AMRE Summer 2020 – Remote Learning and Tree Rings – Part 1. The Oaks at the Kinney Soccer Fields, Wooster, Ohio

By: Mazvita Chikomo, Srushti Chaudhari, Fred Zhao (as part of the AMRE 2020; The College of Wooster, Tree Ring Lab)

The aim of this study was to analyze White oak trees, to see how old they are and, how they are responding to the wetter and warming climate in Wooster, OH.

Kinney Field, Wooster, OH.

The AMRE_Tree Ring Team 2020 is pictured above.

Kinney Field, located in Wooster, OH has long served as a recreational location for various sports and a nice place for public entertainment. On its southwest corner are several old white oaks making it an ideal destination for tree-ring research. The geological setting is an Ice Age kame (hill) left by the retreating Laurentide Ice Sheet approximately 15,000 years ago.  The hill on which the trees grow is thus a well-drained feature built of permeable sediments, likely sand and gravel. We set out to determine the age of the trees, build a tree-ring chronology from the ring-widths, and compare the ring-width series with the monthly meteorological observations recorded at Wooster’s OARDC since C.E. 1888. This helps us better understand how this important tree species is reacting to a changing climate.

Bottom line: Nineteen cores were taken from 11 trees and processed at The College of Wooster Tree Ring Lab. We found that the White Oaks (Quercus alba) growing in the Kinney Field are positively correlated with precipitation in the April, May, June, and July months and have a strong negative correlation with June temperature.

Methods: Nineteen 5-mm diameter tree cores from were collected from 11 trees (Table 1) and, combined to produce a ring-width tree-ring chronology (Figure 2) at the Kinney Fields site, in Wooster, OH (Figure 1). The samples were cross dated in The College of Wooster Tree Ring Laboratory (WTRL) and were measured to the nearest 0.001 mm. This was then statistically cross-dated using the COFECHA (Holmes, 1983) software, and the chronology was then standardized using the ARSTAN software (Cook et al. 1985). The final chronology is made up of 19 cores from 11 trees with a mean series intercorrelation of 0.66 and an average mean sensitivity of 0.24 (Table 2). We used the raw data for the final chronology and point out the upward increasing trend in the series (Figure 2).

Fig. 1: Map showing study site at Kinney Field, Wooster, OH. 

The monthly temperature (1894 to 2019) and precipitation (1888 to 2019) for Wooster Ohio taken at the OARDC data was acquired from the Global Historical Climatology Network (GHCN). The mean annual temperature was 9.8ºC and the average annual precipitation was 947 mm during this time period. The months with the highest precipitation for 1888 to 2019 were June and July, and the highest temperature during the years 1894 to 2019 were June, July, and August. The months with the lowest temperatures were January and February (Figure 3).

The team coring a White Oak.

Measuring tree cores from Kinney Field in the Lab.

Fig. 2: The raw ring width series for the Oaks at Kinney Field, Wooster, OH.

Fig. 3: Climograph showing the annual distribution of precipitation (1888 to 2019) and mean monthly temperature (1894 to 2019) for Wooster.

Fig. 4: Raw ring-widths correlated with monthly temperature records. Only the month of June is significant at the 0.05 level (the common interval is 1895-2019).

Fig. 5: Raw ring-width series correlated with monthly precipitation (1888-2019). The months of April-July are significant (p<0.05) and positive correlations.

Fig. 6: April-July total precipitation correlated with the raw ring width series with a correlation 0.57.

