Post by: Bray Belloni, Maia Turpen, and Heidi Sunderhaus

Coordinates: 44.04223° N, 123.07563° W

Link to Google Earth Site (site 4)

Location/General Description:

These gravestones are found in the Eugene Pioneer Cemetery in Eugene, Oregon in the United States. The cemetery honors people in Eugene’s history who have passed and is the largest based on size (acres) and number of burials compared to the others in the area. There are a variety of different-sized gravestones and some headstones are made of marble whereas others are composed of granite. After hearing how acid rain, earthquakes, and other geologic hazards can affect nature, we were curious how the effects of climate change would impact rocks like granite and marble. We will investigate and connect these findings to gravestones at the Eugene Pioneer Cemetary.

Geological Observations:

When walking around the cemetery, it’s clear the gravesites are old, but some headstones appear much newer than others. There are two main materials used for the headstones: granite and marble. Observing the granite, it is immediately apparent that it is not affected by rain or air (Figure 1). One granite headstone found had moss growing on it, but none had any sign of weathering from acidic rain. The granite headstones found in the Pioneer Cemetery are composed of quartz, biotite, feldspar, and muscovite. Another interesting variation from one headstone to another is lettering size. On the granite stone shown in Figure 1, the lettering on the date is approximately 28 inches long and 1.5 inches tall. The marble gravestones showed significant signs of weathering, which can be seen in figure 2, where a marble statue has eroded from the top of a gravestone. Marble statues dated similarly to granite ones show much more weathering. Many of the marble gravestones in Pioneer cemetery have a noticeable layer of calcium sulfate (gypsum – a softer rock formed from marble) due to a chemical reaction caused by acidic rain. Because of this, these gravestones have become softer and more porous (contains little holes for air and water to enter), meaning they trap higher quantities of dirt and debris, so they are noticeably more weathered and appear very dark. 

How does the type of soil affect the stability of a gravestone?

Contributed by: Heidi Sunderhaus

Geological Question:

How does the type of soil affect the stability of a gravestone? Soil types include clay, sand, silt, and more. The main difference between these types of granules is their size- sand is the largest, followed by silt, then clay. I am curious if clay is able to stick to itself and be more malleable because the grains are smaller than sand, so it takes less material/energy to move them. In which case, if a gravestone was settled in clay, would it be more stable and less prone to erosion/weathering or movement in the ground from rain? This would affect the headstone’s durability, influencing how well it would preserve and keep its features.

Description of Scientific Article:

I chose Madden et al. (2022) because it sounded like they were going to investigate how metals in varying soil types would affect graveyards. I was interested in how different types of soil could affect the durability of a headstone. Madden et al. (2022) looked heavily into what kinds of metals were found in the soil and found that clay soils retained metals in their top layers and sandy soils allowed deeper penetration of materials like metals. To see what kinds of metals/materials were in the soil, Madden et al. (2022) used Portable X-ray fluorescence (pXRF) which is a non-destructive technique that uses X-rays to determine the chemical composition of a material. I’m curious why the clay soils had more layers closer to the surface. Perhaps, the metals were not able to break through the hard clay. Also, the sandy soils might have been more porous because the grains are bigger, so there is a better chance of other materials seeping in. In relation to gravestones, if the rock is surrounded by porous soil then it is more likely to be contaminated by pollutants in the ground. This could affect the stability of how long the gravestone would be preserved with little weathering/physical damage.

Intersection between peer-reviewed research and observations:

There is heavy rainfall during the majority of the seasons of the year in the Pacific Northwest and I wonder how this contributes to the strength of the soil’s ability to stick together. Figures 1 and 2 both show the dirt and foliage surrounding the gravestones and one can tell that the soil looks very moist from recent rainfall. According to Withrow-Robinson (2024), there is primarily clay soil in Eugene, Oregon. This could factor into how ‘sticky’ the soil is. Clay has very small grains and is (mainly) composed of silicon, aluminum, and oxygen. These elements create a negative charge because clay has a large surface area and is viscous (sticky) so it can hold positively charged ions (a type of atom) like metals (NCDA&CS Agronomic Division, 1999). Due to clay’s ability to absorb metals, I wonder how concentrated the clay soil at the Eugene Pioneer Cemetary is with metals from campus/industrial buildings nearby. For example, wood manufacturing companies like “States Industries” (Key Sectors, n.d.). Madden et al. and references therein (2022) mentioned finding contaminants in the local water in the ground from cemetery materials that were absorbed into the soil and transported by the rain. This could connect when seeing the damage (eg. discoloration of the rock and moss) on the gravestones in the Eugene Pioneer Cemetary. As well as possible metal substances that could contaminate the Willamette River (just a few miles from the Pioneer Cemetery) resulting in harm to wildlife in the river and lowering the overall quality of the flowing water. 

