GEOG 2300 1st Edition Lecture 29Outline of Last Lecture I. AquifersII. Saving WaterIII. Water ProblemsIV. Withdrawing GroundwaterV. DeforestationOutline of Current Lecture I. Water UseII. Fluvial ProcessesIII. WeatheringIV.SlopesCurrent LectureI. Water Use A. Most water use is used for toilet flushing and bathingB. Very dry conditions in southern California, but wet conditions along western side of Sierra NevadaC. They have put a lot of money into water diversion projectsD. Preventing erosion can help against the loss of valuable soil and the addition of sediments to streamsE. To prevent erosion you can walk on sidewalks and established trails, park on pavement or gravel and not grass, and try not to stand on steep edges of stream banks II. Fluvial ProcessesA. Fluvial Processes: water flowing across the surface, includes overland flow and stream flow, dominant features of landscape generally created by waterB. Denudation: wearing down of rocks, processes of erosion, transport, deposition, creates erosional landforms and depositional landformsC. Landforms make up landscapesD. Erosion: changes surface, transport: moves material by air and water, deposition: deposits sedimentsE. Weathering: rocks are broken down  mass movement: gravity moves debris erosion: weathered debris is removedIII. WeatheringThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.A. Mechanical: imposed stresses break rocks apart; chemical: alters chemical composition of the rock, making it weaker; biological: includes digging of animals, rooting in plantsB. Physical weathering: mechanical, no chemical changes, frost action: water freezes in spaces and expands, thermal expansion, unloading (Yosemite domes), salt wedging (arid regions), rocks can separate by joints or grain by grain (granular disintegration)C. Chemical weathering: minerals are chemically altered, some are resistant (quartz), others are not (limestone once chemically weathered, can dissolve), 3 types: hydrolysis, oxidation, carbonationD. Hydrolysis: if water added, some minerals expand; altered version is softer and weaker; feldspars weathered to clays; spheroidal weathering may result from hydrolysis, outer layers of rock flake ofE. Oxidation: minerals react with oxygen, iron and aluminum oxidizes to produce a reddish color in soilF. Acid action: water can be acidic (carbonic acid), carbonic acid reacts with the carbonate minerals in rocks like limestone  caves and karst landformsG. Which of these is not a form of physical weathering? CorrosionH. Biological weathering: influence of plants and animalsIV. SlopesA. Slopes: rocks are weathered below the soil as well as when exposed to the surface, resulting materials move down hill by mass wasting; colluvium: moved by gravity, alluvium: moved by riversB. Slopes are made up of or at least covered by loose debris, material moves downslope because of gravity, they’re subjected to a force greater than the friction holding them together, something reduces the friction (water) C. Angle of repose: maximum angle that loose material forming a slope can maintain without slipping, it’s a balance between gravity and friction, solid rock could be 90 degrees, moisture usually increases the angle of repose, loose material and soil are about 13-45 degrees D. Slope erosion: overland flow picks up small particles, size depends on speed and volume of water flow and mechanisms that hold slopes together (such asvegetation), normally the soil removed should balance new soil added in the weathering of rocks (soil does not generally grow deeper or shallower over long time periods)E. Accelerated erosion: human activities can increase rate of soil erosion, agriculture, development, splash erosion: falling water droplets moves soilF. Sheet erosion: overland flow removes layers of soil, can remove valuable topsoilG. Rill erosion: on steep slopes, rills are channels on the slope that widen and deepen (and become gullies)H. Colluviums: when soil particles reach the base of the slope, they accumulate in a layer of debrisI. Alluvium: any stream laid depositJ. Which describes the angle of repose best? The max angle that loose material forming a slope can maintain without