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ESCI
finals
| Question | Answer |
|---|---|
| What is mass wasting? | Mass wasting refers to the downslope movement of rock, regolith, and soil under the direct influence of gravity. |
| Where does mass wasting occur? | In areas that are rugged, young mountains. As landscape ages, less dramatic downslope movements occur. |
| Trigger Factors | Saturation od the material with water. Oversteepening of slope. Removal of anchoring vegetation. Ground vibrations from earthquakes. |
| Effects water has on mass wasting | Reduces friction, destroys particle cohesion, and water adds weight. |
| Role of mass wasting | Transfers debris downslope where a stream carries it away to the ocean. |
| River valleys wider than deep | If streams were responsible for creating the valleys where they flor the valleys would be very narrow. Most river valleys are much wider than deep because mass wasting supplies materials to springs that run off from the river. |
| How can human activity sometimes lead to mass wasting events? | Deforestation, removal of vegetation (fire human/natural), undercutting slopes, and vibrations from human activities. |
| What factors are mass wasting processes classified? | Type of material involved. Type of motion. The velocity of movement. |
| Fall | Free-fall of pieces. |
| Slide | Material moves along a surface. |
| Flow | Material moves as a viscous fluid. |
| Slump | Slow and short movement of a mass of rock or unconsolidated material as a unit along a curved surface. Occurs along oversteepened slopes. |
| Rockslide | Blocks of bedrock slide down a slope Fast&destructive Where the rock strata are inclined/where joints&fractures exist parallel to the slope When the rock unit is undercut at the base of the slope It loses support and the rock eventually gives way. |
| Debris Flow | Mudflow–fine grained material Flow of solid®olith with a large amount of water. Often confided to channels. Serious hazard in dry areas with heavy rains. Debris flows composed mostly of volcanic materials on the flanks of volcanoes are called lahars. |
| Earth Flow | • Form on hillsides in humid regions • Water saturates the soil • Commonly involve materials rich in clay and silt |
| Lahar | Volcanic debris flow Loose pyroclastic material Rain/melting snow saturates soil&rock Very fast flowingup to 100 mph Moving lahar looks like a mass of wet concrete that carries rock debris size clay to boulders-10m in diameter Can occur anytime |
| Creep | • Gradual movement of soil and regolith downhill • Aided by the alternate expansion and contraction of the surface material |
| Solifluction | Common in regions underlain by permafrost. Creep that occurs in permafrost. Melting of soil water occurs from the surface down. |
| Permafrost | Permanently frozen ground found where summers are too cool to melt more than the shallow surface layer 80% of Alaska 50% of Canada and a substantial portion of Siberia Can produce unstable ground if a building is built on that area then it can sink |
| Vaiont Dam Disaster | Worst dam disaster in history. The filling of dam caused change in subsurface hydrogeology. Slope was moving downard and then slipped. About 7 min killed~2600. 240 million m3 of rock incolved in landslide fell into reservoir and produced a 328ft high wave |
| La Conchita | Mudslide swept through La Conchita on 1/10/05 Prolonged & intense rain. The town is situated on a narrow coastal strip that consisted of poorly sorted marine sentiments and weak cemented layers of shale and sandstone. It’s not likely to be the last. |
Created by:
kilong
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