Discussion: The final ring width chronology is 200 years long from 1820 to 2019. The series intercorrelation is 0.66 whereas the mean sensitivity (measure of year to year variability) is 0.24. The series autocorrelation is 0.60 and is a measure of the persistence as it is when the chronology is correlated with itself. The mean ring width measurement is 4.25 mm, which is significantly high relative to other sites and implies that the trees have proper access to nutrients and there is little competition.  There is a strong positive correlation between the ring width and the precipitation in the months of April through July, and the trendlines for both closely follow each other throughout the chronology ( Figures 5, 6). Therefore, we can gather that the trees are tracking the low frequency increase (last ~100 year rise) in precipitation of the region and are also a good indicator of year to year April – July precipitation records in Wooster, OH. The correlation with monthly temperatures is only significantly negatively correlated with June temperature (Figure 4).  The correlation with June is -0.35 (Figure 5) is likely attributed to the high rates of evapotranspiration in the summer months, which can have negative impact on tree growth.

Conclusions:
1. The Kinney oaks are all less than about 200 years old and are therefore likely second growth;
2. The raw ring-width data from 19 tree cores has an upward trend strongly correlated with total April through July precipitation measured at the OARDC since 1888;
3. The negative correlation of -0.35 of raw ring width and June temperature is due to increased evapotranspiration demand during warm Junes.

Acknowledgements:
This work is supported by the Sherman-Fairchild Foundation and the Luce Foundation. We also thank the organizers of AMRE 2020. A special thanks to Melita Wiles for doing all the measuring, Pedro Oliboni for coring the trees and his help with R, and Corinne Wiles for making the blog entry. All three students worked on this project because they lived in the relocated Wooster Tree Ring Lab during the Summer of 2020. Thanks also to the organizers and directors of AMRE.

 

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New Paper on the Dawn Redwood (Metasequoia) Trees of Wooster Ohio

The Wooster Tree Ring Lab has just published a paper with Franklin and Marshall College and The Ohio State University on the climate response of the Dawn Redwood tree. The study site is the beautiful Secrest Arboretum at the OARDC – OSU Wooster Campus. The upshot is that these remarkable and fast-growing trees are clearly doing well and as long as the increase in precipitation that Northeast Ohio is receiving keeps pace with the summer warming they should continue to do well. Why not plant more of these beautiful trees as they thrive, sequester carbon, and provide many other ecosystem services.

The senior author is Lauren Vargo, who is now a glaciologist research scientist at the Antarctic Research Centre in Wellington, Australia. Lauren did much of this work while an undergraduate at Wooster. Lauren is also the recent lead author on this Nature Climate Change contribution. Great thanks to Lauren also for sharing here research this summer.

Here is the technical abstract of the Dawn Redwood paper:

ABSTRACT

Metasequoia glyptostroboides,a deciduous gymnosperm, also known as dawn redwood, was thought to be extinct until living members of the species were found in China in 1943. Analyzing the climate response of a transplanted stand of the trees can give insights into their physiological plasticity, into their use in restoration and reforestation, as well as into interpreting the environmental conditions of the geologic past from fossil Metasequoia. An annual ring-width chronology—spanning 1955 to 2010 and based on a stand of 19 M. glyptostroboides trees planted in Secrest Arboretum in northeast Ohio, USA—shows negative correlations with maximum monthly temperatures: with the strongest relationship with February and the warm months of June and July, all significant at the 99% confidence levels. A positive May to June precipitation correlation is the strongest moisture signal (p < 0.05) and the narrowest rings in the chronology occurred during the drought of 1987 to 1988, consistent with one of the warmest and driest Junes on record. These results have implications for the future as climate change affects the native and transplanted range of this species. Future response of this species to a changing climate will depend on the relative rates of warming maximum temperatures in the winter and summer, as well as changing moisture conditions during the summer months.

Figure above shows the tree-ring record from a stand of 19 Dawn Redwood trees (upper panel A). The lower blue and red graph (B) is the climate response of the trees – temperature (red bars) is strongly negatively correlated with summer (June and July) temperatures and with February temperature. The summer relationship makes sense as hot summers require higher evapotranspiration demands. The negative correlation with winter is hypothesized to be linked to warming winters leading to less snow cover leaving roots exposed and vulnerable to damaging frosts. This negative relationship may go away as warming continues and frosts become less frequent.

