GEO101 (MOD3 Peer discussion response)
Im trying to learn for my Geology class and Im stuck. Can you help?
Please respond to both POST1 and POST2 in at least 200 words.
Required
- Chapter 5 Weathering, Erosion, and Sedimentary Rocks (Sections 5.1 & 5.2 only) in An introduction to geology. Salt Lake Community College. Open Educational Resource
- Chapter 10 Mass Wasting in An introduction to geology. Salt Lake Community College. Open Educational Resource
- Chapter 13 Deserts in An introduction to geology. Salt Lake Community College. Open Educational Resource
- Chapter 14 Glaciers in An introduction to geology. Salt Lake Community College. Open Educational Resource
Recommended
- Iverson, R. M., George, D. L., Allstadt, K., Reid, M. E., Collins, B. D., Vallance, J. W., …, & Baum, R. L. (2015). Landslide mobility and hazards: Implications of the 2014 Oso disaster. Earth and Planetary Science Letters, 412, 197-208.
- National Park Service. (2019, September 11). Mass wasting. Retrieved from https://www.nps.gov/subjects/erosion/mass-wasting.htm
- Omosanya, K. O., Harishidayat, D., Marheni L., Johansen, S. E., Felix, M., & Abrahamson, P. (2017). Recurrent mass-wasting in the Sorvestsnaget Basin Southwestern Barents Sea: A test of multiple hypotheses. Marine Geology, 376(2016), 175-193. doi:gor/10.1016/j.margeo.2016.03.003
Using your text and the library or internet resources, research one of the many varieties of mass wasting. Explain how it works, what type of material is involved, and that type of movement. In which regions might we find this type of mass wasting? Provide a real-life example of an event of this type. Once again, make sure that you come up with an example that hasn’t been discussed already.
POST1:
Mass wasting is when there is a downhill movement due to gravity that consists of soil or rock material and refers to all fast-moving material. Debris flow is a common type of mass wasting that consists of rapid movement. Flows are rapidly moving mass-wasting events in which the loose material is typically mixed with abundant water, creating long run-outs at the slope base (Johnson, Affolter, Inkenbrandt, & Mosher, 2017). There are two types of flows: debris flow which is made up of coarse material, and earth flow which is made up of finer material.
Debris flow commonly occurs from heavy rains with falls before flowing downhill and creating sections with a surface broken by ridges and channels. Hilly areas that are subject to long, heavy rainfalls are more susceptible to experiencing debris flow. In the United States, examples of these areas include Hawaii, northern California, Idaho, Washington, and Oregon on the West, and the Appalachian Mountains on the Central and East.
An example of debris flow in the United States actually occurred twice in the same location! In 1995, La Conchita, California experienced moving earth flow that damaged nine homes. A short week later, debris flow occurred in the same exact location damaging five more homes. The top of this slide actually had early warning signs with its tension cracks that eventually grew larger with the heavy rainfall during the winter of 1994/1995. This was likely the trigger that caused the earth flow and debris flow events in 1995. Again in 2005, ten years later, a rapid-debris flow occurred after the end of a 15-day rainfall. Vegetation remained relatively intact as it was rafted on the surface of the rapid flow, indicating that much of the landslide mass simply was being carried on a presumably much more saturated and fluidized layer beneath (Johnson, Affolter, Inkenbrandt, & Mosher, 2017). This event damaged 36 homes and killed 10 people.
References:
Johnson, C., Affolter, M., Inkenbrandt, P., & Mosher, C. (2017). An introduction to geology. Salt Lake Community College. Open Educational Resource. Retrieved from http://opengeology.org/textbook/
POST2:
Debris flow is a type of mass wasting. A debris flow is a moving mass of loose mud, sand, soil, rock, water, and air that travels down a slope under the influence of gravity. To be considered a debris flow, the moving material must be loose and capable of flowing down the slope. Usually, the flow is not fast and it creeps down the slopes. However, the fast ones are the ones that attract attention and become very dangerous. The speed and volume of debris flows make them very dangerous. Every year, worldwide, many people are killed by debris flows. This hazard can be reduced by identifying areas that can potentially produce debris flows, educating people who live in those areas and govern them, limiting development in debris flow hazard areas, and developing a debris flow mitigation plan.
Highly destructive debris flows occur in many areas across the United States. Hilly areas subject to prolonged, intense rainfall are particularly susceptible. Areas throughout southern California and San Francisco Bay Area, where I live, are frequently beset by debris flow problems, and public agencies have expended vast resources on massive debris-protection systems. Montecito, a city in California, has been a victim of one of the deadliest debris flow. In January of 2018, Montecito experienced heavy rainfall in a short period of time, causing water, mud, trees, rocks, and boulders from the Santa Ynez Mountains to flow down creeks and streams into the Montecito area.
