Trace Evidence (Soil)

DaiJah, Tia, Summer, Rihanean

Physical Properties?

Features of the soil profile and the soil horizons are often described in the field in terms of the soil's physical properties. Horizons are defined based on difference in the physical properties.

  • Soil Texture
  • Soil Structure
  • Soil Consistence/Soil Strength
  • Soil Color
  • Soil Permeability
  • Soil Temperature

Chemical Properties?

  1. pH
  2. Salinity (EC)
  3. Cation exchange capacity (CEC)
  4. Organic matter
  5. C:N ratio (Carbon to Nitrogen)
  6. Soil pH is probably the most commonly measured soil chemical property and is also one of the more informative. Like the temperature of the human body, soil pH implies certain characteristics that might be associated with a soil. Since pH (the negative log of the hydrogen ion activity in solution) is an inverse, or negative, function, soil pH decreases as hydrogen ion, or acidity, increases in soil solution. Soil pH increases as acidity decreases.
  7. Soils are composed of solid, liquid, and gas; soluble and insoluble; and organic as well as inorganic substances. There are ions and compounds, salts, acids, bases, minerals, and rock fragments. There are also colloids which are very active chemically. They are very fine soil particles, including humus, fine silicate clays, and oxides and hydroxides of iron and aluminum. Colloids carry electrochemical charges, both positive and negative, and these charges develop by substitution in the lattice structure and dissociation of active groups.

Test, Labs, and Analyzing

Soil is important evidence because it's everywhere and easily transferred. Scientist compare soil samples to establish a link or relationship. The more characteristics that can be matched the greater The probability of common origin.

Soil is most common in the world. It's mixed with different-sized mineral grains. The proportions of sand, silt, clay and organic matter determine a soils properties. Pg272

Soils composition is different from place to place and is controlled by factors; climate, parent material, living organisms, topography and time. A sample taken a few meters deep is different from a sample up above.

Case Study

In 2000, an Australian mother an son had gone missing. The main suspect was Moonta. Her car had been found next to a muddy are with a shovel covers in mod and done blood on it. The investigators insisted that the area was to large to be searched all at once, so they began to look I to the soil on the shovel. The way the soil was on the shovel,roved that it had been in a moist area, the way the soil was stuck to the back of the shovel showed it had been used to try and flatten something. The brains found in this particular soil was only found in that one area where the car was found, and was found only at a certain height if ground, yellowish pink material had the appearance of mixture with iron Oxus and clay. They used the geographical map that showed were that soul could be found at, and when they went to search that area, it had been what they'd expected. It was in a wet area, in not to far was a hand gourd stick half way out of the ground and the two bodies had do then been discovered.
Crime Scene Investigation: "Examination of Soil, Hair, Footprints..." 1969 FBI Training Film 9min