Saturday, November 3, 2012

Flash Flood Man

 Last week I had the great fortune to spend time wandering around the Cedar Mesa sandstone (one of my favorite Permian deposits) Usually I am content to examine the red and white layering. The white a nice beach sand and the red debris from the Ancestral Uncompahgre Mountains.  But this time we happened to spy some rock art high on the Cedar Mesa cliffs.

This was one of my favorite panels. The cliff face is directly above the confluence of three nice sized drainages.

Below is a close up showing the image of arms help out to the side and wavy lines extending across the picture. It doesn't take much imagination to see that the arms were once connected to a body that has ironically been dissolved by water running down the cliff face. Often times these wavy lines indicate water and so this image looks like a figure standing in belly button deep water. 

Given the location of this image at the confluence of three drainages it is not a big stretch to suggest that this figure was made to warn people of high water.  Below is a flash flood sign taken from a National Park web site. There are just a few similarities between the ancient rock art and the modern traffic sign.

Tuesday, October 23, 2012

homogeneity of rock units

Over the years I have noticed that students have a tendency to assume that rock units are very homogeneous in both shape and texture. They expect the Navajo sandstone to be made of white sand grains in distinctive sand dune cross bedding everywhere they look. When you point out "different" structures in the middle of a rock unit they get confused ( just for a short time). Most of my students also seem to expect sedimentary rock units to be of equal thickness throughout their extent. I guess I can't blame them since I am just as guilty of using these stratigraphic columns that show nice rectangles for rock units.   The White Rim sandstone is a great example of a rock unit that noticeably gets thinner as you ride east. 

A few weeks ago I had the awesome pleasure of riding the White Rim Trail in Canyonlands National Park, an 80 mile jeep track created by the atomic energy commission in the 1950's which has made more money as a tourist destination than all the uranium ore pulled out.

   The White Rim is a resistant rim of Permian aeolian beach sand that delineates the inner canyons of the Green and Colorado Rivers.

 Early in the trip you can see the thickness of the White Rim sandstone.  There is a bicycle on top of the cliff in the distance for scale...It is a big cliff.
 Again, there are dots across the gorge showing the scale of the White Rim cliff.
 Halfway through the trip you can see that the formation thickness is much less than in the first two images.
Here, near the end of the trip we can see the thin white line, all that is left of the White Rim just pinches out in the Cutler formation. The beach sand ends and the debris running off the Ancestral Rockies takes over.

Friday, September 14, 2012


While hiking around the San Juan Mountains we sometimes see some ornate tree carvings usually from sheep herders from the last century. These carvings tell us about the lonely life in the mountains these men lived.  Today I was riding down an old road when I saw what looked like a rock hammer carved into an aspen tree. I can't help but wonder what the story is behind this particular arborglyph.

Wednesday, September 12, 2012

The half moon moraine

While climbing to the top of Colorado I turned around and saw this great example of the moraine we had climbed earlier in the morning. 

The cirque above is now empty of any snow. 

Sunday, August 19, 2012

There was once ice here

I had the good fortune of changing venue last week and do some hiking in my old graduate research area in Rocky Mountain National Park. Most of my work was done in the library but here on the eastern side of the Colorado Rockies we had the chance to look at some of the evidence left by glaciers. 

In this image you can easily see  the snow field up high, the remnants of the glacier that once filled this valley. I never made it up to the snow in this valley. In other nearby places we were able to see what little blue ice that was left. 

Below the snow lies the terminal moraine of the most recent advance, a small push that we dated about 1850 ish. That date always amazed me because of the advance of white guys and their families across the North American continent while the climate could support a glacial advance albeit a small one.   

Below the highest moraine is a solid rock outcrop that has been shaped by the passage of ice. This roche moutonnee shows ice movement from above downward. The upstream side is smoothed by the ice while the down stream side shows evidence of ice plucking. The ice partially melts by pressure, fills in the cracks and then refreezes with rock chunks stuck to the ice. The rocks move down stream leaving this choppy steep hillside behind.  

Below the image although unseen here is a great U-shaped valley. It doesn't get any more classical-glacial-terrain than here.

To study for my comps, I climbed into a number of these high valleys and physically touched all that the ice had left behind. Not only was it a fun way to study but it must have worked!

Tuesday, July 17, 2012

rock unit behavior

A few weeks ago I spent some quality time "under the Wingate" my all time favorite Canyonlands rock unit. In fact, the Wingate sandstone has its own facebook page. The Wingate sandstone was formed in the early Jurassic as a large sand sea or erg in the western US. It is quite easy to find cross bedding indicative of sand dunes. The sand grains are all very uniform in size and shape which creates some great erosional formations. In these images you can see how the Wingate has eroded to make some impressive towers. This is a classic formation found once the over-laying Kayenta formation erodes away. The Kayenta formation, is a combination of siltstone, sandstones and even some conglomerates and it acts as a cap rock for the easier-to-erode Wingate sandstone. 