An answer to the question?

Unfortunately, Madden et al. (2022) did not thoroughly look at how different soil types would affect the aging from weathering or erosion on a gravestone. For example, a comparison between a graveyard in Eastern Oregon (desert climate, so dryer and likely has different soil) to a graveyard in Eugene, Oregon (moist environment and clay soil) would show the difference in soil types and how that affects the stability of the gravestones. With this knowledge, I would be able to answer my question better. I thought it was interesting how they concluded that the level of contamination from metals can vary based on the type of soil. Also, they found that graveyards that existed for a longer period of time were more likely to have lead and zinc in them. I’m curious if newer graveyards have a lower concentration of these metals because certain laws from the government have been enacted to lower these air pollutants.

Something additional I learned and future questions:

Madden et al. (2022) mentioned that some graveyards can be reused after a certain amount of time. I didn’t realize that this was a common thing to do and I’m curious if they churn up the ground before putting new gravestones in or if everything decomposes and by the time it would be time to reuse them, the ground is ready for new gravestones. After hearing how there are different types of metal in some clay versus sandy soil, I wonder how the tendency for a gravestone to erode would change in places around the world with contrasting levels of metal contaminants from industrial buildings in the area. Another question I have relates to Table 4 in Madden et al. (2022) because it shows a considerably high concentration of iron found in the clay samples of this study and I wonder what building/industrial factor in that area would lead to this large amount of iron contamination.

References:

Key sectors. (n.d.). Eugene Chamber of Commerce. https://www.eugenechamber.com/key-sectors.html

Madden, C., Pringle, J. K., Jeffery, A. J., Wisniewski, K. D., Heaton, V., Oliver, I. W., Glanville, H., Stimpson, I. G., Dick, H. C., Eeley, M., & Goodwin, J. (2022). Portable X-ray fluorescence (pXRF) analysis of heavy metal contamination in church graveyards with contrasting soil types. Environmental Science and Pollution Research, 29(36), 55278–55292. https://doi.org/10.1007/s11356-022-19676-z

NCDA&CS Agronomic Division. (1999). Clay minerals: Their importance and function in soils. Soil Fertility Note 13.

Withrow-Robinson, B. (2024, June 25). Guide to Oregon county soil survey reports. OSU Extension Service. https://extension.oregonstate.edu/crop-production/field-crops/guide-oregon-county-soil-survey-reports

 

What type of material is ideal for a headstone in the Pacific Northwest given climate change and erosion?  

Contributed by: Maia Turpen 

Context of Geological Question:

There are two different thoughts that came to me that led me to this question. One, not all climates are the same, erosion happens differently depending on the environment it is in. Erosion is the process by which wind, water, or ice wear away and transport materials. Two, gravestones are commonly made of granites or marbles (those were the two we noticed in the Pioneer Cemetery), that are beautiful when installed but whether differently depending on material. With these thoughts in mind, how can someone or their loved one choose a stone that will withstand the climate of the Pacific Northwest (PNW) so that their resting place can be beautiful as long as possible? 

Description of scientific article:

The article I chose explores how cemeteries provide a valuable opportunity for geological studies. I chose this article because of the emphasis it has on accessibility of graveyards as a geologic site and its discussions on weathering effects in graveyards. Gravestones are made from a variety of rock types, including sandstones, limestones, marbles, slates, granites, gabbros, and metamorphic rocks (Metamorphic rocks form underground when rocks are subjected to high heat, high pressure, hot mineral-rich fluids.) like gneisses and migmatites (Morgan, 2016). These stones offer insights into mineral compositions, sedimentary structures (formed when sediments, like organic or mineral particles, accumulate and harden over time), and weathering processes (the breaking down or dissolving of rocks and minerals on Earth’s surface). Gravestones allow geologists to observe rock textures, fossils, and mineral features not easily seen elsewhere. They serve as natural laboratories for studying weathering processes, including the effects of pollution, acid rain, and biological growth. Relatedly, Morgan (2016) explains that gravestones have been used in scientific studies to monitor stone degradation, such as an Oxford University project that examines weathering effects on war grave headstones. Older cemeteries contain locally quarried stones, while Victorian-era and modern cemeteries feature rocks from across the world due to improved transportation (Morgan, 2016). Different rock types weather differently; for example, limestone erodes under acid rain (rainfall made sufficiently acidic by atmospheric pollution that it causes environmental harm), while granite remains durable but less geologically revealing (Morgan, 2016).  