Figure above shows three photos of cores from Dawn Redwood – note the narrow 1988 drought ring (white dots). 

The College of Wooster Paleoclimate class mulls around the Dawn Redwood stand. 

Another great photo of  Dawn Redwoods – they are deciduous conifers so this photo in the early spring before growth.

Many thanks to the Secrest Arboretum for permission to core these impressive trees. We greatly appreciate the support of Jason Veil the Curator of the Arboretum.

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New paper on a symbiotic relationship between tube-dwellers and bryozoans in the Silurian of Estonia

I have thoroughly enjoyed my many expeditions to the wondrous Baltic country of Estonia. My Estonian colleagues are fabulous, and I’ve been privileged to share the adventures with numerous students and Bill Ausich of Ohio State. Now during this global pandemic Estonia may as well be on the far side of the Moon. Maybe someday in the New Normal such travel will be possible again.

In the meantime, Olev Vinn has led our small international team to a new paper published today in the journal Lethaia. It is part of a long-term project describing the evolution of symbiosis among marine invertebrates. The abstract follows —

AbstractCornulites sp. and Fistulipora przhidolensis formed a symbiotic association in the Pridoli (latest Silurian) of Saaremaa Island, Estonia. This Cornulites sp.–F. przhidolensis association is the youngest example of cornulitid–bryozoan symbiosis. Symbiosis is indicated by intergrowth of both organisms. The cornulitids are completely embedded within the cystoporate bryozoan colony, leaving only their apertures free on the growth surface of the bryozoan. In terms of food competition, this association could have been slightly harmful to F. przhidolensis as Cornulites sp. may have been a kleptoparasite. There may have been a small escalation in the evolution of the endobiotic life mode of cornulitids as the number of such associations increased from the Ordovician to Silurian. It is likely that Palaeozoic bryozoan symbiosis reached its maximum in the Late Ordovician. Most of the symbiotic bryozoans in the Palaeozoic are trepostomes, and the diversity of symbiotic associations was also greatest among trepostomes.

The image above is Figure 2 from the paper. Caption: Cornulites sp. intergrown with Fistulipora przhidolensis from the lower Pridoli (Kaugatuma Formation) of Lõo cliff, Saaremaa, Estonia (GIT 666‐38). A, detailed view of bryozoan, B, Cornulites sp. [Corn] in cross section, C, D, apertures of Cornulites sp. [Corn] on the growth surface of Fistulipora.

If anyone wants a pdf, just send me an email.

Reference:

Vinn, O., Ernst, A., Wilson, M.A. and Toom, U. 2020. Symbiosis of cornulitids with the cystoporate bryozoan Fistulipora in the Pridoli of Saaremaa, Estonia. Lethaia (https:// doi.org/10.1111/let.12385).

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Let’s celebrate Earth Day!

Happy Earth Day, everyone! Although we can’t all be together this Earth Day, we’re still celebrating wherever we are. We hope you’ll join us in celebrating, too. Check out the video below, which tells you what some of our students and faculty are doing!

 

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New Paper on Antarctic Storm Wave Generation

I was part of a team led by Momme Hell at Scripps Institution for Oceanography that recently published an article in the Journal of Geophysical Research Oceans entitled: “Estimating Southern Ocean Storm Positions With Seismic Observations”. Momme is an expert in detecting seismic waves. We often hear about seismic waves in relation to earthquakes, but on an ice shelf (which is floating on the ocean), the surface also moves up and down with ocean waves.

The reason why Momme brought me on this project was because: 1) storm events are an important generation mechanism for these waves, and 2) I developed an algorithm for detecting and tracking storms from atmospheric data (i.e., atmospheric reanalyses). We wanted to know how well the storms detected from the atmospheric renalsyses aligned with the seismic observations that Momme makes.

