latent heat of vaporization

A non-geology topic for a second.

We have been canning peaches this past week and as I was waiting and waiting for the canner water to start boiling I was thinking of a quick blog post. Canning is the culinary analog for splitting firewood. Lots of work in the fall leads to fresh peaches in February. All together we have about 40 jars of peaches. That sounds like a jar a week until next summer!

yes it was night by the time we had put enough energy in the system to change states from liquid to a gas.

Working the peaches
Filling the jars

Check out how much energy it takes to boil water compared to other materials. At a point in my ancient history, I was an operator in a coal fired power plant. That is when I first learned that much of the coal we burned was to put water over the edge from a liquid to a gas. (chart taken from wikipedia)

Substance	Latent Heat Fusion kJ/kg	Melting Point °C	Latent Heat Vaporization kJ/kg	Boiling Point °C
Alcohol, ethyl	108	−114	855	78.3
Ammonia	339	−75	1369	−33.34
Carbon dioxide	184	−78	574	−57
Helium			21	−268.93
Hydrogen(2)	58	−259	455	−253
Lead[3]	24.5	327.5	871	1750
Nitrogen	25.7	−210	200	−196
Oxygen	13.9	−219	213	−183
R134a		−101	215.9	−26.6
Toluene		−93	351	110.6
Turpentine			293
Water	334	0	2260 (at 100oC)	100

Peri-glacial evidence

Last weekend we were hiking across the north facing slopes in a basin at about 13,000 feet when I saw these great examples of protalus ramparts. At one time there was a permanent snowfield above the piles of rock. Erosion happens (is that a band or a bumper sticker?) easily in the rotten San Juan Mountains of SW Colorado. The mountains fall apart easily with all of the freeze-thaw cycles that occur. The material falls with the help of gravity and rolls right down the snow bank coming to rest at the base of the snow. Now that the snow is gone we see hills of rough, angular debris that does not touch the "parent" slope.

Evidence of a colder time.

A straight on view.You can see that there is no cirque above the debris hill suggesting that this is not a moraine.

Another protalus rampart in the same vicinity. In this case, the oblique view allows you to see behind the debris hill.
Another example in the same basin and approximately the same aspect. No shortage of the raw material for talus.
Just had to add the picture of the lake.

Mesa Verde- geology and archeology

(after Wanek 1959 and Griffitts 1990)

A while ago we decided that we would spend the last of the summer explorations looking at the back country of Mesa Verde National Park. In the past few years, the park has allowed ranger led treks to look at some of the less explored regions of the park. It was one of these we decided to join.

Mesa Verde is made of basically four different formations, all of Cretaceous age. The Mancos shale forms the lower slopes and valley bottom. The Mancos is a marine shale and is ubiquitous in Western Colorado. Above the Mancos shale is the Mesa Verde Group composed of the Point Lookout sandstone, a beach front sandstone; the Menefee formation, a near sea-level marshy shale and the Cliffhouse sandstone, another shoreline sandstone. The regional dip is a shallow 2-3 degrees towards the south away from the La Plata mountains.

Many of the cliff dwelling are found in alcoves created where the permeable Cliffhouse sandstone meets the impermeable Menefee shales. The waters from rain and snow slowly percolated through the Cliffhouse sandstone until they reach an impermeable layer. The slight dip of the rock units channeled the moving water to the south creating many springs on the north facing slopes. These springs over time undercut the overlaying sandstone creating alcoves. The Anasazi (or Ancestral Puebloans) found these ready made alcoves complete with water sources a natural place to build some dwellings.

Looking up from the canyon bottom. The Menefee coal beds can be seen in the center. The cliffhouse sandstone at the top.

A large dwelling area built in an alcove created by water running through a horizontal crack. A large spring is just visible in the lower right at the bottom of the Cliffhouse sandstone.
While crossing a large expanse of sandstone we were treated to an amazing collection of hematite concretion shapes.
Another ruin showing how a spring created the alcove. The floors of the dwellings are built directly on the Menefee.
An alcove in the making right at the interface between the permeable Cliffhouse sandstone and the impermeable Menefee shales.

"The Blowout"

I spent yesterday hiking above and west of the town of Ouray Colorado. At one point we had an awesome view of what is locally known as "the blowout". This highly mineralized area is actually a Larimide intrusion effectively marking the center of the Ouray Mining District. At about the turn of the era (late Cretaceous-early Paleogene), Colorado was upset with numerous magma invasions along an ancient (Precambrian) structural zone, called the Colorado Mineral Belt. The blowout is just our little part of the whole belt. The mines in the area are all related to the laccolith that forms the blowout. I found an older paper, written in 1947 that suggests that the center of the mineralization was mainly magnetite-pyritic ores with little gold and silver but that just a short distance outward ores containing pyritic gold and even some native gold could be found. As this fall rolls around, I hope to climb up and explore some of the mines in the area and will try to share my findings. My background is notoriously blank in geo-chemistry and so as usual I will keep things simple.

