4. Physical weathering: joints in rocks • 1 Duration of weathering • 2. Bedrock type • 3. Climate • 4. Topography 5. Soil: the residue of weathering • The basic soil-forming processes result in losses (transformations) and additions (translocations). 6. Mass wasting • Mass wasting includes all processes by which masses of rock and soil move downslope. • Mass movement occurs when the force of gravity exceeds the strength of the material and it moves downslope. Three primary factors o Nature of slope materials (angle of repose)
Weathering, Erosion, and Mass Wasting 07:20 Unconsolidated materials Sand and silt Tock fragments, sand, silt, and clay Consolidated materials Rock Compacted (cohesive) sediments and soils o Amount of water Water content Lubrication Liquefaction o Steepness and stability Angle of slope Accumulation of rubble Breakage into large blocks • Triggers of mass movements o Earthquake vibrations o Rainfall and water infiltration o Overloading 7. Classification of mass movements • Three characteristics used o Nature of material (rock or unconsolidated)
Weathering, Erosion, and Mass Wasting 07:20 o Velocity (slow, moderate, or fast) o Nature of movement (flow, slide, or fall) • Rock mass movements o Rock falls o Rock slides o Rock avalanches • Unconsolidated mass movements o Creep o Earthflow o Debris flow o Mudflow o Debris avalanche o Slump o Debris Slide • Understanding the origins of mass movements o Examples of landslide disasters Spanish Fork, Utah (1983) Gros Vertre Valley, Wyoming (1925) Vaiont Dam, Italy (1963)
Hydrologic Cycle and Groundwater 07:20 Basic considerations • Hydrology is the study of movements and characteristics of groundwater. • The hydrologic cycle has a profound effect upon climate prediction • Water is vital so we must understand where to find water and how water supplies cycle through the Earth 1. Water and reservoirs • Water o The essence of life—necessary for the survival of all organisms o Used for many things, but commonly taken for granted o It is a critical resource o Unique substance—exists as gas liquid and solid on Earth’s surface o It participates in all geological processes • Salt Water 95.96%/Fresh Water 4.04% • Distribution of Fresh Water o Most fresh water is in glaciers (74%) o Most unfrozen water is groundwater (26%) o Not all groundwater is fresh o There is a limit to the amount of fresh water which we can use. • Reserves are limited : o They are rapidly decreasing in quality and quantity o They are nonrenewable o Will there be sufficient quantities to sustain out future needs?
Hydrologic Cycle and Groundwater 07:20 o Is the quality adequate for the uses intended? o Is it being used efficiently with a minimum and waste? • Hydrologic Cycle : o Description of pathways water moves through various reservoirs o Evaporates from land and sea surfaces and returns as precipitation as
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