The tracks of 2827 storms used in this study. These are on the Pacific-side of Antarctica — including the Ross, Amundsen, and Bellingshausen Seas. Many of the same storms passed by Thwaites and Dotson, Ice Shelves, where Dr. Alley was in Nov 2019 – Jan 2020.

The answer? Not nearly as well as we’d like. Only about 45% of the observations in the reanalyses and seismics align with each other. Some of that error is  from the imperfect relationship between seismic observations and wave-generation by storms, but another reason for error is our imperfect satellite observations of storm systems. The Southern Ocean has some of the sparsest atmospheric observations in the world, and the presence of ample sea ice complicates detection. For example, it’s difficult to distinguish between ice crystals in clouds and the snow/sea ice surface below. In other words, NOAA and NASA and other agencies still have some work to do to perfect the science of weather observation.

An example of how seismic stations on the edge of the Ross Ice Shelf were used to detect the location of maximum wind propagation (orange line and red arrow), and how that compared to the storm track in the reanalysis data (black track with gray point as best match). Winds are typically strongest near but not at the very center of a storm, so this is an example of an ideal match. The dark gray blotch at the bottom is Antartica, and the lighter gray around it is the sea ice. The blue is wave heights (darker blue = bigger waves.)


Here is the plain language summary:
“Surface winds under storms over the Southern Ocean make large ocean waves that travel over long distances (>1,000 km). Regions of wave generation coincide with regions where ocean uptake of heat and CO2 is large, so knowledge about wave generation regions helps us to understand the role of the Southern Ocean in the climate system. A 2‐year field campaign made new observations of ocean wave arrivals at the Ross Ice Shelf. These observations are used to trace the origins of the wave events in the Southern Ocean. Even though the waves observed in the sea ice are much smaller than in the open ocean, the observations are good enough to identify ocean waves. The wave arrivals can be used to infer a most likely time and location of the storm that generated the waves. Comparison with two reanalysis products (Modern‐Era Retrospective Analysis for Research and Applications, Version 2, and ERA5) suggests that more than half of the observed ocean wave events cannot be matched to individual Southern Ocean storms. This high percentage of displaced storms in the reanalysis products can be explained by the limited availability of satellite observations caused by the presence of sea ice.”

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The complex origin of ooids in the Middle Jurassic Carmel Formation of southwestern Utah: Anna Cooke’s Senior Independent Study thesis

Editor’s Note: Independent Study (IS) at The College of Wooster is a three-course series required of every student before graduation. Earth Sciences students typically begin in the second semester of their junior years with project identification, literature review, and a thesis essentially setting out the hypotheses and parameters of the work. Most students do fieldwork or lab work to collect data, and then spend their senior years finishing extensive Senior I.S. theses. This year we have the COVID-19 pandemic to deal with in the spring, so our students have not had a chance to publicly present their hard work and scientific ideas. Some, then, will be writing blog posts like this. The text and images here are from Anna Cooke (’20) who is a member of Team Utah 2019. The picture above shows Anna and fellow team member Evan Shadbolt (’20) on the top of Angel’s Landing in Zion National Park. (Photo by Nick Wiesenberg.) Now Anna takes over —

