1. Soil Science

2.  Used in much the same way as forensic geology  Soil represents a combination of geologic and biologic components  Classified much more scientifically than most think  Example: 70,000 different types are recognized

3.  May establish a relationship or link to the crime, the victim, or the suspect(s)  Physical properties—density, magnetism, particle size, mineralogy, petrology  Chemical properties—pH, trace elements

4.  Types of earth materials are virtually unlimited  Wide distribution and can change over short distances  Statistical probability of a given sample having properties the same as another is very small  Evidence value of soil can be excellent

5.  Defined as a combination of mineral and organic matter along with water and air that supports life  Covers most of the ground worldwide  Largely the result of:  Weathering – decomposition or disintegration  Erosion – transport of material by wind/water

6.  Parent material  Topography of an area  Length of time it takes for soil to form  Climate  Plants and animals

7.  Parent material  The source of the weather material that produced the soil  Humus  Decayed plant/animal  Referred to as topsoil  Subsoil  Deeper soil layers  Minimal organic material

8.  Soil can be classified by grain sizes  Gravel: >2.0 mm  Sand: 2.0-.05 mm  Silt: between 0.002 and 0.05 mm  Clay: <.002 mm

9.  Accomplished by placing sample through a series of sieves  Percentages of each soil particle size are tallied and triangulated on a chart

11.  Almost always done by visual comparisons  Color and texture are the most important properties  Must be examined dry, wetness can change color  There are approx. 1,100 different soil colors  Requires use of microscopes  Dissecting microscopes are the most useful

12.  Reds/yellows are created by iron content in the soil  Dark brown/black are created by high amounts of organic material  Usually based on the Munsell color chart  The basis for most computer graphics models

13.  RGB Values  Based on amounts of Red, Green and Blue hues  Require specific computerized devices for accurate measurements  “eyeball” measurements can also be made since human eye is very sensitive to color  Usually expressed in 3 values from 0-255

14. An RGB color wheel. For example, Pure White would be indicated as R=255, G=255, B=255. Pure black would be R=0, G=0, B=0. The color in the box below could be reproduced on a computer with R=73, G=0, B=238

15.  Hue  Based on five main values  Red, Yellow, Green, Blue, Purple  Value  A factor of lightness  “10” = White, “0” = Black  Chroma  “Purity” of color

17. Use of a Munsell chart during a forensic geology investigation.