Post by: Maya Gangishetti, Cooper Dawson, Alice Goldstein

GPS Coordinates: +44.043985, -123.077119

Location of Google Earth

Location and general description: This statue sits outside the southwest corner of the Jordan Schnitzer Museum of Art on the University of Oregon’s campus. Originally created by John Geise and donated by the William A. Haseltine family, this statue honors Karl Onthank, an administrator on campus known for his dedication to the University of Oregon (University of Oregon, 2020). This statue is of three people hugging and displays the aging and weathering of the stone as it grows moss.

Geological observations: The Family Group is composed of an unknown rock or stone, and it depicts four people hugging. It is approximately 6.5 feet tall and 3 feet wide. The statue appears to originally have been off-white in color, but has since weathered to a gray, with some areas being significantly darker than others. Some lighter, textured spots are visible, typically between 1-3 cm in size. Some sort of moss or lichen is visibly growing on the stone. 

Figure 1: The Family Group statue sits outside the JSMA (pictured with 20 cm scale for reference)

 

Resilience in the face of Moss: What geological conditions support moss life, and how might this moss impact The Family Group statue?

Contributed by: Maya Gangishetti

What drew me to this statue was not its shape or form, but rather its unique portrayal of “family love”. The Family Group statue is a beautiful display of family love and resilience as the statue is clearly weathered and covered in white stains and moss. These stains and growths are what make the statue interesting, perhaps unintentionally conveying a message of resilience and strength in its deterioration. Because of this, my question is focused on the moss. Does it strengthen or weaken The Family Group? What geological conditions support moss life, and how might this moss impact The Family Group statue? Is it possible that the statue was sculpted to be grown over? 

Description of scientific article: To answer this question I read about an experiment conducted to understand “moisture interactions” between mosses and substrates like limestone and cementitious stone beneath them, as researched by Jang and Viles (2021). Jang and Viles (2021) used a series of non-invasive tests on various substrates, (or underlying layers), in different conditions, monitoring the moss and the relative humidity, or RH. Measuring it as a percentage, they found that moss prefers a higher RH%, with more consistent temperature and rainfall (Jang and Viles, 2021). I chose this article because I knew that the work done by Jang and Viles (2021) would go into depth about the possible effects of moss on its underlying substrates. In the end, they found that removing moss could actually be more destructive to the stone than leaving it! A factor I find to be particularly interesting when considering art pieces like The Family Group. It makes me wonder if some features are made with materials that are meant to be grown over, such as moss.

Intersection between peer review and research observations on campus: There is a significant intersection between the article by Jang and Viles (2021) and The Family Group, mainly when considering the positive and negative effects that moss might have on the statue. When inspecting the moss on The Family Group you notice that it grows within the crevices of the statue, where most of the water and moisture would be retained. This supports the research done by Jang and Viles (2021), where they found that moss grows best in higher RH%, with consistent precipitation and temperature (or humidity). Additionally, the research addresses one of my previous questions asking, is it possible that the statue was sculpted with substrates that are able to support moss? If moss can be used in a productive way, protecting the substrates below from the outdoor elements, then maybe The Family Group was designed with moss in mind, protecting the statue from possible acid rain, or rain that is more acidic because of pollution (Jang and Viles, 2021). It’s possible The Family Group was sculpted with materials like limestone or cementitious stone, both of which have the capability to provide the desired conditions for moss to grow (Jang and Viles, 2021). Alternatively, maybe The Family Group wasn’t meant to be grown over, as moss has been shown to retain moisture and ultimately deteriorate the substrates below it (Jang and Viles, 2021). While we can consider either option when examining The Family Group, it would be hard to check its deterioration because we would have to remove the moss from the statue, which could cause unnecessary damage.

 

An answer to the question? My original question asks, what geological conditions support moss life, and how might this moss impact The Family Group statue? The paper written by Jang and Viles (2021) answers my second question in regard to the impact that moss might have on The Family Group. As previously mentioned moss can grow to become a protective layer for its underlying substrates, possibly protecting stone like The Family Group from weathering and environmental factors like acid rain (Jang and Viles, 2021). Moss also has destructive capabilities because of its ability to retain moisture, and as found by Jang and Viles (2021), this moisture retention can cause the substrates to deteriorate, ultimately harming stones like The Family Group statue. While the article by Jang and Viles (2021) went in-depth to answer my question about the possible impacts of moss on the statue, what wasn’t really answered was the possible geological conditions that might support moss growth. Jang and Viles (2021) briefly outline limestone and cementitious stone as the best substrates, additionally explaining that higher RH% and more consistent temperature and rainfall are the preferred conditions for moss to grow.