The Carmel Formation (shown above) formed in a shallow inland sea during the Middle Jurassic and is located in parts of Utah and Arizona. It can be broken into four distinct members, one of which, the Co-op Creek Limestone Member, contains ooid shoals. The ooids in these shoals are calcitic with radial crystals and sparry cement. Several noteworthy features are found in the Carmel ooids, such as delamination, pressure solution, and microborings created by the cyanobacteria: Hyella sp. and/or Solentia sp. Foraminifera are sometimes incorporated into ooids as their nuclei. Seventeen of 21 Carmel thin sections contain foraminiferans inside or outside of ooids. Of these 17, 16 thin sections (94%) show more foraminiferans inside ooids than outside, meaning that ooids can act as taphonomic engineers, preserving what might otherwise not be preserved in the rock record. These foraminiferans likely belong to genera Turrispirulina and/or Ammodiscus. Eolian quartz silt is common in the Carmel shoals. The hypothesis of this study is that a pulse of quartz silt provided nuclei for the formation of the shoals and extinction of the shoals occurred when another pulse smothered it. This is partially supported by point counts, used to determine the percentage of each individual component of these limestones, and nuclei counts, used to determine the percentage of each type of nucleus found in these ooids. The locality that supports this hypothesis most strongly is C/W 142 EMR, which shows three distinct pulses of quartz accompanied by an inverse effect on the percentage of quartz nuclei. Locality C/W 757 DV is also of note, displaying a large amount of quartz early in the shoal’s life, decreasing over time. The percentage of ooids in the shoal shows the inverse. However, other shoals show no such pattern; one method of formation cannot be attributed to all of the Carmel Formation’s shoals, and even those geographically close show marked differences.

Cross-bedded ooid shoal deposit in the Carmel Formation.

Ooids in unit C/W-758A.

I have nothing but positive things to say about my I.S. experience at Wooster. Over the last three semesters, I have had the privilege of researching the Carmel, a formation in southwestern Utah that several other students have done research in. My focus was on ooids: tiny spherical grains composed of calcium carbonate which form in specific marine environments. I have learned so much about these amazing little grains, though at times they made me want to tear my hair out (I personally marked, counted, and recorded the nuclei of over 17,000 ooids)! Though I.S. is a process that comes with a certain amount of stress and frustration, it was also a rich and rewarding experience for me. I learned so much about geology, as well as fieldwork methods and research, writing, and presentation skills. My favorite part of this experience was the field work, which I conducted the spring semester of my junior year with the help of the rest of Team Utah 2019. I am so grateful to everyone who has helped me along in this process, especially my wonderful advisor Dr. Wilson! Independent Study is something I will no doubt remember fondly for the rest of my life!

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Coryphodon and the Paleocene-Eocene Thermal Maximum: Emily Randall’s Senior Independent Study thesis

Editor’s Note: Independent Study (IS) at The College of Wooster is a three-course series required of every student before graduation. Earth Sciences students typically begin in the second semester of their junior years with project identification, literature review, and a thesis essentially setting out the hypotheses and parameters of the work. Most students do fieldwork or labwork to collect data, and then spend their senior years finishing extensive Senior I.S. theses. This year we have the COVID-19 pandemic to deal with in the spring, so our students have not had a chance to publicly present their hard work and scientific ideas. Some, then, will be writing blog posts like this. The text and images below are from Emily Randall (’20) who participated in a Keck Geology Consortium project last summer. The picture above shows Emily on the right in Wyoming (with Isaac and Mike) collecting Coryphodon teeth. And now Emily takes over —

Abstract

Preliminary data point toward a new hypothesis in which Coryphodon lived in wetter habitats before the Paleocene-Eocene Thermal Maximum (PETM), but was able to adapt to drier habitats in order to survive post-PETM. Early Paleogene nonmarine strata are extensively exposed in the Bighorn Basin of northwestern Wyoming. The Fort Union and Willwood Formations represent alluvial deposition within a Laramide Basin formed from the Paleocene through early Eocene. Therefore, the basin is an ideal place to study the local effects of the PETM, a rapid global warming event that occurred about 55.5 million years ago at the Paleocene–Eocene boundary. During this event, an initial decrease in rainfall was followed by wet and dry cycles with increased temperature and decreased precipitation. Some flora and fauna went extinct, but many others exhibited dwarfing during this interval. The response of the large mammal Coryphodon to the PETM is poorly understood, but is of special interest due to its inferred semiaquatic nature.

