Preliminary Report of Environmental Findings
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Preliminary Report of Environmental Findings
Southern New Hampshire University
PHY 103
2 March 2024
This report is an environmental analysis of the proposed project site and it will include an
overview of the geologic makeup, the soil profiles, the stream development, the tectonic and weather analysis for the proposed project site. The following report will reveal threats that make investing in the proposed project site a risk. Between volcanic eruptions, earthquakes mass waste, and flooding. All of the following pose substantial threats to the proposed development. First and foremost, the most immediate threat to the site itself is its close proximity to Mount Jefferson. Historically, Mount Jefferson is a stratovolcano that has erupted eight times with an reoccurring interval of one eruption every 613 years and well the last eruption was around 631 years ago and this puts the volcano at an overdue risk for another volcanic event. Next, this area is at risk for very strong earthquakes. They get one high magnitude earthquake around once every 85 years and the last high magnitude earthquake that hit the area was around 85 years ago which puts the proposed site at a risk for another event. Third, flooding and waste disposal events pose a very significant threat to the proposed location. On average we discovered
that the area gets a strong rainfall event once every 10 years which poses a threat due to the soil and the location of the proposed project site being prone to rapid erosion and when we talk about
these kinds of events, this leaves the other sites that are at a different risk due to the river nearby making the area in a flooding risk. If we are to continue with the proposed development, very special attention is to be paid to these hazards to mitigate possible future losses.
First of all the area does display a diverse area of rock types which indicates a complex geological history with a moderate erosion risk due to the soil depth and slope variation. Starting off, We have layer A which is limestone, limestone is a sedimentary rock that is primarily made up of calcite. It is typically made of biological sediments that were derived from more marine organisms, however in the rock, the percentage consists of sediments that likely precipitated
directly from seawater itself. With the presence of limestone in the area this points us to the conclusion that at some point in the history of the area, the surrounding area was likely marine. Moving onto the next layer, this layer is made up of sandstone, a sedimentary rock that is made up of a sand-sized grain of minerals, rocks or organic material. When we talk about sandstone, it is generally formed in sandy environments such as in deserts or beaches, this also leads us to believe that the area was marine at some point. The next layer seems to be made up of a second layer of limestone. With there being a layer of sandstone sandwiched between two layers of limestone, this could lead us to believe that there was a point where the environment dried up before reforming into marine again. The next layer is an organic sedimentary rock called coal. Now coal is produced in environments such as swamps where the plant matter is able to accumulate without completely decaying. The layer after is a siltstone, this is a detrital sedimentary rock that is made up of some clay-sized sediment that is intermixed with a larger silt-sized grain. The next layer is another layer of coal and the layer after is another layer of sandstone. The next layer is made up of a rock called schist, schist is a metamorphic rock that is typically derived from shale, mudstone, or siltstone. Now because the last layer of rock is layer H, it can be assumed that the siltstone went through metamorphism as it was buried and exposed to the heat from the layer after. The last layer, layer I is a layer of igneous rock called granite which is formed by granitic magma cooling and solidifying under the surface. When we date the formations from the youngest to the oldest. This shows the volcanoes vent to be the first and to not be impacted by the fault. Now, if the fault moved after the vent had formed, the shift seen would be present like in every other layer. Now how the vent was formed was by magma trying to find its way to the surface through the many layers of rocks. Next, we have the fault itself which id say would be the next youngest feature, I say this because we can
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see how it has an impact on every layer in the cross section minus the vent. Looking at the fault, it is known as a reverse dip-slip fault, and this results in compressional stress and one wall block going up while the footwall block stays. For the layers, Layer A would be the youngest layer because its at the top, simple, and layer I would the oldest. So going down A-I, you can see their age kind of in sequence. Now the soil diagram we can see that on the first one, diagram A, the O horizon itself is very thick. This could imply that the area was very thick forest which led to very minimal erosion and this allows the top layer to thicken and build. On the next diagram provided, this shows an extremely thin O layer and as well a thick A layer. This could tell us that the soil in the area could have less biological debris or that the area itself is very prone to erosion and that caused them to erode away before they could form. Now with the last diagram, Diagram C, this shows another extremely thin O layer but at the same time the missing presence of an A layer but
also the B layer is also smaller when we compare it to the other diagrams. When I did research on this, it seems like it is a key indication that the area itself has rapid erosion and an arid environment. If we use the topographic map, the areas like the valleys that have soil profiles kind
of like diagram A would be less prone due to the stronger presence of an O layer and A layer.
The biggest impact I think that geology could have on the area itself is its proximity to the fault line as well as the volcanic vent. The vent itself should be continuously monitored for signs of activity. But with the fault, if it ever slips, it could cause death and major damage to the area. With the area having limestone deposits the surrounding areas could be at risk for sinkholes. When looking at the topographic map that was provided, there are a lot of areas and features that I see that I feel like can be explained by stream processes as well as erosion. I feel
like the McKenzie River is the main cause of the erosion around the area. If you look at it, it carves a path through the terrain until it combines with the Willamette river near Eugene. The rivers in the area erode the land away and has created the steep valleys and the mountains in the area near the project sites. Now the rivers move more westward and around that the terrain becomes flatter and closer to a base level. This is an area where it widens out and the river just kind of meanders, creating what is called a floodplain.
