Projects designed, Team Jurassic Utah begins fieldwork

May 18th, 2018

Santa Clara, Utah — Galen Schwartzberg (’19) and Ethan Killian (’19) now have their specific Senior Independent Study topics, and so today we began to collect data and specimens. This is always a special time because students have so many possibilities they must narrow down to testable hypotheses that we can practically pursue. Galen is now working on the sclerobionts (hard substrate dwelling organisms) of the Carmel Formation (Middle Jurassic) to compare them to global equivalents, and Ethan is looking at the distribution, shape and size variations, and construction of ostreoliths (“oyster balls”).

Our day began with a delightful meeting in Gunlock. Jay Leavitt (in the overalls) and Judy Leavitt (in red) showed us many local rocks and fossils, and helped us navigate the ownership of the land in our study area. They had great stories about life in Gunlock, and many observations of the local geology. They own and operate a gravel pit, so rocks are a way of life for them. They were very generous with permissions and advice. We hope to see them again on this expedition. (Photo by Nick.)

Ostreoliths and their stratigraphic contexts were the main research topics today in the field. Within a few minutes of arriving at our primary ostreolith site near Gunlock (C/W-157), Nick found these four oyster balls nicely lined up in an outcrop. These are in situ, meaning they are in place in the rocks, not rolled down the slopes like most oyster balls in the field. This meant we could plot out the single horizon of ostreoliths and place it in a stratigraphic column. Nick saved us much work by finding the critical exposure right away. (One, I must add, I walked by without seeing many times.)

The terrain is a bit difficult for stratigraphic description (or I’m getting more wobbly on steep slopes), but we set to work making a column. Here I’m showing how to measure a section with a Jacob’s staff (the striped pole behind me). This section has significant covered parts, so we used the contact with the overlying Iron Springs Formation as our datum. The beautiful yellow-red limestone behind us is designated 157-2. (Photo by Nick.)

Here is the stratigraphic section. Ethan (the student standing lowest on the slope) is at the ostreolith horizon. The thick conglomerate at the top is the Iron Springs Formation base.

Here’s a close view of the cross-bedded limestone unit 157-2. The Jacob’s staff is divided into 10 cm intervals. (Photo by Galen.)

That resistant limestone now known as unit 157-2 has the best trace fossils and ripplemarks in the Carmel, and it is less than a meter thick.

At the end of the day Ethan and Galen began measuring the primary dimensions of the oyster balls, starting at the western end of our sampled horizon and working east. This way they not only will have lots of size data, they can see if there is a gradient of shape and size change. Stay tuned for results.

A Folklore Footnote: Jay Leavitt showed us these flattened limestone clasts that erode out of the Iron Springs Formation basal conglomerate in the Gunlock area. He said that as kids he and his friends called them “Devil’s Dollars”, which they believed had “dark and mysterious powers”. This must be a universal childhood legend that takes many forms. For me the currency was old tiles carefully excavated from a dump in my hometown. Jay told us what Devil’s Dollars were really good for — skipping across ponds!

Team Jurassic Utah on the Ranch

May 17th, 2018

Santa Clara, Utah — We were fortunate today to work on the land of Eagle Mountain Ranch just north of Gunlock, Utah. The owners, Hyrum and Gail Smith, met us in the morning in their gorgeous ranch home (shown most effectively in this flyover video) and generously gave us permission to explore the Carmel Formation on their extensive properties. The above outcrop of Carmel Formation topped by the Iron Springs Formation is the most dramatic exposure. We spent most of our time on it. (Preliminary location tag EMR.)

This is a screen capture from the video describing the Eagle Mountain Ranch. Spectacular, and they have Airbnb accommodations! The white rocks in the upper left are Carmel.

Gail Smith guided us on the ranch roads to reach our outcrops. Very kind of her.

Galen at work chipping away at fossils on Eagle Mountain Ranch Cliff, as we call it. Photo by Nick.

This location has fantastic ooids which weather in slight relief, producing these exquisite bedding plane slabs.

The trace fossils here stand out with their granular surfaces of ooids. This is the bottom of the bed, thus hyporelief.

Ethan found this example of Lockeia, a bivalve escape trace, preserved again as convex hyporelief (on the bottom of the bed). This specimen is cool because it is festooned with the star-shaped colmnals of Isocrinus.

We found this hardground at the Eagle Mountain Ranch Cliff locality. The whitish encrusters are the bivalves Plicatula.

Twisty wormtubes are common on bivalve shell fragments. I don’t think these have been described.

