Characteristics of Soil Pg. 111-115 4.4 Notes Characteristics of Soil Pg. 111-115

Objectives List the important forensics properties of soil Describe proper collection of soil evidence

Soil any disintegrated surface material, both natural and artificial, that lies on or near the earth’s surface. Naturally occurring rocks, minerals, vegetation, animal matter Manufactured objects

prevalence at a crime scene Critical as evidence prevalence at a crime scene transferability between the scene and the criminal

Soils differentiated by: gross appearance color (dried), texture plant and animal materials artificial debris minerals and rocks present

naturally occurring crystal, approx. 2200 but only 40 are most common Mineral naturally occurring crystal, approx. 2200 but only 40 are most common Rocks are characterized by mineral content and grain size

Density Gradient Tube Technique Used to compare soil specimens This test is useful when used in combination of other tests Fill a tube with liquids of different densities Layer on bottom is most dense, each subsequent layer is of decreasing density Add soil samples Particles of same density will be suspended in the match point density

Collection and Preservation Standard/reference soils collected at various intervals within 100 yd radius Samples collected at the alibi locations Need 1-2 T of soil for a sample Specimens packaged in individual containers Objects with soil are collected Samples of soil are collected under car fenders and frame need to keep in lump form

In-Class Assignment/Homework