Post by: Diego Escobedo, Jillian McAlpin, Mikayla Gee

GPS coordinates of campus feature (in decimal degrees): (44.04629, -123.07371)

Location on Google Earth: Site 1

Location and general description: 

Our initial reaction to Cascade Charley, the waterfall next to cascade, was about the odd placement of rocks in the waterfall. We initially thought it had something to do with the fact the waterfall is placed in the courtyard of the Geology department at the University of Oregon, but after doing some research on the waterfall itself we learned more. Cascade Charley is a waterfall and art piece in the middle of the Cascade courtyard located outside of Cascade Hall. It is an art installation created in 1991 by artist Alice Wingwall. She created this piece while going blind and thought to make the art accessible to all people, not just people with vision. On the ground in between Cascade and Deschutes hall there is another art installation called the science walk with pieces of inlaid stone. In front of the waterfall if you stand on each inlaid stone you can hear a new and different sound the waterfall makes. The artist originally created this to be a place of great contemplation where everyone is able to experience the wonders of the waterfall. 

Geological Observations:

In this waterfall, multiple types of rocks were placed along the feature. Some rocks travel down the waterfall feature, and some are located in the pool at the bottom of the waterfall which can be seen in Figure 1. This waterfall consists of both mafic and felsic rocks, including 16 granite rocks, which are felsic, and 11 basalt rocks, which are mafic. Mafic and felsic are terms to describe the composition of a rock, where mafic rocks contain much less silica (a mineral) than felsic rocks do, and therefore are darker in color as seen in the dark color of the basalt in Figure 2. The granite seen in Figure 2 is reddish in color, with black and white spots, demonstrating that the rock contains minerals of hornblende and quartz. The red color of the granite is most likely attributed to the mineral, potassium feldspar (Mossfords, n.d.). Our group also counted 5 sedimentary rocks that are dispersed throughout this feature. Some rocks are modified and others are more spherical shaped as this piece is a combination of human construction and natural rocks. The majority of the waterfall, including the base structure of the waterfall is composed of cement as well as tile. The cement is not uniform and the rock components are moderately sorted as seen in Figure 2 on the lower half of the image. 

Group Citations:

Mossfords. (n.d.). How Does Granite Get Its Colour? Mossfords. Retrieved June 5, 2025, from https://mossfords.com/education/how-does-granite-get-its-colour/

How much of an impact does the flowing of water in Cascade Charley have on the erosion of the waterfall’s rocks? 

Contributed by: Mikayla Gee

Geological Question: 

My question for this field post is: How much of an impact does the flowing water in Cascade Charley have on the erosion of the waterfall’s rocks? Throughout our Geology of Campus course, we have looked at water energy and erosion in relation to different types of rocks. I wanted to understand how a man-made structure could replicate some of these attributes in nature. Also, when viewing outdoor art, fountains, or waterfalls, I never truly thought about how these structures would erode or break down, even though they are made from our natural resources: rocks and water. Learning the consequences of water flow on the waterfall feature can also help plan prevention methods to keep these structures intact.

Description of scientific article: 

I chose the article by Alves et al. (2021), as it discusses how water affects stones in man-made structures. The article addresses how freezing temperatures, water immersion, water flow, and water-caused pollution can all affect the rocks in structures such as fountains (Alves et al., 2021). I believe this article will help me answer my geological question of whether flowing water affects the erosion of the rocks in our waterfall feature, as the article directly relates water and its interactions with rocks (Alves et al., 2021). Also, this article is specific to man-made features, such as fountains, and the Cascade Charley waterfall is also man-made (Alves et al., 2021). Therefore, the findings in this article may accurately describe the erosion in our waterfall as the environment of rock erosion in the study is similar to our feature.