This is one of the few places where the actual contact between the Carmel Formation (Middle Jurassic) and Iron Springs Formation (Late Cretaceous) is visible. It is a disconformity with a considerable hiatus (interval of time not recorded, up to 100 million years in this case).

Team Jurassic Utah walking back to the vehicle, with the white Carmel Formation in the background. It was a good day thanks to ranch owners Hyrum and Gail Smith. (Photo by Nick.)

Tomorrow the students begin their individual projects!

Team Jurassic Utah sets to work

May 16th, 2018

Santa Clara, Utah — Team Jurassic Utah had its first day in the field, and it was excellent. As you might recall from this blog, last month I visited southwestern Utah alone to scout out locations for this crew, and today we began work. On the left is Galen Schwartzberg (’19), in the middle is Ethan Killian (’19), and on the right is our geological technician Nick Wiesenberg. They are at Gunlock Reservoir with the delicious Middle Jurassic Carmel Formation exposed in the background. Note the beautiful blue sky. Perfect geology weather.

Classic professorial pointing at Gunlock Reservoir. Photo by Nick.

This is the familiar southwestern Utah stratigraphic column, modified after the column on the Zion National Park website.

We spent the morning exploring the Carmel exposures around Gunlock. At this point we’re doing orientation and working on observation skills. The students proved to be quick studies with the stratigraphy and paleontology, adding already new ideas and information about the Carmel fossils. No one can resist the fascinating oyster balls of the Carmel (officially they are ostreoliths), so Nick, Ethan and Galen found new horizons and worked out a rough stratigraphy of their occurrence. In some places they are so common they’re stacked up. We noted a pattern of shape distribution (spherical vs. flattened), and that the large ostreoliths (up to 75 cm in diameter) seem quite different in origin from the more numerous small ones like those shown above.

Here we were able to determine that the large ostreoliths are consistently stratigraphically below the small ones, and there are subtle changes in sediment color enabling us to predict their distribution. It is 12.6 meters from the large to the small ostreoliths, stratigraphically, and 16.9 meters from the small ostreoliths to the base of the Iron Springs Formation.

The team tramping through the Gunlock region. Note the landmark conical Veyo cinder cone in the background. Photo by Nick.

The Gunlock area we examined in the morning is #1 on the above image. We then drove north through Gunlock to Veyo (top of the image) and turned south on Utah Hwy 18 past the extending Carmel outcrops in Dammeron Valley (#2) to work in the Carmel in suburban Diamond Valley (#3). There we found many shelly fossils, mostly bivalves and crinoids, and numerous tiny encrusters and borings.

I ended the day by giving a presentation to the SW Chapter of the Utah Friends of Paleontology at Dixie State University. I talked about the origin of oyster balls, oddly enough, and what they tell us about the paleoenvironments of the Middle Jurassic in southwestern Utah. It was a fun and inquisitive group with excellent questions and ideas about some of the remaining oyster ball puzzles.


Climate Monday: The xkcd Earth Temperature Timeline

April 30th, 2018

It’s the final week of the semester, so it’s time for a little fun in the world of weather and climate visualizations.  One of the toughest things that Geologists have to deal with is conveying a sense of time scales.  It’s difficult for present-day humans to conceive of how long ago (or recent) the Roman Empire or Han Dynasty were, let alone 4.6 billion years of Earth history. We often use interesting comparisons, like how the time gap between Tyrannosaurus (68-66 million years ago) and humans is smaller than the gap between Tyrannosaurus and Stegosaurus (155-150 million years ago).  Sometimes we use analogies, like how an average human lifespan is 0.00000204% of all Earth’s history, which is about the same percentage of your life you just spent reading this paragraph.

With climate change, scientists often are approached with the question: “Climate has changed before, so why is this time worse?” An important is that this time it’s changing very fast, and rapid change is more problematic than gradual change. The faster the change, the harder it is for plants and animals (and humans) to adjust.  But conveying that sense of rapid change can be difficult when our time series are so long, stretching tens of thousands of years.  It rarely looks good on a single powerpoint slide or a single 8 1/2″ by 11″ piece of paper.  You either have to scrunch everything into a very condensed and crowded graph, use an inset box to zoom in on today, or use multiple slides/figures.  Or… you could use the tendency for modern webpages to scroll indefinitely to convey a sense of time.  This is the tactic of the webcomic xkcd.

No, seriously. The main reason for reading the comic is to laugh at the little bits of humor slipped in, but Randall Munroe at xkcd is diligent about scientific research.  The temperature data for the visualization are based on a combination of  HADCRUT4 (from the UK Meteorology Office), the Intergovernmental Panel on Climate Change (IPCC, funded by the UN), and peer-reviewed journal articles in the journals Nature (Shakun et al. 2012), Science (Marcott et al. 2013), and Climate of the Past (Annan and Hargreaves 2013). Those last three are all paleoclimate reconstructions.

