Soil Analysis

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Soil Analysis
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What Is Soil?

• Mixture of organic and inorganic material
• May range from 100 inorganic (sand) to nearly
  100 organic (peat)
• Inorganic part is minerals
• Organic part is decayed plant and animal material
  and is sometimes called humus

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Forensic Significance of Soil

• Soil is class evidence - cannot be individualized
  to a particular location
• There is no classification system for soils
• Soils can be easily transported
• Soils within a few meters horizontally or
  vertically differ

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Forensic Geology In Intelligence Work

• Remember the outcrop you saw behind Osama bin
  Laden on TV after September 11. What was the
  location?
• A geologist who has done field work in the area
  would be able to locate that outcrop, and that
  actually happened Geologist John Shroder was
  able to identify the region where bin Laden had
  been sighted in Afghanistan in 2001 (see
  Geotimes, February 2002).

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Soil Layers
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Properties of Soil

• Soil includes the disintegrated surfaces material
  that is found on or near the Earth's surface.
• Soil can include
• Rocks
• Minerals
• Vegetation
• Animal matter
• Glass
• Paint chips
• Asphalt
• Brick

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Physical Properties of Soil

• Soil Texture, Structure, Compaction
• is the percent of sand, silt and clay in a soil.
• sand is the coarsest (0.06 - 2 mm)
• silt is intermediate (0.002 - 0.06 mm)
• clay is the finest (lt0.002 mm)

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Soil Texture

• The texture of a soil is determined by the
  percentages of particles like sand, silt, clay
  that it contains.

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Physical Properties
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Chemical Properties
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Density
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How is Soil Analyzed?

• Color comparisons of dry samples under identical
  conditions
• You want dry soil because wet soil is darker.
• Microscopic examination for debris.
• Geologically for rocks and minerals.
• Density-Gradient Tube Technique

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Soil Core Sampling
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Density-Gradient Tube

• The low density is at the top of the tube, and
  the liquid becomes more dense as you travel down
  the tube.
• Distribution patterns from several samples can be
  compared.

Sample from Crime Scene
Sports Stadium
College Gardens
Courtyard