Something additional you learned and extra questions? Something interesting that was briefly mentioned by Jang and Viles (2021) was that sometimes the relationship between moss and stone is inseparable. It’s easy to consider the two as separate organisms and substrates, but the reality is that no one organism can survive without another or even another organic material like stone. This realization brings me to a new question: can we create art and/or structures that have a symbiotic relationship with nature? In other words, can we design structures that utilize plants, and can we apply plants that utilize structures?

 

 

What Type of Rock is the Statue “The Family Group” Made out of?

Contributed By: Cooper Dawson

Geological Question: The question I chose for this site is asking what type of rock the statue is made out of. This question seemed like an obvious one to ask because even the museum doesn’t know what the statue is made out of. This makes the question interesting as it seems like an important piece of information is missing about this statue. It also relates to the questions asked by my groupmates about the weathering and moss that is present on the statue.

Description of Scientific Article: The article I chose is (McGreevy et al., 1983). I chose this article because our group noticed that the weathering on the statue looks like it could have been caused by acid rain, due to the brighter coloring on the covered areas of the statue. (McGreevy et al., 1983) analyzes the effects of acid rain on certain rocks that contain calcium carbonate, so I thought it would help me possibly connect the acid rain damage to a certain type of rock that the statue could be made out of.

Intersection Between Peer-Reviewed Research and Observations on Campus: (McGreevy et al., 1983) describes the process of how acid rain affects rock that contains calcium carbonate. Our group noticed signs on the statue such as brighter white colors on portions of the statue that would be less exposed to rain, as well as the small divots mentioned in our description of the statue. Both of these can be seen in figure 1. One of the bright white covered areas is directly above the 20 cm scale and some of the divots can be seen at the base of the statue above the plaque. Our group thought that these features could be evidence of acid rain damage. According to (McGreevy et al., 1983), the process of acid rain weathering begins with chemicals such as sulfur being released into the atmosphere by sources such as the burning of fossil fuels by humans. The sulfur then mixes with rain to create acid rain. When acid rain comes down the sulfur reacts aggressively with rocks that contain calcium carbonate such as marble and limestone. The mixing of sulfur and calcium carbonate on the stone creates gypsum. Gypsum has two main features that seem to be present on the statue. The first one is that gypsum traps dirt and grime in it, making the areas of the statue exposed to acid rain become darker. The second feature is that gypsum is prone to flaking off, causing physical damage to the stone. As mentioned in our description of the site, the statue seems darker on the areas that are exposed to rain and has small divots across the rock. Both of these could have been the result of acid rain weathering on the statue.

An Answer to the Question?: (McGreevy et al., 1983) did not necessarily answer my question completely but it gave me a good theory on what the statue could be made out of. Due to the evidence on the statue of what is likely acid rain damage, the statue could be made out of some rock that contains calcium carbonate, or even man-made concrete containing calcium carbonate. To truly know what the statue is made out of, more invasive tests would probably have to be conducted. However, since it is an art piece and is museum property, we have to go off observations alone, which (McGreevy et al., 1983) was helpful in refining.

Something Additional I Learned and Future Questions: Something additional I learned from (McGreevy et al., 1983) is that the formation of gypsum from the reaction between sulfur and calcium carbonate can happen in areas that aren’t directly exposed to rainwater. According to (McGreevy et al., 1983) this happens because moisture that contains sulfur can still condense in unexposed areas. However, it doesn’t look like this happened much at the site because the under-arm areas that are bright white seem clear of gypsum. A future question that I have is what other methods could be used to accurately determine what the statue is made out of. Preferably, what methods could be used that wouldn’t harm the statue, because I doubt the museum would allow the art piece to be damaged.

 

 

What Geological and Meteorological Conditions have Contributed to the Weathering of the Family Group?

