Urban Soils - Forensic Opportunities.

Geoscience techniques used in the analysis of evidence derived from the Earth have involved soil, sand and rock dust. Such materials are common in rural locations and restricted to parks, recreational areas, gardens and waste ground in urban areas. This work outlines why and how these techniques are applicable to the whole urban environment, the main differences being the types and amounts of materials analysed and the techniques utilised. The range of geoscience applications can be summarised as those deployed at the broad (kilometres, decimeters) to small (decimeters to millimeter) scale. The broad spatial variation in soil, roadway, water, buildings materials and wind- or water-borne particles can be contrasted with the variation in urban materials from dwelling to streets or gardens and parks, along with the micro-spatial and stratigraphic variation in each. In addition, geoscience principles and techniques that have not been used before can be applied to urban materials to provide comparisons of material that were not previously achievable, or to add a further proxy to established methods. The latter point is demonstrated with a case study using x-ray diffraction and QemScan, of a criminal case where building plaster with peculiar qualities could be compared from a suspectÕs vehicle to the escape route from a murder scene.