Climate Monday: “Reanalysis”

April 23rd, 2018

There’s two weeks left in the semester, so today on Climate Monday we’re going to take things to the next level and highlight not only visualization, but also analysis of climate data.  Most of the big papers in climatology nowadays involve more data than you can shake a stick, and they require so computer science chops to make happen.  However, if you’re in the exploration phase, going through all that coding can be excessive work and it’s better to have a quick-and-dirty tool to get a sense of what’s going on.  The tool my PhD advisor always uses is the NCEP/NCAR reanalysis compositor.  “NCEP” is the National Center for Environmental Prediction and “NCAR” is the National Center for Atmospheric Research. But what is a “reanalysis”?

What is a Reanalysis?

Figure 1: How to create an atmospheric “analysis”. Credit: NOAA

Well, to start we have to define an atmospheric “analysis”.  And to do that, we actually need to start with an atmospheric weather “forecast”.  Whew. A weather forecast might be familiar; it’s an assessment of what atmospheric conditions are likely to be sometime in the future.  Today, our weather forecasts are derived from weather models.  We may like to joke about how bad they are, but for predicting the weather an hour from now, weather models are extremely accurate throughout most the US (especially in flatter areas like Ohio). However, these models are not perfect, and the analysis process accounts for that.  To make an analysis, you also need to gather a bunch of atmospheric observations.  These can be from a variety of sources, like aircraft, ships, land-based stations, weather balloons, or satellites. If you take, for example, the wind forecast for 6 AM that was made back at 5 AM (i.e., the 1-hr forecast — Step 1A in Figure 1) and then compare it to observations (Step 1B), you’ll find that they don’t line up perfectly (Step 2). The “analysis” step is to alter the 1-hr forecast so that it more closely matches the observations (Step 3).  The best solution usually is not to make the forecast perfectly match observation points, because observations have error too.  Indeed, the model is often more accurate in places that are remote (e.g., the Arctic Ocean) or notoriously “noisy” for data collection (e.g., Mount Elbert in Colorado). The result of this assimilation process is the “analysis” (Step 4).  This analysis then becomes the input for the next 1-hr run of the weather model.

The difference between an “analysis” and a “reanalysis” is that the former is operational while the latter is academic.  In practice, weather forecasters are constantly tweaking their models to improve forecasting, but that can lead to weird biases in long-term data; model output from 1980 is not directly comparable to model output from 2015.  So with a “reanalysis”, researchers decide on a single model set-up and re-run everything. That’s right: for every hour, they re-run the model, re-run the assimilation of observations, and spit out an analysis.  This is what the NCEP/NCAR reanalysis tool is, and it’s a great way to start thinking about climate analysis instead of just weather analysis.

Examples from NCEP/NCAR Reanalysis

We’ll stick to surface temperature, because that’s a pretty simple variable to talk about, but note that you can look at a whole suite of variables from multiple levels in the atmosphere. It’s not very detailed information — you can’t use this tool to think about individual cities — but for a broad view, you can see, for example, that average temperatures in the US in March ranged from sub-freezing in Minnesota to over 20°C (68°F) in southern Florida. Note, it’s much worse up in Hudson Bay, where temperatures averaged about -15°C (5°F). (Figure 2)

Figure 2: Average surface air temperature in Mar 2018 compared to 1981-2010 average. Source: NCEP/NCAR Reanalysis

You can also check out how March 2018 compared to “normal” (meaning the average from 1981 to 2010). As noted a few weeks ago on this blog, northeast Ohio and Virginia and eastern Montana were all cooler than average by a few degrees.  Of course, Texas was a little bit warmer than average. (Figure 3)


Figure 3: Surface air temperature anomaly in Mar 2018 compared to 1981-2010 average. Source: NCEP/NCAR Reanalysis

That’s good, but you can see all of this at NOAA’s website, too for the past month with fewer clicks.  So what makes the NCEP/NCAR compositor special is the ability to composite random years together and keep experimenting until the cows come home.  For example, did you know that in the autumns (Sep, Oct, Nov) with presidential elections, years in which the USA elects a Democrat tend to be cooler in the East and warmer in the West?  (Figure 4). Now, I don’t think that’s a significant result, and I doubt it really means anything.  On the other hand, knowing politics, don’t be surprised if you start seeing Republicans with hair dryers in Michigan come October 2020.

