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Soil Analysis

Soil Analysis. Forensic Characteristics of Soil. Soil includes any disintegrated surface material, that lies on or near the earth’s surface Value based on prevalence at crime scenes and ability to transfer between scene and criminal

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Soil Analysis

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  1. Soil Analysis

  2. Forensic Characteristics of Soil • Soil includes any disintegrated surface material, that lies on or near the earth’s surface • Value based on prevalence at crime scenes and ability to transfer between scene and criminal • Most soils can be differentiated and distinguished by appearance (visual comparison)

  3. What Is Soil? Mixture of organic and inorganic material • Inorganic part contains minerals • Organic part is decayed plant and animal material • Three textures of soil (based on particle size) • Clay (fine) – retains water • Silt (medium/gritty) – may retain some water • Sand (coarse/granular) – air circulates, loses water

  4. Soil Analysis • Soil is darker when wet. Color comparisons must always be made when all the samples aredriedunder identical laboratory conditions. • There are an estimated 1,100 • distinguishable soil colors. • There are at least 50,000 different soil types in the United States alone. • Low-power microscopic examination reveals the presence of plant and animal materials as well as artificial debris.

  5. Soil Analysis • Bulk analysis • Density gradient • Particle size distribution (sieve) • Color • Mineral analysis • pH • Oxygen levels • Organic components

  6. Soil comparison: Density Gradient tube used to compare soil samples 1.0 g/ml 1.5 g/ml

  7. Finding gravesites • Altered soil profiles can indicate land was disturbed • Discoloration • Excess soil may be mounded above a new grave • Older gravesites tend to sink as loose soil is compacted and body decomposes • More easily detected from above due to shadowing • Acidic areas reduce decomposition due to fewer microorganisms (more preserved) • Coarse/sandy soils cause bodies to mummify

  8. SOIL

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