Intersection between peer-reviewed research and observations on campus:

In the article, Alves et al. (2021) state that the flow of water impacts rock erosion. The article addresses certain studies that observed water flow affecting carbonate rocks (Alves et al., 2021 and references therein). Carbonate rocks are sedimentary rocks made of carbonate minerals, and an example of a carbonate rock is limestone (Geology is the Way, n.d.). From what I have observed, the Cascade Charley waterfall contains no limestone or carbonate rocks. Nevertheless, the type of rock observed in the article can help me to hypothesize how water movement interacts with the rocks in the waterfall. Our team identified two types of rocks in the feature: granite and basalt. Granite can consist of feldspar and quartz, and their rating on the Mohs hardness scale is 6 and 7, respectively (Earle, 2019) (Volcano World & Oregon State University, n.d.). The Mohs Hardness scale is a scale to determine the durability of a type of rock, and the number provided correlates to how easy it is to scratch the material (Walborn, 2023). Basalt consists of the mineral augite, which has a Mohs hardness scale of around 6 (Volcano World & Oregon State University, n.d.). Limestone is mostly made of calcite, with a Mohs hardness of 2 (Volcano World & Oregon State University, n.d.). Given that granite and basalt both have a higher hardness level and, therefore, greater durability, these two types of rocks may not erode as easily as the carbonate rocks the article describes (Alves et al., 2021). The durability of the granite can be seen in Figure 2, where the granite pieces do not look damaged and continue to hold the shape they were manufactured as, even though these rocks were placed in the waterfall 34 years ago. The basalt durability is harder to tell as I am not sure what the original shape of the rock was. Another aspect of the article that connects to our feature is rock erosion due to water exposure. The article relays how “wetting” stone and letting it dry causes erosion. Specifically, basalt is the least affected by downwearing compared to other rocks such as argillite and sandstone (Alves et al., 2021 and references therein). Downwearing is the erosion of the surface of a rock due to environmental stressors (Moura et al., 2011). Two basalt rocks can be seen in Figure 2, which are both partially submerged in the water and partially dry. The waterfall continuously wets the basalt, creating conditions similar to the actions described in the article. Since the article describes basalt as resistant to downwearing compared to other rocks, the water flow may not impact this type of rock in the feature to a noticeable extent. Again, observing if erosion has occurred in the basalt is difficult since I do not know what the original shape of the basalt rocks were. 

An answer to the question? 

The scientific article by Alves et al. (2021) only partially answered my question about the impact of water flow on the erosion of rocks in the feature. The article stated that erosion can occur from fountain water flow and provided evidence from a few studies in which limestone and carbonate rocks can degrade from this water movement (Alves et al., 2021 and references therein). However, limestone was not found in the waterfall feature. Therefore, it was hard to correlate the findings in the article and the feature. The article provided helpful information to infer the erosion of basalt and granite, which were the most abundant types in the waterfall feature, as well as the durability of these stones. The article did not provide quantitative evidence for the erosion of rock via water flow, which did not answer the part of my question of “how much” water flow affects the degradation of rocks. I believe information on the water flow rate would be beneficial to answering my question for future research. 

Something additional I learned and future questions:

While reading the article by Alves et al. (2021), I learned that the size and variation of holes (pores) in a rock dictate whether that rock will endure cracks and erode when exposed to freezing water. I also learned that the orange runoff on stone is caused by the interaction of water and the minerals in the rock (Alves et al., 2021). This runoff is due to sulfur oxidation, meaning sulfides in certain rocks, such as marble or granite, react with the water and cause the sulfide to be deposited elsewhere from its original position in the rock (Alves et al., 2021). Depositing means minerals are “dropped” in a certain spot. Whenever I saw the orange stain on rock features, I always thought there might be a piece of metal or pipe that was causing the rust-colored area. Instead, it is the stone that causes these stains. With the article, I was also able to infer the high durability of basalt and granite, which can possibly explain why the artist chose these rocks for the waterfall feature. Reading this article made me curious about the intersections between natural rocks and man-made environments. A question I have is: What are the erosion rates of industrial cement, and will manufacturing cement to replicate basalt or granite help the cement’s durability?