How the floodplain was formed, was by the river itself downcutting close to a baseline, this allowed the river to kind of meander and slowly erode side to side. With the rivers historical data, the proposed development project sites A and B would be at an increased threat of floodwaters. Now, Over time the constant erosion of the river would deteriorate the soil and kind of just make it all unusable for development. The repeated flooding and the constant deposit of sediment and the erosion of the bedrock could create sinkholes and this should be emphasized when we talk about the development of this area. I feel like it is the biggest risk when we talk about this proposed development. Now even though project site C is at a higher elevation, I still feel like it is at a great risk of rapid erosion due to high precipitation. Now, I feel like with tectonic elements, we have the most obvious one near the proposed developments would be the fault which happens to go through all of the sites. Another major risk
I would say when it comes to the proposed developments would be Mount Jefferson, and Mount Jefferson is a stratovolcano that could be active still. These formations are a direct result of a subduction along the plate boundaries. Now as the Juan de Fuca plate meets the crust of the North American plate, an convergence boundary occurs. With convergence boundaries the denser
material of the oceanic plate is subducted under the lighter continental crust, results in the partial melting of lithospheric materials. When this rock melts, the materials become less and less dense
and can eventually find its way to the surface, this results in volcanic eruptions and volcanoes. The fault that runs through the development plan is because of plate tectonics. As the North American plate shifts, it interacts with neighboring plates, this pressure builds up in the crust. Afet enough pressure is built, there is a slippage that results in an earthquake. When we look at the historical data, the fault itself poses a pretty major threat the the development area. When looking at the history of the fault data, the last seven earthquakes that were recorded along the fault line are registered as a 6.0 or greater, and two of them were registered at a 7.0 and can be considered major earthquakes. I would say that depending on the size of the proposed development, if we got another earthquake of that size it could honestly result in the loss of life but as well as a hefty amount of money in damages to the infrastructure. On average the fault line produces an earthquake once every 85 years so the chances of there being another 6.0 or greater earthquake should be very much so considered with this development. I would say that the threat of a volcanic eruption from Mount Jefferson is something that should also be heavily considered. When we look at the data for Mount Jefferson, it has experienced 8 eruptions over the past 5000 years and one of them ranked at a 6 on the VEI (Volcanic Explosivity Index) scale. It has had 2 VEI 5 events that are present in its historical data. I would say that another eruption of this scale would most definitely impact one of the developments within the range of Mount Jefferson, including a threat from lahars. However the average interval between the eruptions is give or take 1000 years, it has been 631 years since the last eruption and that one was a VEI 4, so I’d for sure say that we should take the possibility of volcanic activity into consideration when planning to develop within the range of the volcano.
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Looking at the climograph, the mean temperature for the area is around 50F or 11.1C, while the mean precipitation is give or take 3 inches. In the summer months, specifically between July and august, they have the highest temperatures with the average being around 63 degrees. Now the temperature was higher but the precipitation wasn’t even an inch and that makes these months the driest. The months of December through February had by far the coldest temperatures, the temperatures were around 40F. The months between November and January had the most rainfall with the average being around 5 inches. With the area of our developments, id say we have to keep an eye out and plan for storms that can be associated with polar fronts due
to the boundary between cold winds from the polar north and warm winds from the equator.
Now, with the information presented in the climograph, thunderstorms and rain events are
very possibly as the cold fronts move through the area. Id say that the highest precipitation events should happen between the winter months and with this information, it would make the formation of blizzards and other winter based storms uncommon. With all of the historical data based on precipitation, we can see that the greatest precipitation event happened on Nov 2
nd
1917
and the event itself produced over 12 inches of rainfall.
The way you calculate the recurrence interval is by dividing the number of years on record by the number of events. The formula is R=N+1/m. If we use the numbers we were given,
we have 97 years of data and 10 events. So we would do R=(97) +1/(10). And that makes it around every 9.7 years we get a rain event. Heavy rain itself isn’t very common for the area itself, but when you look at the calculations that were just done, they do still happen nonetheless.
The sites lie near a floodplain which makes the area at risk of flooding. I would say that with the hazards that are associated with the area, I think that the project by far raises some concerns. Between the treat from tectonic activity and the volcanic activity
cannot be ignored nor put to the side. Id say that the projects being so close to Mount Jefferson when its considered to be overdue for a volcanic eruption is of great concern. The possibility of the death and devastation from the pyroclastic flows, lahars, earthquakes, and ashfall if an eruption were to happen would pose major threats to the sites. The average earthquake happening
85 years, the area is statistically overdue for another event. The problem with earthquakes is that it can cause damage to structures and life. The composition of the ground can cause the formation of sinkholes and the area is a floodplain and this brings up another risk of there being floods. I would go out of my way to say that the risks associated with this site are by far not worth. The possibility of the loss of life and the hazards have the possibility of offsetting any kind of gain that can be made in this area.
Encyclopædia Britannica, inc. (n.d.). Polar Front
. Encyclopædia Britannica. https://www.britannica.com/science/polar-front Floodplain
. Education. (n.d.). https://education.nationalgeographic.org/resource/flood-plain/ Limestone: Characteristics, uses and problem
. GSA. (2016, October 13). https://www.gsa.gov/real-estate/historic-preservation/historic-preservation-policy-tools/
preservation-tools-resources/technical-procedures/limestone-characteristics-uses-and-
problem#:~:text=Introduction,fragments%20and%20other%20fossilized%20debris. Sandstone
. GeoKansas. (n.d.). https://geokansas.ku.edu/sandstone#:~:text=Sandstone%2C%20a
%20sedimentary%20rock%2C%20is,and%20ground%20down%20into%20pebbles. Schist
. geology. (n.d.). https://geology.com/rocks/schist.shtml USGS volcanoes. (n.d.). https://volcanoes.usgs.gov/observatories/cvo/Historical/LewisClark/
Info/summary_mount_jefferson.shtml#:~:text=Mount%20Jefferson%20is%20one
%20of,culminated%20about%2015%2C000%20years%20ago. Recent earthquakes near Eugene, Oregon, United States
. Earthquakes in Eugene, Oregon, United States - Most Recent. (n.d.). https://earthquaketrack.com/us-or-eugene/recent
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