Soil evidence

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Soil evidence
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• Dust Dirt
• This type of evidence can reveal where a person
  has been, where they live, where they work, and
  if they have pets.
• Alibi soil samples are taken in many criminal
  investigations with most soil samples taken from
  the top surface of the soil in small amounts.

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How is soil useful?

• Soil is a complex mixture of organic and
  inorganic materials.
• Great variation of these combinations leads some
  to believe that soil has a unique composition in
  any given area and changes detectably every few
  feet.

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Soil Formation

• Soil forms from the breakdown or weathering of
  parent rock.
• Parent rockan area of bedrock that is the source
  for an area of soil
• Mechanical (wind and waves) and chemical (acid
  rain) weathering help in this process as well as
  the influence of plants and animals.

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Information obtained from soils

• Texture and color
• Texture
• Soil is separated into three major texture
  categories, based upon particle size within it
  Sand, Clay, Silt.
• Use texture triangle to identify soil type

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• Color
• Grey soils water logged . . . No oxidation
• Orange/red soils influenced by iron oxides
• Dark black soils nutrient rich, lots of
  decomposed dead organic matter (humus)

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• Key
• Forensic scientists can analyze soil composition
  to place soil with particular location
• The match is often found due to noting weather
  and bedrock of an area.