Figure 4: Difference in Sep-Nov surface air temperature between years in which a Democrat won the presidential election in the US minus years in which a Republican won. Source: NCEP/NCAR Reanalysis.

Wooster Geologist in Southwestern Utah (April 2018)

April 21st, 2018

St. George, Utah — I visited southwestern Utah for a week to prepare for an Independent Study expedition next month to study the Carmel Formation (Middle Jurassic). I wanted to update locality information I had collected in the 1990s (ancient times!), find different sections, and meet new people. It was much fun and very productive. The daily blog entries are linked below —

April 16: A Wooster Geologist returns to the Jurassic of southwestern Utah
April 17: Another geological scouting day in southwestern Utah
April 18: Another day in the shallow Jurassic seas of southwestern Utah
April 19: Delightful fossils in the Middle Jurassic Carmel Formation on my last field day

Next month we will have posts from the project!

New article: Paleoecology of an Upper Ordovician submarine cave-dwelling bryozoan fauna and its exposed equivalents in northern Kentucky, USA

April 20th, 2018

I’m happy to link to an article on Ordovician bryozoans that has just appeared in the Journal of Paleontology:

Paleoecology of an Upper Ordovician submarine cave-dwelling bryozoan fauna and its exposed equivalents in northern Kentucky, USA

It is work Caroline Buttler (Head of Palaeontology at the National Museum Wales, Cardiff) and I pursued as our first joint project. An early version is described in this blog post. Thank you to Caroline for her leadership, and the Luce Fund at The College of Wooster for its support. If you want a pdf of the paper, just send me an email note.

[I just noticed this is my 1000th post on this blog!]

Delightful fossils in the Middle Jurassic Carmel Formation on my last field day

April 19th, 2018

St. George, Utah — Today I met Jerry Harris, Professor of Geology at Dixie State University in St. George. He was very friendly, generous and knowledgeable, guiding me to two fantastic Carmel outcrops I would not have approached on my own. Shown above is one complete section of the Carmel Formation in the Dammeron Valley. The reddish rocks in the lower right are the underlying Temple Cap Formation; the top of the ridge is the end of the Carmel here — it is unconformably overlain by the Iron Springs Formation (Upper Cretaceous). This is an extensive exposure perfect for exploring.

The red unit here in the Dammeron section is the top of the Temple Cap Formation. I’m not sure if the Carmel commences with the green marls, but classic Carmel limestone is found immediately above.

A curious unit within the lower few meters of the Carmel is this bedded gypsum deposit. It represents a significant accumulation of evaporite minerals, and thus the evaporation of a lot of seawater in an enclosed basin.

The Carmel limestones show normal (but restricted) seawater and lots of evidence of high energy. These carbonate crossbeds are almost herringbone.

This is a view west from the top of the Dammeron Valley section. In the distant left you can see the familiar Square Top Mountain and pointy Jackson Peak. On the right is the majestic Veyo Volcano. The Gunlock exposures are just a few kilometers away, but no outcrops connect them to the Dammeron Valley.

Jerry Harris also showed me large exposures of the Carmel Formation in Diamond Valley, a few kilometers south of the Dammeron Valley location. It is not picturesque, but there is plenty of Carmel under that sagebrush. The excavation for that water tower turned out to be especially good for shelly fossils, so Jerry took me there right way.

The most common fossil is the pectenid bivalve Camptonectes. It has calcitic valves, so they are well preserved, unlike the numerous aragonite-shelled mollusks in the Carmel that are seen only as ghostly molds.

To my delight, some of the bivalves at this locality are encrusted by small cyclostome bryozoan colonies. Jurassic bryozoans are very rare in North America. In fact, Paul Taylor and I have described most of them from the Carmel! (Taylor, P.D. and Wilson, M.A. 1999. Middle Jurassic bryozoans from the Carmel Formation of southwestern Utah. Journal of Paleontology 73: 816-830.) The exquisite bryozoan colonies above are as good as any we’ve found before. A thorough study of all the Carmel sclerobionts is worth pursuing.

There are also nice wedge-shaped limid bivalves at the water tank exposure in Diamond Valley.

These fossiliferous slabs have lots of treasures. I only wish they were more common in the Carmel.

Here’s a simple Google Maps image of my three main areas of study north of St. George. 1 = Gunlock, 2 = Dammeron Valley, 3 = Diamond Valley. Curiously, the most fossiliferous part of the Carmel Formation (the upper unit of the Co-op Creek Limestone Member) differs significantly between Gunlock on the west and the two valleys on the east, even though they are only a few kilometers apart. The Gunlock area has oyster balls and hardgrounds, which are absent in the east. The trace fossils are also more abundant and diverse in Gunlock than in the other two sections. Shelly fossils, though, appear to be more common in the east. It will be fun to sort out these facies differences in more detail.