With the protective layers above gone, the uniformed grained Wingate starts to fall apart with equally spaced cracks running vertically down the cliff face. As time proceeds and geology happens the crack widen until there are separate Wingate towers and eventually even they will erode down to nothing. 

This area along the Green River in Labyrinth Canyon shows the whole sequence of events from a large cliff face to totally missing.

The Wingate Towers
 The Wingate Towers head on
 The whole sequence: The left side shows an intact cliff face with an intact cap rock. The towers are found in the center while the right side shows the Wingate missing from the stratigraphic sequence. 

Thursday, July 5, 2012

Class time in the back of beyond

Ah field work! well, less field work and more field sharing. This is the time of year where I head into the middle of the Colorado Plateau and share basic geology ideas with K12 teachers. We spend a day on campus at the Colorado School of Mines before we head to Moab UT to spend the next 5 days paddling down the Green River through Labyrinth Canyon. Our classroom is both the modern day transport of material down the river and the mid-Mesozoic climate of the dry arid sand dunes of the Entrada, Wingate and Navajo formations. But, it is not a one direction sharing, sure I do most of the talking but all of the teachers get together and share struggles, concerns, methods and triumphs of getting their students to understand the basic tenets of science. After a winter's worth of reading some newspaper's ideas of how our public schools are doing it is always refreshing to hear from the teachers themselves. It gives me hope about the next crop of scientists who are currently residing in Middle School.

It is truly a week of learning for all participants!

Sunrise on the river!

 Class time on the river.  We barge up and discuss the formations and their forming environments as we float past. 
 Hiking up a side canyon looking for petrified wood and dinosaur tracks. Did I mention that it was 113 degrees F that day? 

 The Wingate above the Chinle
 Moving between classrooms.

Tuesday, May 22, 2012

The Great Annular Eclipse of 2012

We timed our southwest adventure to coincide with the Annular solar eclipse visible in the western US. The National Park Service helped out by publishing a great web page with an interactive map helping us select which unit of the NPS would have the best viewing.

We chose Bandelier  National Monument in New Mexico. WE arrived a few hours before the event and so hiked around some great Volcanic Tuff outcrops made into cliff dwellings by the Ancestral Pueblos (worthy of a whole blog post by itself) 

When the time came we found a not-too-crowded overlook that faced the west and we sat down to watch. By the time the sun started to disappear there was a good little group watching. We all enjoyed the few who showed up with the proper equipment to directly view the eclipse as we only brought our trusty pin hole camera.

The ruins at Bandelier. The building material is all volcanic.

 Our camera couldn't quite capture the sun with out any filters.
 Our pin hole camera shows the annular eclipse just fine!

Monday, May 7, 2012

Visit to Shanghai

I had the pleasure of visiting China for the past month and although it was not a geology trip per say, geology is hard to ignore since life is indeed a field trip.

I was hoping to blog while on vacation but found that it was a little difficult posting anything while in China.

We flew into Shanghai Pudong airport and it was hard not to notice the low lying fields and what looked like rice paddies near the airport. Driving into the city we were treated to miles (or kilometers) of new construction of massive buildings. The scene of down town Shanghai shows the incredible buildings in the city center. Of course I am from a very small town in the inter mountain west and am unused to buildings over a few stories tall...anyway

What also caught my eye was the amount of water. There are canals and large drainage ditches everywhere. I live in an arid region and I am used to seeing irrigation canals, but these are drainage canals. 

It seems that the whole of the city is built on Quaternary deltaic sediments delivered by the Yangtze river. These sediments, a fine soft clay mixture are similar to what we find in the Mississippi delta region. It makes for great rice fields but not-so-great massive city basement. It seems that most of the new buildings have been built in the top clay layers and some have been sinking from compaction of clay as well as from the subsidence from the use of ground water. 

A water gage on a canal near Shanghai.

The down town at night, including the Oriental Pearl and the Shanghai World Financial Center, the tallest building in China

Sunday, April 1, 2012

Geology with benefits

Last weekend I had the chance to visit my favorite Permian formation, the Cedar Mesa sandstone. This formation, part of the Cutler group can be found in southern Canyonlands National Park (both the Needles and Maze) and in the type area on "Cedar Mesa" part of the Monument uplift.

This thick sandstone layer shows not only classic sand dune cross bedding but also some fantastic swirleys where water interacted with the sand. The image below was originally taken because of the hundreds of hand print pictographs (painted on rock art). The image above shows the whole wall. It was only later when I noticed the great swirley of Permian water interacting with a Permian beach.

So, this was a beach environment made with sand eroded from a mountain range that does not exist any more... geology is so cool!

Monday, March 26, 2012

Geo-anatomy of a race course

Last weekend I had the chance to run in the Canyonlands 1/2 Marathon in Moab UT. Except for the wind (It is March in the desert after all) the race was lots of fun with geology at every side. The course follows the Colorado River as it flows south towards Moab.

