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4.4 Notes

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  1. 4.4 Notes Characteristics of Soil Pg. 111-115

  2. Soil • any disintegrated surface material, both natural and artificial, that lies on or near the earth’s surface. • Naturally occurring rocks, minerals, vegetation, animal matter • Manufactured objects

  3. Critical as evidence • prevalence at a crime scene • transferability between the scene and the criminal

  4. Soils differentiated by: • gross appearance • color (dried), texture • plant and animal materials • artificial debris • minerals and rocks present

  5. Mineral • naturally occurring crystal, approx. 2200 but only 40 are most common • Rocks are characterized by mineral content and grain size

  6. Gradient Tube Technique • Used to compare soil specimens • This test is useful when used in combination of other tests • Fill a tube with liquids of different densities • Layer on bottom is most dense, each subsequent layer is of decreasing density • Add soil samples • Particles of same density will be suspended in the match point density

  7. Collection and Preservation • Standard/reference soils collected at various intervals within 100 yd radius • Samples collected at the alibi locations • Need 1-2 T of soil for a sample • Specimens packaged in individual containers • Objects with soil are collected • Samples of soil are collected under car fenders and frame • need to keep in lump form

  8. In-Class Assignment/Homework