  I had a blast, but, well, I am a geologist.  The pictures are cool.

    Sunday, July 15, 2012

    Brats, and I don't mean children.

    BRAT, the word speaks for itself.  Manly.  Football.  Grilling.  etc.

    ...with sauerkraut and spicy brown mustard and a bun to hold it all together.
    Brats really are manly...."for my final wish, brats!"

    "According to legend, Hans IV. Stromer (1517-1592), a judge in the medieval times, was imprisoned for life for revealing an important political secret.  In those days, life-term in prison meant that once the dungeon doors were shut, you never again left your cell...

    My lunch.  Heavenly.

    Prisoners depended on family members for their food. Since he was a high ranking prisoner, Stromer was granted one reasonable wish. That wish was to be allowed 2 Bratwursts daily until the end of his days.So, his family made a Bratwurst so small that it could be passed through the keyhole of the prison door. In deference to the legend, all "Nürnberger Bratwurst" now made in Germany are required, by German law, to include certain ingredients in specific proportions. The law specifies that the sausages must be a certain length and diameter, and must be produced within the city limits of Nürnberg."  From here.

    Other great tidbits about the history of this manly food at that website too.

    Friday, July 13, 2012

    Turbidites! Hey! Watch your mouth!

    Turbidite Field trip with Arnold Bouma, the Turbidite Man

                Several years ago I found myself on a field trip in southern Missouri, northern Arkansas, and eastern Oklahoma with none other than Arnold Bouma the turbidite man.  The Bouma sequence is named after him.  Here are a few photos of turbidites that can be viewed on road-cuts, quarries, river bluffs, and dams.  You can't see the rocks anywhere else in the Midwest!  Too many dang-blamed (beautiful) trees!

    Turbidites and Turbidity Currents:

    Turbidity currents are a type of hyperpycnal density current that contain high amounts of suspended sediment.  The density difference between turbidity currents (higher density) and the surrounding water allows the current to move sediments great distances over short periods of time.  The gradient does not necessarily need to be very steep.  The resulting deposit is termed a turbidite.  Coarser particles settle out of the current before finer particles, which results in a normally graded (coarse at the base, finer grained at the top) deposit.  The Bouma “sequence” (1962) shows this deposit as representing five phases of settling, labeled a-e.  The “a” interval is a unit with commonly occurring scour marks and flute casts on the base.  The flow is extremely turbulent in this phase.  Coarser particles tend to settle out before finer particles.  This results in a fining upward of grain size.  Interval “b” consists of parallel lamination from the upper flow regime.  Interval “c” contains new bedforms commonly showing ripple lamination.  Interval “d” displays a second phase of parallel lamination from the lower flow regime.  Finally, interval “e” consists of the finer particles that settle out only after the current has passed.  Some layers (commonly d and e) may be missing due to erosion by subsequent turbidity currents.

    As turbidity currents pass a given point, turbulence and mixing involved in the head of the flow is responsible for a large amount of scour.  Coarser particles settle out and are deposited as the head of the current passes the point.  Then finer particles settle out followed by clay size particles.  (Bouma, 2007)

    A complete and ideal Bouma sequence consists of intervals labeled a through e, coarse to fine respectively.  (Bouma, 2007)

    An Arkansas road cut.  Distal deposits, very thin.

    Quarry wall.  Soil movement has folded the tops of these turbidites over.
    Delta lobes, splays, and channels.

    Load features at the base of a turbidite.  These form as a new turbidity current deposits sand on top of wet mud. The sand sinks in the mud as the mud oozes upward.         

    Quarry wall.

    Notice the "rythmic" turbidites, sand-mud-sand-mud-etc.

    Road cut.  Vertical turbidites.  Here you can see that the actual thickness of one Bouma Sequence can vary quite substantially.

    And just because Arkansas is beautiful...

    Dr. Loch taking notes...I think he was the only one.  Shame on the rest of us!

    Me an Arnold posing in front of some folded turbidites.

    The crew.  I don't remember everyone but I am far right.  Two over is Mitch then Dr. Bouma.  DIIIAAAAANNNNNAAAAAAAAA!!!!!!! is trying to hide and the white hard hat is held by Dr. Zellers.  Kevin is in the very back.  

                   Deep Sea Canyon Fill. Deep sea canyons are a typical path for a turbidity flow. Shock caused by tectonic movement often starts the flow. Flows usually travel through a canyon very quickly because of the steep gradient. Intra-canyon deposits typically spread laterally from wall-to-wall. The characteristic lobes that are so common in submarine fans are not present in the canyon itself. Due to the frequency and intensity of the flows inside the canyon, the finer layers of sediment are commonly stripped away by subsequent turbidity currents. This leaves only a small amount of mud preserved in the rock record.

    A representation of the Campos Basin.  Turbidite flows exit the canyons as a deep sea fan.
    (Guardado et al 1990)

                   Deep Sea Fans. Submarine fans spread out from the mouths of the canyons that feed them. Turbidity flows continue forward and begin to spread laterally because the restrictive canyon walls are no longer present. The current will follow the present channel until it is filled up with sediment. As one channel fills with turbidites, the current follows the path of least resistance and abandons the old channel to begin a period of deposition in a new channel. This is called channel switching (Walker, 1984). Channel switching results in the formation of several finger-like extensions called lobes.

                   ***Geologists care about this type of system because much of the world's oil and gas reserves are contained in the sandstones of a turbidite succession.***

    P.S.  Why are there Turbidites exposed in southern MO, northern AR, and eastern OK? Well, the Ozark-Ouachita Highlands were, at one time, deep in the ocean between the N. American Plate and the S. American Plate.  As these plates collided, the rocks in my pictures were folded and uplifted to become a giant mountain chain.  Erosion has since reduced their size drastically.  Know you know.  See here.

    Bouma, A. H., 1962. Sedimentology of some Flysch deposits; A graphic approach to facies          interpretation. Amsterdam: Elsevier Pub.
    Bouma, A. H., 2007. Active and Passive Margins Have Different Types of Depositional   Locations. Texas A&M University, Department of Geology and Geophysics. p. 6-7.
    Guardado, L. R.,Gamboa, L.A.P., and Lucchesi, C.F., 1990, Petroleum Geology of the Campos   Basin, Brazil, a model for producing Atlantic type Basin. AAPG memoir 48, p. 3-79.
    Walker, R. G., 1984. Turbidites and Associated Coarse Clastic Deposits. Geoscience Canada,      Reprint Series 1, Facies Models, Second Edition. p.178-181.