Citations:

Alves, C., Figueiredo, C. A. M., Sanjurjo-Sánchez, J., & Hernández, A. C. (2021). Effects of Water on Natural Stone in the Built Environment—A Review. Geosciences (Basel), 11(11), 459-. https://doi.org/10.3390/geosciences11110459

Earle, S. (2019). Physical Geology – 2nd Edition. Victoria, B.C.: BCcampus. Retrieved from https://opentextbc.ca/physicalgeology2ed/.

Geology is the Way. (n.d.). Carbonate Rocks – Geology is the Way. Geology is the Way. Retrieved June 5, 2025, from https://geologyistheway.com/sedimentary/carbonate-rocks/

Moura, D., Gabriel, S., Ramos-Pereira, A., Neves, M., Trindade, J., Viegas, J., Veiga-Pires, C., Ferreira, Ó., Matias, A., Jacob, J., Boski, T., & Santana, P. (2011). Downwearing rates on shore platforms of different calcareous lithotypes. Marine Geology, 286(1-4), 112-116. https://doi.org/10.1016/j.margeo.2011.06.002

Volcano World & Oregon State University. (n.d.). Mineral Show 1. Volcano World. https://volcano.oregonstate.edu/image-album/mineral-show-1

Walborn, H. (2023, April 12). Mohs Hardness Scale (U.S. National Park Service. Retrieved June 5, 2025, from https://www.nps.gov/articles/mohs-hardness-scale.htm

How does the erosion force of water impact iron rich rocks? 

Contributed by: Jillian McAlpin 

Geological Question:

When we first chose the waterfall as our geological site I was really interested in the flow of the water and how the force of the water could impact the rocks in the waterfall over a long period of time. I knew that obviously the water would cause the rocks to erode in some way but I wasn’t quite sure how the erosion would impact the different types of rocks differently. While looking through the waterfall and the different rocks I decided to pick my favorite to write this post about. I finally decided on a reddish tinted rock that you can see in the upper right corner of figure 2. Because the rock is tinted reddish I decided that it most likely contained iron, this fact was really interesting to me. I had no idea how an iron rich rock would erode, especially in a high impact area like a waterfall. This led me to question How does the erosion force of water impact iron rich rocks? 

Description of scientific article:

I chose the article Erel et al. (1992) because the research focuses on the relationship between iron and lead released because of erosion and how they impact water samples. This is important in answering my geological question and identifying what could happen to the iron rich rocks in the fountain.The article details how the deviation of iron and lead ratios in all the samples studied suggests different release and transport mechanisms in different rocks. Essentially different rocks will interact with iron and lead in water differently. This is really important in answering my question because it details how the iron in the water from one rock could potentially impact all the other rocks in the fountain. 

Intersection between peer-reviewed research and observations on campus:

In the article, Erel et al. (1992) states that according to their model the different ratios of iron and lead indicate different source compositions. Essentially the composition of the rocks in which the iron and lead came from are different and therefore their release mechanisms will also differ. When looking at different types of rocks biotite leachate yields a similar ratio as biotite which suggests a congruent release. A congruent release means that the entire mineral dissolves leaving no solid trace on the rock (Bricker 1994). This was not the case in the rock that I chose. There was a pretty visible residue left on the surface of the rock, while this may also indicate the rock not being fully eroded. The amount of time that this rock has been in the fountain suggests an incongruent release. 

An answer to the question:

The article by Erel et al. (1992) did not fully answer my question about the erosion force impacting iron rich rocks. The article studied erosion in only a certain sample size of rocks and did not include samples from man made waterbodies such as a fountain. While the article contained a lot of new and helpful information about the release and absorption of iron into rocks it failed to include information about my specific case. Because the fountain is an art installation there is no drainage point the water essentially cycles through this can lead to higher amounts of minerals such as iron in the water which could be the cause of such iron rich rocks. The article provided a lot of helpful information to continue my research, but failed to include information about my specific case. I believe that the information in this article is a great jumping point for information about iron rich rocks in bodies of water, but does not quite provide enough specific work to fully answer my question.