I just saw that this is post #100!

The blowout, now known as a source of gravel when the afternoon summer thunderstorms deluge the small catchment area.

Another view. You can just make out parts of town in the lower left.

Forgot the camera

Last week was spent on a favorite section of the green River through Labyrinth Canyon. Because I have traveled this stretch so many times, I decided to leave the camera at home.

well

The flash flooding was awesome. Whole sand bars gone, with new ones created downstream. Almost every side canyon through Labyrinth had flashed leaving large holes through the sand that is normally found as each tributary reaches the main stem.

A lightning storm that is easily the best light show I have ever experienced. (of course lightning is notoriously difficult to catch on digits)

That will teach me.

Class time

As in most states, public K12 teachers must collect some college credits every so often in order to keep their license current. A crazy notion in Colorado is that I can't get credit for the classes I teach, so I signed up for a few classes to reup my license for the next few years. Not surprisingly, I decided to take a geology class that uses river craft to explore an area.

This class used rafts and canoes to float the Green River from the Flaming Gorge Dam through the Gates of Ladore into Dinosaur NM. It was fun exploring a site close to where I do most of my work. Many rock units were the same as on the Colorado Plateau while others were new to me. What fun! Geology aside, it was interesting to watch an instructor and see how she taught. The canoeing and rafting wasn't hard to take either. I know have my requisite credits and soon should have my license approved for the next five years.

The geologic time walk. The instructor took us on a little hike with each step as one million years, giving a whole new meaning to "that was one small step for a man". It is always fun to see how different instructors try and explain the vastness of time.

The Green River in Ladore Canyon. The Ladore formation is a Cambrian sandstone that lies above the Uinta Mountain Group, a late Proterozoic sandstone/conglomerate. Between the two is a 480 million year unconformity.
Ducky-ing into Split Mountain. One of my highlights was to look at the same evidence as John Wesley Powell and see how he came up with his two working hypothesis of an "antecedent canyon" or a "superimposed canyon".

The antecedent canyon had the river channel established first. Subsequent uplift was slow enough that the river followed its original channel as it cut deeper.

The superimposed canyon had geology first, where bedrock was deformed and then buried under sediment. At a later date, a river eroded through the sediment and eventually cutting into the harder bedrock creating a conundrum for hydrologists.

Powell's notes suggest he leaned towards the antecedent method while more modern reports lean the other way towards a superimposed canyon.
Deformation at the entrance to Split Mountain. The Split Mountain Anticline. The opposite side of Split Mountain can be seen with one of Ron's gigapan images.

Games Geologists Play

While teaching classes on western rivers, I often give descriptions of the upcoming rock units. After describing mappable units, grain size, shape, color and other macro-characterizations, I ask them to determine where the next rock unit appears as we float the river. The winner often receives an extra Oreo cookie at lunch. (A game needs a prize) Other games have included: find the river, and the ever popular where are we.

Can you find the break between the Ladore formation and the Madison limestone?

Last week we were traveling in Northern Colorado and found ourselves looking at some fantastic glacially polished rock. I was explaining to my ever-patient wife about the life and death of glaciers when we created a new game: Find the Equilibrium Line.

The equilibrium line divided the ice sheet into two parts. The upper section is where material was being added to the glacier as more snow was accumulating than melting. We can observe paleo-accumulation zones from the presence of erosional features- such as glacially polished rock.
The area below the equilibrium line is where more material was melting than being accumulated. Because there was an excess of material, ice moved from above the equilibrium line to below the equilibrium line. Paleo-ablation, or melting zones can be determined by observing depositional features such as a moraine. (The image below was shamelessly right-clicked from a google image search as it showed a moraine way better than any of my pictures.)The trick is to find the point where erosion ends and deposition begins.
Here, the elevation of the paleo-equilibrium line is is roughly 11,300 feet above sea level.

For extra cookies, or credit. a very rough estimate of the paleo-climate can be determined with some simple calculations. The difference between the "modern" equilibrium line ( approximately 14,000 feet (a number created a long time ago while in grad school) and the "paleo" equilibrium line is 2700 feet. The dry adiabatic rate is roughly 3.5^o F/ 1000 feet, giving us a rough temperature difference between the ice age maximum and now would be 9^o F.

I know that there are a multitude of factors not being taken in consideration, but this seems an easy exercise where students can observe geology, do some simple calculations and go home with an answer that makes sense.

And, of course the winner gets an extra Oreo cookie.