At the start of the course, you can clearly see many of the typical Canyonland area rock units. Starting at river level is the ever popular Chinle formation of the Triassic period. This area was a large floodplain receiving material from the Uncompaghre uplift to the east. The Chinle is most famous for its uranium ore heavily mined during the 1950's.

Above the Chinle is my personal favorite: the Wingate sandstone. This Triassic aged cliff forming formation- former sand dune is ubiquitous through the Canyonland area. Its reddish hues catch that morning light just right to make the best campsites. Making a region-wide cap rock above the Wingate is the Kayenta formation containing lots of sandstone but also beds of shale and limestone showing a change in climate from sand dunes to at least occasional stream flows.

Another stratigraphic column shot from along the race course.
As the course makes its way to Moab, the late-Triassic Navajo sandstone makes an appearance atop the Kayenta formation. This shows yet another energy regime change away from the streams of the Kayenta to yet another huge sand dunes mass like the Wingate. This image also shows some structure with the ledges of the Kayenta dipping down into the river marking the edges of the Courthouse syncline.
The course doesn't end when the Colorado River reaches the Moab fault and the collapsed salt valley that created the valley where the town sits, there are still over two uphill miles into town left to go.
Over all a very fun run on a most beautiful course.

Wednesday, February 29, 2012

AW 43, your favorite geology illustrations

In the Company of Plants and Rocks is hosting this month's Accretionary Wedge and it is all about geologic illustrations.
All types of geological illustrations qualify -- drawings, paintings, maps, charts, graphs, cross-sections, diagrams, etc., but not photographs. You might choose something because of its impact, its beauty, its humor, its clear message or perhaps because of a special role it played in your life. Let us know the reasons for your choice!

From my first geology class I have seen every form of illustration to help us imagine all that underground stuff. Some professors must have been artists in former lives with their masterpieces drawn on chalk boards (did I just date myself there?) Others, like me never graduated beyond stick drawings. Some classes showed aerial photographs while others didn't. One thing though that most geology departments had in common though were collections of wearable geological illustrations.

Now most of the classes I teach are out on the Colorado Plateau. A few years ago, the Canyonlands Natural History Association had some T-shirts designed honoring the geology of the plateau parks. I naturally grabbed some different designs including the cross section of Utah route 12. I have worn and used this garment in more than one field class. If you haven't had a chance to explore along Utah 12, I strongly suggest a trip in the near future.

T-shirts also make such great gifts for the geologist on your list. My kids who live in California bought the California has its faults shirt for a Fathers Day a few years ago.

I had the pleasure to hike across the Grand Canyon last fall. Not wanting to carry too many books, we found the classic stratigraphic column bandana. It not only was light weight and full of information but doubled as a cotton cloth to get all wet and wrap around my neck as the temperatures started to climb. I also have one for the Colorado National Monument. I teach many classes along the Colorado River near the monument and this again is a great teaching tool while on the river.

Grand Canyon Rocks, what else can I say?

An excellent resource while exploring Central Utah.
This is always a conversation starter.

Tuesday, February 14, 2012

steep drop offs and narrow shoulders

I really haven't been any where different and had nothing interesting to blog about. So even though this is a kind of a cheater blog post, I thought I would share one of the new signs put up last fall just south of town.

I do love living here.

Monday, January 16, 2012

Metamorphic Core Complex...while on vacation

I am a snow snob...I admit it. This winter has seen less-than-great ski conditions and so when the temperatures in Southern Arizona were in the mid 70 degree range we thought a visit was in order.

Our major objective was to enjoy the warmth, ogle the Saguaro cactus and hike as much as possible while wandering the hillsides above Tucson we started to notice the abundance and great examples of crystalline rock, both igneous and metamorphic rock. The outcrops we examined were not anything we were familiar with beyond a very general way. The granites appeared to have been drastically changed and the gneisses looked like they had been put through the wringer.

The mountains we were hiking in were formed in mid-Laramide time when a large detachment fault allowed a decidedly large rock mass to slide while the Catalina Mountain were arching upwards. The material that moved along the fault was metamorphosed considerably, giving us some awesome outcrops to examine. Since then, erosion and weathering has moved materials from the mountain tops into the broad valleys. Many of the hiking trails use these alluvial fans to gain access to the higher elevations. Garry at geotripper has also just recently written about these mountains

Hiking in the Catalina Mountains with examples of granite that had not been altered during the formation of the Catalina Mountains.
Further out from the mountains we came across this outcrop of mylonitic gneiss, a former granite that was abused by its passage along a detachment fault as the Catalina mountains were being uplifted 25ish million years ago.

A fun outcrop of gneiss, another remnant of movement of granite along the fault.
You can never be too careful riding your bike around interesting geology.
A trail crew with an eye for aesthetics and geology. An assortment of metamorphic rocks making a wall.
Hiking across an alluvial fan; Saguaro and geology at the same time.