Intersection between peer-reviewed research and observations on campus:

When visiting the graveyard, we learned that acid rain is what deteriorates marble and causes black vertical streaks. These streaks, no matter the age of the marble, made the person’s information much harder to read. This occurs because the marble (CaCO3) reacts with the acidity in the rain (caused by rising greenhouses gases) to create gypsum which is a softer stone and traps dirt. Despite most buildings on campus being LEED certified, there is still lots of pollution that comes with cities. These pollutants (cars, electricity, etc.) contaminate the air and water and lead to acidic rain. So, as our emissions continue, so does acid rain which leads to marble slowly deteriorating. We also learned that because granite does not have the right composition, acid rain does not affect the stone nearly as much. The granite appears clean and is still clearly legible (Figure 1) as there is no chemical reaction with acid rain. Chemical reaction between the different stones and acid rain is what the article discussed. It specified which stones provide ample geological change for study and why that is (Morgan, 2016). In class we classify ourselves as geologists, and the premise of the article was how cemeteries allow geological study, providing convenient access with plenty of data (Morgan, 2016). Cemetaries have been around since humans have, and separate locations, environments, materials, etc., all affect their appearance and overall resilience which allows for ample studies and access for practically anyone.  

An answer to the question:

The article I chose did discuss (indirectly) ideal stones for headstones, some are more prone to weathering than others. The article did not discuss varying climates and the effects they have on the typical headstones which would have been helpful for discovering what is ideal for our region of the United States. Although it did not specify, I can make deductions from the information I have learned in class and in this article. Because the Pacific Northwest gets much more rain than other areas in the country, rain is a big contributor to weathering of headstones. Granites, from what I learned in class and through the article, are more ideal than marble because they do not react to acidic rain and so are not as weathered in appearance as marble headstones. So, if someone were to choose between marble and granite, particularly for a headstone in the PNW, granite is a better choice to commemorate the person.  

What I learned and future questions:

One thing I had not thought about that the article brought to my attention is that, until recently, people were limited to local materials to create headstones. This is obvious in retrospect, until global trade was common and accessible it would have been impossible to use foreign stones for graves. Also, it is likely some materials that were farther underground would not have been known, never mind used for headstones. This leads to my question, when was the use of marble and granite popularized and what led to its accessibility to consumers?

Source:  

Morgan, N. (2016). Gravestone geology. Geology Today, 32(4), 154–159. https://doi.org/10.1111/gto.12146 

 

How does atmospheric pollution affect the Pioneer Cemetery, and are additional conservation methods required? 

 Contributed by: Braylon Belloni

Geological Question: Walking around the Pioneer Cemetery, I noticed a disparity in the weathering and erosion of the gravestones. In particular, I was surprised that many stones placed around similar times showed dramatically different weathering effects. Knowing that acid deposition and precipitation with unusual acidity can affect stones like marble, I began to wonder: How does atmospheric pollution affect the Pioneer Cemetery, and are conservation methods required? This question is related to geology as it considers the geologic effect of pollution.

Description of scientific article: In hopes of answering my question, I read an article by Inkpen (2013). I chose this article because Inkpen (2013) uses past rates of erosion on gravestones to postdict atmospheric pollution trends, which might give me some insight into how atmospheric pollution has affected Eugene in the past and indicate necessary restoration efforts in the Pioneer Cemetery. Erosion is the process of rocks naturally breaking down due to weathering. The article aims to calculate past sulphur dioxide (SO₂) conditions using Lipfert’s damage function, an equation derived from a data analysis of stones exposed to varying climatic/pollution conditions. Sulfur dioxide is an air pollutant. I think this will help me answer my question as Inkpen (2013) could aid me in understanding atmospheric pollution trends and discerning whether or not atmospheric pollution is still a potential contributor to the erosion and weathering of stones in the Pioneer Cemetery. 

