PHY 103 Final Project

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Southern New Hampshire University *

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PHY103

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Geology

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Jan 9, 2024

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docx

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Preliminary Report of Environmental Findings 1 Preliminary Report of Environmental Findings Chylah M-M. True Southern New Hampshire University (SNHU)

Preliminary Report of Environmental Findings I. Executive Summary: This report means to offer a fundamental report of the geological and environmental discoveries for the proposed Walterville, OR project site. This report will briefly discuss any tectonic risks, such as presence of fault lines, potential plate movement, and resulting seismic or volcanic activity in the area, as well as climate concerns, including an analysis of hazardous storms, precipitation, and temperature considerations for the development site near Camp Creek Cemetery. The geological analysis will also include an analysis of the soil profiles for the proposed sites. The site’s proximity to Mount Jefferson poses the most obvious threat. This stratovolcano has erupted 8 times in its history, with 1 eruption occurring every 613 years. The volcano has been dormant for 631 years, making it past due for another eruption. Additionally, this region is susceptible to large-scale earthquakes. This location is at risk for another large earthquake, with the most recent high-magnitude quake occurring over 85 years ago and occurring on average every 85 years. A significant risk exists from massive waste events and flooding. With a recurrence interval of 9.8 years, high magnitude rainfall has been observed. Area C’s soil and location make it vulnerable to rapid erosion during these kinds of events, and the location of areas A and B put them at risk of flooding from the river nearby. In order to reduce potential losses in the future, these risks require special attention if development is to proceed. II. Basic Geology: Limestone (layers A & C) is a biochemical sedimentary rock formed by the breakdown of coral, algae, and shells as well as animal waste. Calcite, a type of calcium carbonate is what makes up most of this. The limestone demonstrates that when layers A and C were shaping, there

was a waterway or freshwater lake at the site, or it was essential for the ocean bottom. Sandstone (layers B & G) is a detrital sedimentary rock that forms when quartz or calcite, organic material, or other minerals were compressed together with sand-sized particles left over from the weathering of rocks. Sandstone indicated that deposition from lakes, rivers or the ocean floor is present. Coal (layers D & F) is a fossil fuel and organic sedimentary rock that forms when plants are kept from decaying in low-oxygen environments like swamps and then buried in the sediment and compressed and compacted over time in warm conditions. The presence of coal indicates that the climate at the time these layers were formed was swampy. Siltstone (layer E) is a detrital sedimentary rock that structures in a similar style as sandstone, except rather than sand- sized particles, it is made through the compaction of residue measured particles and is usually ruddy or grayish in variety. Siltstone demonstrates that there was once a delta or glacier around the area. Schist (layer H) is a foliated metamorphic rock that forms when long, flat minerals are put under extreme pressure, heat, and chemical activity (Lutgens, et al. 2021). A slate step and a phyllite step must be used to transform schist. After the schist forms, it may change into gneiss if it is subjected to additional extreme pressure. The schist in the area demonstrates it is on the continental side of a convergent plate boundary. Granite (layer I) is an intrusive igneous rock that forms when molten material cools and hardens inside the Earth’s crust for a millennial or more (Lutgens, et al., 2021). The formation of large, visible mineral crystals found in granite is made possible by the passage of such an extended amount of time. It is for the most part made of quartz and feldspar which are reinforced through heat with different materials. Granite is a sign of an underground magma chamber and a subduction zone, where continental rocks are melting. Andesite (volcano & vent) is an extrusive igneous rock that typically occurs in thick lava flows produced by stratovolcanoes. Andesite indicates that a stratovolcano has erupted in the region,

resulting in andesitic lava flows and a subduction along the Juan de Fuca and North American plates in the development site that gave rise to the Cascade Range. With the utilization of relative dating, we can decide the time period for when each layer was shaped corresponding to different layers in the stratigraphy. In figure 1, we can see that the layers framed from the oldest to the youngest are H (Schist), G (Sandstone), F (Coal), E (Siltstone), D (Coal), C (Limestone), B (Sandstone), I (Granite), A (Limestone), and then volcano and vent (the Andesite bedrock) being the youngest as the fault does not affect the vent. We know that the granite dike, layer I, is younger than all but layer A because it cuts through the other layers, indicating that they had already formed, whereas layer A was formed later and is the youngest because it was not cut by it. We can see that the fault that runs through the cross-section formed last because it cut through all of the layers after A formed. Layer A formed the fault, which is a reverse strike-slip fault. As the fault moved the rock layers up on the right, layer A eventually eroded, leaving no trace on that side of the fault and a smaller, more eroded layer B serving as the top layer. With the exception of the granite layer, all have horizontally flat horizons. The stone layer expelled vertical from the center, while different layers above it were framed by different measures of strain over significant stretches. Layers G and H could have formed simultaneously because the weight of the long, flat minerals caused by the pressure of the sandstone allowed the schist to form. Swamp-like circumstances probably won nearby for an extensive stretch after the sandstone frame, which is confirmed by the rehashing layers of coal in the cross-segment which structures from plant matter lowered in low oxygen conditions and is then compacted with tension by weighty silt layers. We can see that a thick layer of siltstone formed on top of the first layer of coal. This indicates that the sediment on top was very fine-grained and probably contain

clay or mud. One more layer of coal shaped, this time with sediments that would have been comprised of natural matter like green growth, coral, and shells as the following layer to frame was limestone. The arrangement of limestone as the following layer shows that the oxygen levels probably rose to have upheld the endurance of such natural matter from submerged organic entities. The subsequent formation of a layer of sandstone, probably as a result of deposition in the body of water, and a subsequent layer of limestone at the top point to the continued existence of organic underwater organisms at the time. A granite dike cut through the rock layers at some point prior to the formation of this final limestone layer. A fault event took place sometime after layer A was formed. After the issue framed, there was a huge disintegration that happened on the part of the shortcoming which was raised on the right-side causing layer A to be totally eroded and a piece of layer B to dissolve as well, representing the more modest layer B on the right of the fault. The fault and the volcanic vent are the geological features that may have the greatest potential of having a devastating effect on the subdivision or overlying neighborhood. If the fault slips again, the earthquake that follows could kill or damage infrastructures. It is important to keep an eye out for activity at the nearby volcanic vent. Sinkholes “are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them” as a result of the presence of the layers of limestone in the region (Water Science School, 2018). In soil profile 1, there is a slightly thicker layer of mineral topsoil and there is a layer of organic soil (O). Below layer A is a thicker layer of an accumulative mineral zone (B), followed by a larger layer of parent material (C) before the thin layer of the bedrock located at the bottom. Soil profile 2 has a much thinner layer of natural material (O) at the top alongside a skinnier

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