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 are dried under 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