We collected 14 stratigraphic sections from 5 mammalian biozones within the Bighorn Basin, each centered around depositional units containing Coryphodon. The depositional environments of these units were evaluated by describing the grain size; matrix and mottling colors; mottling percent; abundance and type of nodules; shrink-swell features such as slickensides and clay cutans; and other interesting attributes such as organic matter, invertebrate fossils, sedimentary features, and mottling color or percentage stratigraphic changes. The depositional environments include ponds, swamps, fluvial deposits, soils with evidence of wet and dry cycles, and dry soils.

 

Reflection

Completing my independent study was an extremely rewarding process and I am so happy I was able to have this experience. I was lucky enough to be part of a larger Keck Geology Consortium project, which allowed the team to tackle many more research questions than just one student project ever could. We spent about a month in the Bighorn Basin in northwestern Wyoming collecting data over the summer before I began working on my independent study on campus. It was amazing to be able to gain so much field experience and get to work with such a great team! Back on campus, I was able to focus on data analysis and teaching myself Adobe Illustrator in order to create stratigraphic columns. And then, of course, there was a lot of writing, reading, thinking, and analysis to do to complete my independent study. In the end, I am very proud of how my stratigraphic columns and independent study turned out!

Stratigraphic columns from Clarkforkian (Cf) 2 and 3 mammalian biozones (Pre-PETM).

Some of the Keck Wyoming team collecting Coryphodon fossils. From top to bottom left and then top to bottom right, Michael, Richard, Grant, Simone, Danika, Isaac, and Emily.

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Jurassic bivalves in a shallow epicontinental seaway: Evan Shadbolt’s Senior Independent Study thesis

Editor’s Note: Independent Study (IS) at The College of Wooster is a three-course series required of every student before graduation. Earth Sciences students typically begin in the second semester of their junior years with project identification, literature review, and a thesis essentially setting out the hypotheses and parameters of the work. Most students do fieldwork or labwork to collect data, and then spend their senior years finishing extensive Senior I.S. theses. This year we have the COVID-19 pandemic to deal with in the spring, so our students have not had a chance to publicly present their hard work and scientific ideas. Some, then, will be writing blog posts like this. The text and images below are from Evan Shadbolt (’20) who worked with me on Team Utah 2019. The picture above shows Anna Cooke (’20), Evan Shadbolt (’20) and me at an outcrop of the Carmel Formation (Middle Jurassic) near Gunlock, Utah, in March 2019. And now Evan takes over —

The Jurassic bivalves Plagiostoma ziona (right) and Camptonectes stygius (left).

The Carmel Formation of the Middle Jurassic has many mysteries. One of these enigmas is its bivalves. The formation contains the famous oyster balls called ostreoliths. Despite bivalves making up 80 percent of the fossils found in the Carmel Formation, it is not understood how the bivalves lived in this community. The formation is located in southwestern and central Utah. It was deposited when an epicontinental seaway covered most of Utah. The paleoclimate of Utah was hot and dry, which meant that the environment was evaporite heavy. This also meant that the seawater at the southernmost extent of the seaway in Utah was hypersaline. The bivalves lived in normal marine conditions, but there was little biological diversity. During the Jurassic, there was a calcite sea, and aragonite shells were dissolved away.

In mid-March 2019, I went with a College of Wooster group to southwestern Utah. There we collected bivalves from the Carmel Formation and identified them. Then we researched them and constructed a systematic paleontological overview of the known bivalves. We have possibly identified ten different types of bivalves, and three distinct communities in the Co-op Creek Limestone Member of the Carmel Formation. The communities were the Plagiostoma community, Camptonectes community, and the Liostrea Community. Each of these communities was dominated by a unique bivalve. The Liostrea community was associated with hardgrounds, while the Camptonectes and Plagiostoma communities lived in the same type of environment. We also hypothesize that the area was frequently hit by storms, which caused damage to these communities. The communities were possibly ephemeral, but the bivalves themselves could be considered opportunists. The communities in the Carmel Formation were also small and patchy throughout the area. The bivalve genera that appeared in the Carmel Formation were common in other Jurassic bivalve communities around the world.