Finally, I wanted to include an image of the cinder cone and lava flows at the entrance to Diamond Valley. They are within Snow Canyon State Park and have been dated at an astonishingly young age of 32,000 years.

Great day, great scouting trip. Thanks again to Jerry Harris and Andrew Milner!

Another day in the shallow Jurassic seas of southwestern Utah

April 18th, 2018

St. George, Utah — Back to the Gunlock region for me to revisit old Carmel Formation research sites to check for access issues and new exposures. This trip has also given me a chance to update my images of the unit. Most of my previous images are shockingly on film. I’ve been in this business a long time.

Above is one of my favorite Carmel outcrops, the cliff at Eagle Mountain. The white and buff layers are the Co-op Creek Limestone Member of the Carmel Formation (Middle Jurassic). They are topped by a thick, well-cemented conglomeratic sandstone, The Iron Springs Formation (Upper Cretaceous). This is a nice example of an erosional disconformity between the units with an interval of time unrecorded (a hiatus). The cliff is on private land, so I’m in the process of finding the owners. The image was taken looking northeast from: 37°18.428’N, 113°44.408’W.

Today I looked at some smaller details in the Carmel sections. I found these exquisite mudcracks near the Eagle Mountain locality. This is solid rock, even though the cracks look modern. This shows, of course, that this patch of muddy seafloor dried out, producing the cracks by desiccation of clay minerals.

On top of the mudcracked layer is a thin carbonate bed with vugs and cracks filled with gypsum. This represents a hypersaline environment where gypsum and/or anhydrite was precipitated as evaporite minerals. We thus went in time from a dry seabed to one covered by shallow briny water.

Within the gypsum-rich layers are intraclasts of carbonate mud derived from the mudcracked layer below. When the seawater returned it had enough energy at times to rip up pieces of the hardened mud below.

Finally, on top of the gypsiferous layer is a limestone rich in star-shaped crinoid debris (ossicles of Isocrinus nicoletti). This represents the influx of normal marine water, albeit in a restricted context. As far as I can tell, there are multiple triplet layer sets like this near the middle of the Carmel in the Gunlock area. What was controlling these changes in sealevel and chemistry?

I would be neglecting my duties as a geologist if I didn’t mention that there is much more to the geology here than the Carmel Formation. Above we see the underlying Navajo Sandstone with its massive cross-bedded eolian dune features. The Navajo is topped here by thick basaltic lava flows of Pleistocene-Holocene age (the Santa Clara Volcanic Field).

Lovely place for a geologist!

Another geological scouting day in southwestern Utah

April 17th, 2018

Kanab, Utah — My day began with a visit to the St. George Dinosaur Discovery Site at Johnson Farm, where I met Andrew R.C. Milner, the Site Paleontologist and Curator. This museum is built over an extraordinary set of dinosaur trackways. These tracks were not even discovered when I started working in the area, and now this building houses a busy and productive center for vertebrate paleontology in the region.

Andrew is a dinosaur paleontologist and an expert on vertebrate trace fossils, and he also knows a lot about the Carmel Formation and its outcrops in Utah. He gave me local contacts, and will join us in the field when we start the official Utah Jurassic expedition next month. He has been very helpful.

I then drove to Mt. Carmel Junction on the eastern side of Zion National Park, about two hours from St. George. It is a small place with a surprisingly long Wikipedia page. It sits in the center of several extensive exposures of the Carmel Formation, including this cross-bedded unit made almost entirely of crinoid ossicles. These rocks are called encrinites. This particular Middle Jurassic encrinite is one of the youngest known. This exposure is at Stop #5 of Tang (1997). It is still easily accessible at the northwest corner of the junction.

Alas, this great expanse of Carmel Formation, known as Stop #6 in Tang (1997) is no longer accessible, at least not easily. If you look carefully you can see a barbed-wire fence at the base of the outcrop. I could find no evidence of who owns this land, and jumping a fence out here can have serious consequences! Unfortunately there are far more such fences here than were present in the easy-going 1990’s. This makes taking students here harder for casual examinations of the rocks.

I spent the night in nearby Kanab, Utah, where I got to spend excellent time with my Father, who was in the area hiking with two friends. I then drove back to St. George the next morning, passing through a long stretch of northern Arizona. This included driving by the storied Colorado City of FLDS fame. Follow those links if you don’t know the story!

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