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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 ... – PowerPoint PPT presentation

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Title: 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.

3
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.

4
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.
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