Dig It Webquest | |
File Size: | 32 kb |
File Type: | doc |
Mass Movement |
The Dirt On Soil |
Mass movement/ mass wasting refers to several processes that have the folloing in common:
Downslope movement of rock or weathered material Movement is due to the pull of gravity There is no flowing medium (water, air, or ice) that caries the material Generally, mass wasting occurs when gravitational forces exceed frictional or shear forces ( strength) of material It’s important because Its 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 of attempt to prevent mass waiting Diving forces 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) POSSIBLE TRIGGERED BY Earthquake Construction work (blasting) Flooding Mass movements events are classified by Type of material that moves Nature of movement (slide, flow, or fall) How fast materials moves Creep- slow and steady movement of small particles Flows (mudflows) - materials move as though they’re 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 accumulation of snow Rock Falls- sporadic, rapid movement of large, loose materials 1.) Creep 2.) Slump 3.) Flow 4.) Slide 5.) Avalanche 6.) Fall People affect mass movement through activities such as road and building construction and poor land maintenance. Humans and property are also in potential danger of mass movement events, especially in steep slope areas, supersaturated soils, and natural triggers like tectonic plate movement. We can’t prevent mass movement it’s not possible. We can lessen the effects of mass wasting by Removing weight from slope Vegetation Draining systems to divert running water Cables and anchoring systems (steel like fences) |
soil- loose mixture of rock fragments, organic matter, water, and air that can support the growth of vegetation
humans are directly and indirectly dependent on the soil for plants and their products soil is a product of a chemical and mechanical weathering, the breaking apart of rock and the activities of living things also contributing to the formation of soil. Soil begins when bedrock, aka parent material is weathered Over time, organisms like bacteria, fungi, and insects begin living among the weathered places Organic waste from these organisms add nutrients to the weathered material, forming soil Soil is both biotic and abiotic Some living things break down (decompose) the remains of dead organisms. This forms humus, a substance that is nutrient rich that plants need to grow Larger animals, like earthworms and moles live in the soil, they loosen up and mix the soil as they burrow, increasing the air and drainage of the soil Some soils have greater organic content than others Soil horizons are typically made up of a top layer of soil that contains the most developed soil, the lower layers are made of less weathered materials Soil that developed from the bed rock below it is residual soil, the soil that has undergone erosion and deposition is called transported soil. Bedrock and soil may contain the same minerals, bed in different ratios due to chemical weathering A vertical section of soil layers from the top layer down is a soil profile Each layer of soil in a soil profile is a soil horizon Main horizons are: o, a, b, c The A horizon is the topmost layer of soil, often referred to as topsoil, it contains the most humus. The B horizon is under the A it has larger, less weathered rock fragments and less humus than the A horizon The C horizon is under the B horizon, it is the least-developed layer, containing the largest rock fragments and no organic matter Solid rock is under the C horizon Characteristics Factors that affect weathering of soil include rock type, climate, topography, and the abundance and variety of living things Soil texture described the soil based of the relative amounts of soil particles. Soil particles can be classified as sand (the largest particle), silt, or clay (the smallest particle) Soil color depends on the mineral and organic matter that make up the soil Soil pH is a measure of how acidic or basic the soil is. Soil pH is depends on the minerals, sediment, and organic matter found in the soil Pore space describes the space between the soil particles. Water and air are found in the pore space of soil Soil fertility describes how well a soil can support plant growth. Soil fertility depends of climate, the amount of humus, minerals, and nutrients, and topography of the area. |