Something additional I learned and future questions:

I learned a lot of things in the article, but I also had a pretty difficult time reading it. My article was filled with a lot of scientific jargon and I oftentimes found myself looking terms up and trying to dissect everything, almost as if I was reading in another language. But I learned a lot about the erosion of rocks in rivers, especially rocks rich in iron and lead. One of the things that I really had no idea about before reading and researching was the fact that in the early stages of erosion and weathering lead sticks and gets trapped on iron rich surfaces (like rocks) and because both elements often come from the same styles of rocks and minerals then they get released into the water at similar rates, meaning that waterbodies that are often high in iron will also most likely be high in lead as well. I am curious to learn more about these implications for sources that reuse water, like my fountain, does that actually impact the iron and lead contents? Will rocks in this fountain be much higher in iron than naturally occurring streams and bodies of water? 

Citations: 

Erel, Y., & Morgan, J. J. ​ (1992). ​ The relationships between rock-derived lead and iron in natural waters. ​ Geochimica et Cosmochimica Acta, 56(12), 4157–4167. ​ https://doi.org/10.1016/0016-7037(92)90259-2

Bricker, O. P., Paces, T., Johnson, C. E., & Sverdrup, H. (1994). Weathering and erosion aspects of small catchment research. ​ In B. Moldan & J. Cerny (Eds.), Biogeochemistry of Small Catchments: A Tool for Environmental Research (pp. 86–105). ​ John Wiley & Sons Ltd.

How do compositions change within volcanoes? 

Contributed by: Diego Escobedo

Geological Question: Growing up in Oregon, I’m surrounded by basalt everywhere. The waterfall had some hand placed basalts in it and it got me thinking, How do compositions change within volcanoes? 

Description of scientific article: To help me start answering this question, I read about the Longgang volcanic field (LVF) and the Changbaishan volcanic field (CVF) in China and its geochemical characteristics (Zhao et al., 2021). I chose to read this article because Zhao et al. (2021) focus on the chemistry within the volcanoes, meaning they discuss the findings in a large sample size of volcanoes and present them in the journal article. 

Intersection between peer-reviewed research and observations on campus:

Zhao et al. (2021) talks about this concept of magmatic evolution. For example, the volcanoes in the CVF saw changes from primarily basaltic magma to acidic rhyolitic magma (Zhao et al., 2021). Zhao et al. (2021) suspect it’s likely from the pacific plate subducting around Northeastern Asia to create the more rhyolitic compositions. Rhyolite is an extrusive granite that is usually composed of quartz and feldspar. Zhao et al. (2021) mention that the LVF rarely underwent any magmatic evolution, which means it would be considered a monogenetic field and the CVF would be considered a polygenetic volcanic field. Since the basalt in the waterfall was fine grained and darker, I’d assume it came from a monogenetic volcanic field. 

An Answer to my question: While Zhao et al. (2021) did address the difference in the two volcanic fields, they were using a relatively small sample size in one part of the world. However, using inferences, I was able to gather that the change in compositions was likely due to shifting of tectonic plates. With this, I can apply that knowledge to other places sitting on rift zones to make my own conclusions. Even though I certainly learned from Zhao et al. (2021) about how these volcanoes underwent change, I wouldn’t say they entirely answered my question. 

Something additional I learned and future questions: Something interesting I learned from this article is that the upper mantle of the LVF may have undergone multiple periods of mantle metasomatism (Zhao et al., 2021). Mantle metasomatism is when preexisting rocks undergo compositional changes from interacting with liquids which cause chemical reactions and transform the rocks. In the article Zhao et al. (2021) discuss temperature and pressure as one of the things they recorded in their observations meaning they already have the resources to compare these numbers. With this in mind, I ask Under what conditions does mantle metasomatism tend to occur?

Sources Cited: 

Zhao, B., Xu, D., Bai, Z., & Chen, Z. (2021). Volcanism in the Longgang volcanic field of NE China: Insights from eruption history, volcano types and geochemical characteristics. In J. Xu, C. Oppenheimer, J. Hammond, & H. Wei (Eds.), Active volcanoes of China (pp. 27–39). Geological Society of London. https://doi.org/10.1144/SP510