1. Soil Analysis

2. What Is Soil? Mixture of organic and inorganic material
May range from 100% inorganic (sand) to nearly 100% organic (peat)
Inorganic part is minerals
Organic part is decayed plant and animal material and is sometimes called humus

3. Forensic Significance of Soil
Soil is class evidence - cannot be individualized to a particular location
There is no classification system for soils
Soils can be easily transported
Soils within a few meters horizontally or vertically differ

4. Forensic Geology In Intelligence Work
Remember the outcrop you saw behind Osama bin Laden on TV after September 11. What was the location?
A geologist who has done field work in the area would be able to locate that outcrop, and that actually happened: Geologist John Shroder was able to identify the region where bin Laden had been sighted in Afghanistan in 2001 (see Geotimes, February 2002).

5. Soil Layers

6. Properties of Soil
Soil includes the disintegrated surfaces material that is found on or near the Earth's surface.
Soil can include:
Rocks
Minerals
Vegetation
Animal matter
Glass
Paint chips
Asphalt
Brick

7. Physical Properties of Soil
Soil Texture, Structure, Compaction
is the percent of sand, silt and clay in a soil.
sand is the coarsest ( mm)
silt is intermediate ( mm)
clay is the finest (<0.002 mm)

8. Soil Texture
The texture of a soil is determined by the percentages of particles like sand, silt, & clay that it contains.

9. Physical Properties

10. Chemical Properties

11. Density

12. How is Soil Analyzed?
Color comparisons of dry samples under identical conditions
You want dry soil because wet soil is darker.
Microscopic examination for debris.
Geologically for rocks and minerals.
Density-Gradient Tube Technique

13. Soil Core Sampling

14. Density-Gradient Tube:
The low density is at the top of the tube, and the liquid becomes more dense as you travel down the tube.
Distribution patterns from several samples can be compared.
Sample from
Crime Scene
College
Gardens
Sports
Stadium
Courtyard