erosion and soils
mASS MOVEMENTMass movement or mass wasting refers to several processes that have the following in common:
CAUSES Down slope movement of rock or weathered material, Movement is due to pull of gravity, There is no flowing medium (water, air or ice) that carries the material. Generally, mass wasting occurs when gravitational forces exceed frictional or shear forces (strength) of material. HOW IT THIS IMPORTANT Processes represent a significant hazard to property and people, Need to identify where and under what conditions these processes occur, Avoid construction in areas prone to mass wasting or attempt to prevent mass wasting DRIVING FORCE BEHIND MASS WASTING Weight (amount) of material on slope, Resistance of the material, Steepness of slope, Saturation (water holds particles together, but too much water acts as a lubricant), Biological factors such as vegetation, Triggers (weakened planes) POSSIBLY TRIGGERED BY- 1. Earthquake 2. Construction work (blasting) 3. Flooding HOW MASS MOVEMENT IS CLASSIFIED Creep: slow and steady movement of small particles Flows (mudflows): materials move as though they are a thick liquid Slides: rapid movement of a block of rock, soil, and debris; also called debris avalanches Slumps: rapid slide of materials along a curved surface Avalanches: landslides that occur in mountainous areas with thick accumulations of snow Rock falls: Sporadic, rapid movement of large, loose materials DEPOSITS OF MASS MOVEMENT Mass wasting produces sediment deposits. These deposits commonly contain a wide range of sizes of particles (they are "unsorted"). The deposits do not show layering (they are "unstratified") HOW DO MASS MOVEMENTS EFFECT PEOPLE Humans contribute to mass movement through activities such as road and building construction and poor land maintenance (ie septic tanks) Humans and property are also in potential danger of mass movement events, especially in areas of steep slopes, supersaturated soils, and natural triggers like tectonic plate movement HOW DO WE PREVENT MASS MOVEMENT? This is NOT possible. A better question is “how do we lessen the effects” of mass wasting? •1. Remove weight from slope •2. Vegetation •3. Drainage systems to divert running water •4. Cables and anchoring systems (steel likes and fences) SOIL is a loose mixture of rock fragments, organic matter, water and air we as humans are directly and indirectly dependent on soils HOW DOES THIS FORM? begins with bedrock organisms live among them organisms fertilizer soil living things decompose forming Humus then larger animals loosen up the mix of particles SOIL HORIZON top layer contains more weathered material compared to the lower layers soil developed from the bedrock below it is residual A HORIZON-TOPSOIL B HORIZON-UNDER TOP SOIL AND LESS THAN HUMUS C HORIZON-THE LAYER OF SOIL IMMEDIATELY BELOW THE SOILO HORIZON-THE LAYER WITH THE MOST ORGANIC MATTER PERCENTAGE SOIL TEXTURE describes the mixture and make up of the soil can be defined as sand, silt, or clay the darker the color the better the organic matter SOIL FERTILITY describes how well a plant grows humus,minerals, and nutrients SOIL HORIZONS |
See Some Examples
how to find out soil types
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