Forensic geology

Forensic geology is the study of evidence relating to materials found in the Earth used to answer questions raised by the legal system.

In 1975, Ray Murray and fellow Rutgers University professor John Tedrow published Forensic Geology.

The main use of forensic geology as it is applied today is regarding trace evidence. By examining the soil and sediment particles forensic geologists can potentially link a suspect to a particular crime or a particular crime scene.

Forensic geologists work with many other disciplines of science such as medicine, biology, geography, and engineering amongst others.

In 2008, Alastair Ruffell and Jennifer McKinley, both of Queen's University Belfast, published Geoforensics a book that focuses more on the use of geomorphology and geophysics for searches. In 2010, forensic soil scientist Lorna Dawson of the James Hutton Institute co-edited and contributed chapters to the textbook Criminal and Environmental Soil Forensics. In 2012, Elisa Bergslien, at SUNY Buffalo State, published a general textbook on the topic, An Introduction to Forensic Geoscience.

According to Murray, forensic geology began with Sherlock Holmes writer, Sir Arthur Conan Doyle. The character Sherlock Holmes claimed to be able to identify where an individual had been by various methods, including his having memorized the exposed geology of London to such a degree that detecting certain clays on a person's shoe would give away a locale. Georg Popp, of Frankfurt, Germany, may have been the first to use soil analysis for linking suspects to a crime scene. In 1891, Hans Gross used microscopic analysis of soils and other materials from a suspect's shoes to link him to the crime scene.

Colour is one of the most important physical characteristics associated with soil samples. One technique used is comparing the soil to the Munsell soil chart. In a majority parts of the world during a forensic investigation determining the soil colour is required. This analysis can be achieved in the field itself with the Munsell soil chart using human perspective. Although colour is a very subjective topic, two people can have a complete different perception of colour and could then associate it differently with the Munsell soil chart thus effecting the accuracy of this method.

.To avoid the errors of simply using human perception, to obtain objective results computer controlled spectrophotometry can be used. One computerized method is using CIELAB which consists of using an electronic spectrophotometer and calorimeter to create 3D plotting of colour. Using three coordinates L* relates to a reflection of lightness, a* refers to red/ green colours and b* yellow/ blue colours. This method uses a derivative mathematical system to achieve a uniform colour space for analysis. This technique provides numerical values to be associated with colour to then be using with accordance of the Munsell soil chart.