My IS experience was fun and unique. Getting to travel to Utah and collect fossils with Team Utah 2019 was a rewarding experience. We spent a week there exploring the Utah environment. Luckily, I was able to collect my fossils over the spring break of my Junior year, so I could start my research early. I felt I was well prepared to start my IS, thanks to the help of the Team Utah 2018 and my advisor, Dr. Wilson. The IS writing experience was not as stressful as I thought it would be. The deadlines were all reasonable and even if I felt I did not do enough work that week, Dr. Wilson was always fine with the amount of work. I feel that the Earth Sciences department at The College of Wooster properly prepare you for writing your IS.

A reconstruction of the bivalve community sampled at Water Tank.

A reconstruction of the bivalve community sampled at Eagle Mountain Ranch.

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Wooster’s Team Utah 2020 Fieldwork

This is the index page for Wooster’s Team Utah 2020 expedition (March 9-13, 2020). The team members above are, from the left, Will Santella (’21), Juda Culp (’21), Nick Wiesenberg (geological technician), and Dr. Shelley Judge (structural geologist and tectonicist). Plus me, of course, Wooster’s sedimentologist and paleontologist. The Pine Valley Mountains are in the background.

This stratigraphic column from the National Park Service details the stratigraphy of southwestern Utah. Our expedition was to continue long-term Wooster explorations of the Carmel Formation (Middle Jurassic) near the top (marked with the red dot). We are preceded by several teams in the 1990s and most recently by Team Utah 2018 and Team Utah 2019. I am a most fortunate professor and geologist to work with such fine people in such a beautiful, stimulating place.

Here are the links to our daily field posts —

March 10: Field geology in a time of plague
March 11: On a Jurassic tidal flat
March 12: Final day in the field (alas)

I hope you enjoy these descriptions and images.

ADDENDUM on March 19, 2020 — Boxes of samples safely arrived in Wooater!

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Wooster’s Team Utah 2020: Final Day in the Field (Alas)

Hurricane, Utah — Last night we made the sad decision to leave for home as soon as possible because of the COVID-19 pandemic. The College has mandated no more in-person teaching, and we don’t want our flight plans to be complicated by cancellations and other mass-transit issues. This is thus our last day in the field.

We started at our treasured oyster-ball locality in Manganese Wash just north of the Gunlock Reservoir (C/W-157; field code MW). This was a key site for Team Utah 2018, but we could not access it last year because the bridge over the Santa Clara River had washed out. The bridge is back so over it we went. This is now Juda’s second site for trace fossils in the upper part of the Co-op Creek Limestone Member of the Carmel Formation. As you can see in the image above with Dr. Judge, there is more brush and weathering at this location than at Eagle Mountain Ranch. This made the trace fossils less crisp in their preservation.

This diffuse set of traces is new to us. It seems to be a deposit-feeding swirl.

Herringbone cross-stratification in this location as well. The paleoenvironment is still shallow and normal marine.

While Juda, Dr. Judge and I worked in the upper Co-op Creek, Will and Nick climbed up a ridge and then down towards the Gunlock Reservoir to visit the lower Co-op Creek and its stromatolites. They again measured, described and collected the unit.

And that was it for our fieldwork! We shipped three heavy boxes of samples back to our Wooster lab. We met our field goals, despite the truncated schedule.

To celebrate, we had another round of Veyo pies and then visited Snow Canyon State Park north of St. George. The Jurassic Navajo Sandstone is weathered in three dimensions here, enabling us to scramble about on its “petrified dunes”. Such a beautiful mix of orange white and black rocks with the green plants and blue skies.

Needless to say, Juda and Will liked the place.

The Jurassic dunes here have deeply eroded foresets at sometimes surprisingly steep angles.

Team Utah 2020! Plus Nick, who took this image. Such a fine crew in skills and enthusiasm.

(Links to the First Day, Second Day, and Third Day.)

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