Contributed by: Alice Goldstein

Geological Question: My inquiry is into why the ‘family group’ statue has weathered in the way it has, including its change in color over time. I seek to know what geologic and meteorological phenomena have altered the look and stability of the Family Group. As an art piece, the appearance of the Family Group is perhaps its most important virtue. Thus, it seems relevant to investigate why the family group seems to have changed so much since its installation. As the material comprising the statue is unknown, the following will be a more generalized investigation into why buildings and structures wear, mainly focused on environmental contributors (rapidly changing climate, air pollutants, acid rain, etc.). 

Description of scientific article: To learn more about environmental weathering of manmade structures, I read a study from Brimblecombe and Grossi (2007). It seeks to predict and understand how manmade structures will be affected by changes in the climate over the course of the next century. Because so much has changed post-industrialization, this article posits that salt weathering will be an issue for buildings and other construction in the years to come, due to rapid increases and decreases in humidity levels, especially across much of Europe. Temperature is also a factor- as global warming trends continue, it is likely that fewer frosts will occur worldwide, meaning that frost damage to buildings and structures will be less of a threat. Brimblecombe and Grossi (2007) also discusses air pollution, concluding that, with the exception of ozone, the production of all major pollutants responsible for damage to buildings are trending down. This is especially relevant in the case of sulfur oxides, the pollutant largely responsible for acid rain and its destructive effects on manmade structures constructed of calcite-rich stone. 

Intersection between peer-reviewed research and observations on campus: The method of weathering that Brimblecombe and Grossi (2007) see as the most likely to do damage to structures in the future is salt weather. This is defined by physical damage to stones containing salt, such as a loss of material and other aesthetic effects, when these salts crystalize. Relative humidity defines when and how crystallization happens- cycles of relative humidity cause crystallization and dissolution, which stress the material (Brimblecombe and Grossi 2007). As the material of the Family Group is completely unknown, and thus it is impossible to say for sure whether its composition contains salts subject to this kind of weathering. However, the pattern of small indentations or holes in stone material that is characteristic of salt weathering does resemble a slightly more extreme version of the texture of the Family Group. Just as likely, if not more, is that the weathering of the statue was the result of acid rain damage. When sulfur is deposited via acid rain, it reacts with stone containing calcite to form a crust of gypsum. This white mineral blackens over time, permanently discoloring the stone. Brimblecombe and Grossi (2007) identifies a range of blackening that is acceptable to a viewer of a stone building or structure; essentially, blackening past the point of simply darkened shadows is seen as downgraded in aesthetic value. In the case of the Family Group, its ability to be enjoyed as art depends on this perceived aesthetic value, and it is squarely out of the aesthetically acceptable range. 

An answer to the question? In this inquiry, I was not able to discover any one particular cause of the Family Group’s weathering. As mentioned above, temperature, humidity, salt weathering, and more all likely play a role. From previous research (McGreevy et al 1980), I would posit that the most plausible explanation for much of the statue’s aesthetic weathering is acid rain. Brimblecombe and Grossi (2007) do raise an interesting point, however, in explaining that rates of sulfur and nitrous oxides are much less present in the atmosphere than they used to be, meaning acid rain would not be responsible for much damage to the statue within the last handful of years, or going forward. 

Something additional I learned and future questions: I also learned that, unlike other major pollutant groups like nitric oxides and sulfur oxides, atmospheric ozone levels are not trending down in the long term. It has proved harder to reduce tropospheric ozone levels, and they are likely to remain high across large swaths of heavily populated continents (Brimblecombe and Grossi 2007). This introduces another possible source of weathering: ozone (and other oxidants) can cause damage to polymers and organic materials in some modern constructions over time. Given this, what can be done to combat ozone’s effects on constructions like the Family Group? What about this pollutant makes it so uniquely difficult to legislate into control, and what solutions have already been tried? 

Sources Cited: 

Brimblecombe, P., & Grossi, C. M. (2007). Damage to Buildings from Future Climate and Pollution. APT Bulletin: The Journal of Preservation Technology, 38(2/3), 13–18.

Jang, K., & Viles, H. (2022). Moisture Interactions Between Mosses and Their Underlying Stone Substrates. Studies in Conservation, 67(8), 532–544. https://doi.org/10.1080/00393630.2021.1892430

McGreevy, J. P., Smith, B. J., & McAlister, J. (1983). Stone decay in an urban environment: observations from South Belfast. Ulster Journal of Archaeology, 46, 167-171.