Intersection between peer-reviewed research and observations on campus: In constructing the variation of Lipfert’s damage function that was used to postdate atmospheric SO₂ levels, Inkpen and references therein (2013) considered the contribution of acid rainfall and dry deposition to the deterioration of gravestones, calculating that these factors contribute at best 10% to erosion. While the exact causes of erosion were not observable to a significant extent in the pioneer cemetery, it was certainly evident that the area underwent a great degree of weathering. It could be seen that it is frequently affected by harsh weather (ie, heavy rainfall, wind), which would align with the thinking from Inkpen (2013), and support the idea that atmospheric pollution is not the only factor contributing to erosion. The Equation of the damage function was also altered to account for the solubility of calcareous stones because dissolution can occur more rapidly in these types of rocks (Inkpen, 2013). Calcareous stones are rocks like limestone and marble that are particularly sensitive to acidic substances. Observing differences in stones in the Pioneer Cemetery, it seems that this alteration to the damage function is necessary. Figure 2, a marble gravestone, shows significantly more weathering than Figure 1, which is granite. Because these two gravestones have both been in the cemetery for similar amounts of time, the difference in weathering would support the idea that marble is particularly susceptible to dissolution. To measure erosion on the marble gravestones, samples with lead lettering, once flush with the marble, were selected and the height difference between the eroded marble and the intact lettering illustrated the significance of weathering (Inkpen, 2013). The possibility of measuring erosion in this way seems very possible after visiting the Pioneer Cemetery. In figure 2, and on other marble gravestones, it appeared as though the outer layer of the marble was melted off, which made the edges of sculptures appear more rounded and details less defined. 

An answer to the question? My Initial question was: How does atmospheric pollution affect the Pioneer Cemetery, and are conservation methods required? While this article did not answer my question explicitly, it gave me some insights into how atmospheric pollution might be affecting the Pioneer Cemetery. The study found relatively low atmospheric SO2 levels post-1950, which are inferred to be the result of legislation lowering atmospheric pollution levels (Inkpen, 2013). While the study focuses on the UK, I think a similar rise in environmental awareness might make the findings of reduced levels of atmospheric pollution in recent years applicable to the US and possibly the Pioneer Cemetery. This would mean that, at present, atmospheric pollution is affecting the cemetery at relatively low levels. However, the impact of SO₂ levels of wet deposition (acidic rain) cannot necessarily be calculated at present (Inkpen, 2013). It was also discovered that a cemetery’s relationship to urban areas has a large effect on damage caused by atmospheric pollution, whereas rural areas experience fewer effects (Inkpen, 2013). Being less exposed to urban industrial activity than the eastern United States, it can be inferred that erosion resulting from atmospheric SO₂ is less notable in Eugene than in many other areas. Overall, conclusions from Inkpen (2013) suggest that the pioneer Cemetery is affected fairly insignificantly by atmospheric pollution currently. Although the article did not discuss conservation efforts that could be employed, because erosion was easily observable in the cemetery, restoration of gravesites would seem appropriate. However, drastic conservation efforts moving forward might not be necessary. 

Something additional I learned and future questions: From the article I read, I learned that calcareous stones, like limestone and marble, have a rate-limiting reaction to atmospheric SO₂, meaning that above a certain level, the stone is unable to react quick enough to erode (Inkpen and references therein, 2013). This made me think that there is a potential maximum effect of atmospheric SO₂ on gravestones, which was really interesting. However, brainwashing can remove weathering products from the gravestone, which can expose new surfaces to be eroded (Inkpen, 2013). This was very interesting to me as Eugene experienced a lot of rain, meaning that the pioneer cemetery could be particularly reactive to the effects of atmospheric pollution. From the scientific literature I read, I mostly gained insights into the way that acidic rain could affect the cemetery. Now, knowing that dry deposition of SO₂ can also cause erosion, I began to wonder how and where dry deposition is an issue. This article made me think: Does Dry deposition of atmospheric SO₂ disproportionately affect climatically dry areas of the world, or is industrial activity, regardless of climate, the primary cause in determining regionality of erosion causing pollution?

Sources Cited:

Inkpen, R. (2013). Reconstructing past atmospheric pollution levels using gravestone erosion rates. Area, 45(3), 321–329. http://www.jstor.org/stable/24029904